JP3061511B2 - Photovoltaic element, method of manufacturing the same, and power generation system using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photovoltaic element comprising a laminated structure of a pin structure made of a silicon-based non-single-crystal semiconductor material and a pn structure of microcrystalline silicon, polycrystalline silicon, or single-crystal silicon. The present invention relates to a manufacturing method thereof and a power generation system using the same.

In particular, the present invention relates to a pin-type photovoltaic element in which the band gap in an i-type layer changes. Further, the present invention relates to a method for depositing the photovoltaic element by a microwave plasma CVD method. In addition, the present invention relates to a power generation system using the photovoltaic element.

[0003]

2. Description of the Related Art Conventionally, in a photovoltaic device having a pin structure made of a silicon-based non-single-crystal semiconductor material, an i-layer contains silicon atoms and germanium atoms or carbon atoms,
Various proposals have been made for photovoltaic elements in which the band gap is changed. For example, (1) “Optimum deposition conditions for a- (Si, G
e): H using a triode-configurated rf glow discharge
system ”, JA Bragagnolo, P. Littlefield, A. Mastro
vito and G. Storti, Conf. Rec. 19th IEEE Photovolta
ic Specialists Conference-1987, pp.878, (2) “Efficiency improvement in amorphous-SiGe: H
solar cells and its application to tandem type so
lar cells ”, S. Yoshida, S. Yamanaka, M. Konagai and
K.Takahashi, Conf.Rec.19th IEEE Photovoltaic Spec
ialists Conference-1987, pp.1101, (3) “Stability and terrestrial application of a
-Si tandem type solarcells ”, A.Hiroe, H.yamagish
i, H. Nishio, M. Kondo, and Y. Tawada, Conf. Rec. 19t
h IEEE Photovoltaic Specialists Conference-1987, p
p.1111, (4) “Preparation of high quality a-SiGe: H films
and its application to the high efficiency triple
-junction amorphous solar cells, ”K.Sato, K.Kawaba
ta, S. Terazono, H. Sasaki, M. Deguchi, T. Itagaki, H.
Morikawa, M.Aigaand K.Fujikawa, Conf.Rec. 20th IE
EE Photovoltaic Specialists Conference-1988 pp.7
3, (5) USP 4,816,082, etc. have been reported.

A theoretical study of the characteristics of a photovoltaic device in which the band gap is changed is described in, for example, (6) “A novel design for amorphous silicon alloy”.
solar cells ”, S. Guha, J. Yang, A. Pawlikiewicz, T.
Glatfelter, R. Ross, and SR0vshinsky, Conf. Rec. 2
0th IEEE Photovoltaic Specialists Conference-1988
pp.79, (7) “Numerical mode1ing of multijunction, amorph
ous silicon based PIN solar cells ”, AHPawliki
ewicz and S. Guha, Conf. Rec. 20th IEEE Photovoltai
c Specialists Conference-1988 pp.251, etc. have been reported.

In such a conventional photovoltaic device, p
A layer having a changed band gap is inserted at the interface for the purpose of preventing recombination of photoexcited carriers near the / i, n / i interface, increasing the open-circuit voltage, and improving the hole carrier range. doing.

Further, p formed on a polycrystalline silicon substrate
A photovoltaic device in which an n junction and a pin junction made of amorphous silicon are stacked has been reported. For example, (8) “Amorphous Si / polycrystalline Si Stacked So
lar Cell Having More Than 12% Conversion Efficienc
y ”, Koji Okuda, Hiroaki Okamoto and Yoshihiro Ham
akawa, Japanese Journal of Physics, Vol.22 No.9 Se
p. 1983 pp. L605, (9) “Device Physics and optimum Design of a-Si /
poly Si Tandem Solar Cells ”, H. Takakura, K. Miyag
i, H.Okamoto, Y.Hamakawa, Proceedings of 4thIntern
atinal Photovoltaic Science and Engineering Confer
ence l989 pp.403.

[0007] A photovoltaic element has been reported in which a doping layer is formed by laminating a layer mainly composed of a Group III element of the periodic table and a layer mainly composed of silicon and carbon. For example, (10) “Characterization of δ-doped a-SiC p-Lay
er Prepared by Trimethylboronand Triethylboron and
Its Application to Solar Cells ”, K.Higuchi, K.Ta
buchi, S. Yamanaka, M. Konagai and K. Takahashi, Proc
eedings of 5th Intenatinal Photovoltaic Science an
d Engineering Conference l990 pp.529, (11) “High Efficiency amorphous Silicon Solar
Cells with "Delta-Doped" P-Layer ", Y. Kazama, K. Sek
i, WYKim, S. Yamanaka, M. Konagai and K. Takahashi,
Japanese Journal of Applied Physics vol.28 No.7 J
uly l989 pp.1160-1164, (12) “High Efficiency Delta-Doped Amorphous Si
licon Solar Cells Prepared by Photochemical Vapor
Deposition ”, K. Higuchi, K. Tabuchi, KSLim, M. Kona
gai and K. Takahashi, Japanese Journal of Applied P
hysics Vol.30 No.8 August l991 pp.1635-l640, (l3) “High Efficiency Amorphous Silicon Solar
Cells with “Delta-Doped“ P-Layer ”, A. Shibata, YK
azama.K.Seki, WYKim, S.Yamanaka, M.Konagai and
K. Takahashi, Conf. Rec. 20th IEEE Photovo1taic Spe
cialists Conference-l988 pp.317, etc.

[0008]

The conventional photovoltaic device containing silicon atoms and carbon atoms and having a changed band gap is practically a recombination of photoexcited carriers, an open voltage, and a carrier range of holes. Further improvement is desired for. In addition, long wavelength sensitivity of 800 nm or more is poor, and further improvement is desired.

Further, such a photovoltaic element has a problem that the conversion efficiency is reduced when the photovoltaic element is irradiated with light. There is also a problem that if the i-layer of the photovoltaic element has a strain and is annealed where there is vibration or the like, the photoelectric conversion efficiency decreases.

On the other hand, the conventional pin / pn stacked type photovoltaic element has a problem that the open-circuit voltage is small, a problem that the conversion efficiency is reduced when light is irradiated on the photovoltaic element, There is a problem that the photoelectric conversion efficiency is reduced when annealing is performed in a place where the i-layer has distortion and vibrations or the like.

An object of the present invention is to provide a photovoltaic element which solves the above-mentioned conventional problems. That is, an object of the present invention is to provide a photovoltaic element in which recombination of photoexcited carriers is prevented, and an open voltage and a carrier range of holes are improved.

Another object of the present invention is to provide a photovoltaic element in which conversion efficiency is unlikely to be reduced when light is irradiated to the photovoltaic element.

It is a further object of the present invention to provide a photovoltaic element in which the photoelectric conversion efficiency is unlikely to decrease when annealing is performed under vibration for a long period of time.

It is a further object of the present invention to provide a photovoltaic device having improved short-wavelength sensitivity and long-wavelength sensitivity and an improved short-circuit current.

Still another object of the present invention is to provide a method of manufacturing a photovoltaic device which has achieved the above-mentioned object.

Still another object of the present invention is to provide a power generation system using a photovoltaic element that achieves the above object.

[0017]

Means for Solving the Problems The photovoltaic element of the present invention which has been found to solve the above-mentioned problems is provided on an n (p) type substrate made of polycrystalline silicon or single crystal silicon. A first p (n) -type layer made of microcrystalline silicon, polycrystalline silicon, or single-crystal silicon, an n (p) -type layer made of a non-single-crystal semiconductor material, an i-type layer made of a non-single-crystal semiconductor material, And a second p (n) -type layer made of a non-single-crystal semiconductor material, the i-type layer contains at least silicon atoms and carbon atoms, and extends in the layer thickness direction. the band gap is changed smoothly, when the minimum band gap was positioned second p-type layer than the position of the center of the thickness (p-type layer) are offset to the side together
The valence electron controlling agent serving as a donor and the
A valence electron controlling agent serving as a putter is doped together .

In a preferred embodiment of the photovoltaic device of the present invention, at least one of the p / i interface and the n / i interface of the i-type layer has a maximum value of the band gap of the i-type layer. The range of the band gap maximum value is 1 to 3
It is a photovoltaic element within 0 nm.

[0019] In the photovoltaic device of the present invention, the valence control agent comprising the valence control agent and an acceptor which serves as a donor in the i-type layer are contained at the same time. Preferably, the valence electron controlling agent serving as the acceptor is a group III element of the periodic table, and the valence electron controlling agent serving as a donor is a group V element and / or a group III element of the periodic table. More preferably, the electronic control agent is distributed in the i-type layer.

A preferred embodiment of the photovoltaic device of the present invention is a photovoltaic device in which the i-type layer contains oxygen atoms or nitrogen atoms.

In addition, a desirable mode of the photovoltaic device of the present invention is a photovoltaic device in which the hydrogen content contained in the i-type layer changes in accordance with the content of silicon atoms.

In addition, a desirable mode of the photovoltaic device of the present invention is such that the first p (n) type layer, the n
At least one of the (p) -type layer and the second p (n) -type layer is composed of silicon and at least one element whose main constituent element is selected from carbon, oxygen and nitrogen;
A layer containing a Group III element, a Group V element, or a Group VI element of the periodic table as a valence electron controlling agent;
A photovoltaic element characterized by having a layered structure including a layer mainly containing a Group 5 element, a Group V element, or a Group VI element.

The power generation system according to the present invention comprises the photovoltaic element according to the present invention, and a voltage and / or current of the photovoltaic element, and monitors the power from the photovoltaic element to a storage battery and / or an external load. A control system for controlling the supply of
And a storage battery for storing power from the photovoltaic element and / or supplying power to an external load.

In the method of manufacturing a photovoltaic device according to the present invention, the microwave energy lower than the microwave energy required to decompose the raw material gas for depositing a deposited film by 100% at an internal pressure of 50 mTorr or less is applied to the i-type layer. Is applied to the source gas, and at the same time, RF energy higher than the microwave energy is applied to the source gas.

[0025]

The present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic explanatory view of a photovoltaic element of the present invention. In FIG. 1, a photovoltaic element of the present invention comprises a back electrode 101, an n (p) type silicon substrate 102, a first p
(N) -type layer 103, n (p) -type layer 104, substantially i-type non-single-crystal semiconductor layer containing silicon atoms and carbon atoms (hereinafter referred to as i-type layer) 105, and second p-type layer It comprises an (n) type layer 106, a transparent electrode 107, a current collecting electrode 108, and the like.

FIGS. 2-1 to 3-7 are schematic illustrations of examples of changes in the band gap of the photovoltaic device of the present invention. This figure shows that half of the band gap (Eg /
The change of the band gap in the i-type layer is shown based on 2). In the figure, the left side is the n / i interface side, and the right side is p / i.
On the interface side.

In the present invention, since the position of the minimum band gap of the i-type layer is offset toward the p / i interface side, the electric field of the conduction band is large on the p / i interface side of the i-type layer. Holes can be efficiently separated, and recombination of electrons and holes can be reduced. Also, in the i-type layer, n / i
Since the electric field in the valence band increases toward the interface, recombination between electrons and holes that are photoexcited near the n / i interface can be reduced.

Further, by adding both a valence electron controlling agent as a donor and a valence electron controlling agent as an acceptor to the i-type layer, the carrier range of electrons and holes can be extended. In particular, by including a relatively large amount of the valence electron controlling agent at the maximum band gap, the carrier range of electrons and holes can be effectively extended. As a result, a high electric field near the p / i interface and n /
The high electric field in the vicinity of the i-interface can be used more effectively, and the collection efficiency of electrons and holes photo-excited in the i-type layer can be remarkably improved. Moreover, near the p / i interface and n /
By compensating the defect levels (so-called D ^- and D ⁺ ) in the vicinity of the i interface with the valence electron controlling agent, dark current (during reverse bias) due to hopping conduction via the defect levels is reduced. In particular, in the vicinity of the interface, the internal stress such as strain due to a sudden change of a constituent element peculiar to the interface can be reduced by containing a valence electron controlling agent more than the inside of the i-type layer. And the defect level near the interface can be reduced. As a result, the open-circuit voltage and the fill factor of the photovoltaic element can be improved.

In addition, by including both a valence electron controlling agent serving as a donor and a valence electron controlling agent serving as an acceptor in the i-type layer, the durability against light degradation is increased. Although the details of the mechanism are unknown, it is generally considered that the dangling bonds generated by light irradiation become recombination centers of carriers and deteriorate the characteristics of the photovoltaic element.
In the case of the present invention, both the valence electron controlling agent serving as a donor and the valence electron controlling agent serving as an acceptor are contained in the i-type layer, and they are not 100% activated. As a result, even if dangling bonds are generated by light irradiation, it is considered that they react with the inactive valence electron controlling agent to compensate for dangling bonds.

In addition, even when the light intensity applied to the photovoltaic element is low, the probability of trapping photoexcited electrons and holes is reduced because the defect level is compensated by the valence electron controlling agent. . Further, as described above, since the dark current at the time of reverse bias is small, a sufficient electromotive force can be generated. As a result, excellent photoelectric conversion efficiency is exhibited even when the light intensity applied to the optical storage element is low.

In addition, the photovoltaic device of the present invention is one in which the photoelectric conversion efficiency does not easily decrease even when annealing is performed under vibration for a long period of time. Although the detailed mechanism is unknown, the photovoltaic element is formed by changing the constituent elements in order to continuously change the band gap. Therefore, strain is accumulated inside the photovoltaic element. That is, many weak couplings exist inside the photovoltaic element. Then, the weak bond in the i-type layer is broken by vibration, and an unbonded bond is formed. However, in the present invention, by adding both a valence electron controlling agent serving as a donor and a valence electron controlling agent serving as an acceptor, local flexibility is increased, and the photovoltaic element can be used even in annealing by long-term vibration. It is considered that the decrease in the photoelectric conversion efficiency of can be suppressed.

In the photovoltaic element according to the present invention, the p-type semiconductor layer is formed of a microcrystalline, polycrystalline or single-crystal silicon semiconductor layer.
By laminating a pin structure composed of an i-type layer or the like having silicon atoms and carbon atoms as main constituent atoms on the n structure, the sensitivity to short-wavelength light and long-wavelength light is particularly improved, The current is improved, and the open-circuit voltage is further improved.

Further, the n (p) -type layer formed of a non-single-crystal material on the pn junction is easily formed because the underlying layer is made of a microcrystalline, polycrystalline or single-crystal silicon semiconductor material. Since microcrystallization or polycrystallization can be performed, open-circuit voltage or short-circuit photocurrent can be improved.

Further, by stacking an i-type having silicon atoms and carbon atoms as main constituent atoms on an n (p) type layer made of microcrystalline silicon or polycrystalline silicon semiconductor layer material, The denseness of the i-type layer is improved, and a decrease in photoelectric conversion efficiency (light deterioration) particularly when light is irradiated for a long period of time can be reduced. Can be suppressed.

Further, before laminating a pin structure composed of an i-type layer or the like having silicon atoms and carbon atoms as main constituent atoms on the pn junction, hydrogen plasma treatment is carried out, so that hydrogen atoms are generated in defects at crystal grain boundaries. The i-type layer containing silicon atoms and carbon atoms as main constituent elements can be formed on the pn junction by compensating for defects by defects and relaxing atoms in the vicinity of crystal grain boundaries to reduce defect levels. This improves the photoelectric conversion efficiency of the photovoltaic element in the case where a pin structure made of the above is laminated. In addition, the contact surface of the metal electrode of the pn laminated structure and the contact surface of the pin structure can provide more current and electromotive force by providing a degenerated semiconductor layer.

Further, in the photovoltaic device of the present invention, since the i-type layer is formed by the microwave plasma CVD method of the present invention, hydrogen atoms are bonded to defects at the crystal grain boundaries of the substrate by more active hydrogen radicals. Defects can be compensated and atoms in the vicinity of crystal grain boundaries can be relaxed to reduce defect levels, thereby improving the photoelectric conversion efficiency of the photovoltaic element.

In the example of FIG. 2A, the position of the minimum band gap is located near the p / i interface, and the maximum value of the band gap is in contact with the p / i interface and the n / i interface. Is what it is. In FIG. 2-2, as in FIG. 2A, the minimum value of the band gap is located near the p / i interface, but the maximum value of the band gap is located in contact with the p / i interface. Things. In particular, the open-circuit voltage can be increased by adopting the band gap configuration shown in FIG.

FIGS. 3-1 to 3-7 show changes in the band gap of a photovoltaic device having a band gap constant region in the i-type layer near the p / i interface or / and near the n / i interface. FIG. Each figure depicts a change in band gap based on Eg / 2. The left side of the band diagram is the n / i interface, and the right side is the p / i interface. FIG.
-1 indicates that there is a constant band gap region 312 in the i-type layer near the second p / i interface, and the band gap is n / i.
Region 31 decreasing from interface side toward p / i interface
1 is an example. The minimum value of the band gap is at the interface between the region 312 and the region 311. In addition, the bonding of the bands between the region 311 and the region 312 is such that the bands are discontinuously connected. By providing such a region having a constant band gap, dark current due to hopping conduction via a defect level at the time of reverse bias of the photovoltaic element can be suppressed as much as possible. As a result, the open-circuit voltage of the photovoltaic element increases. The layer thickness of the region 312 having a constant band gap is a very important factor, and the preferable range of the layer thickness is 1 to 30 nm.
It is. If the layer thickness in the region where the band gap is constant is smaller than 1 nm, the dark current due to hopping conduction via the defect level cannot be suppressed, and the improvement of the open-circuit voltage of the photovoltaic element cannot be expected. On the other hand, when the layer thickness of the region having a constant band gap is larger than 30 nm, holes excited by light are likely to be accumulated near the interface between the region 312 having a constant band gap and the region 311 having a changing band gap. The collection efficiency of photoexcited carriers is reduced. That is, the short-circuit photocurrent is reduced.

FIG. 3B shows a region 322 having a constant band gap near the p / i interface of the i-type layer, and a band gap 322 near the n / i interface of the region 321 where the band gap changes. Here is an example that is equal to

FIG. 3C shows regions 332, 3 having a constant band gap in the i-type layer near the p / i interface and near the n / i interface.
33 is provided. Near the p / i interface and n / i
By providing a constant band gap region in the i-type layer near the interface, when a reverse bias is applied to the photovoltaic element, the dark current is further reduced and the open voltage of the photovoltaic element is increased. .

FIGS. 3-4 to 3-7 show that the i-type layer near the p / i interface or / and the n / i interface has a region with a constant band gap, and the p / i interface or n / i interface. It is an example of the photovoltaic device of the present invention having a region where the band gap changes rapidly in the direction of the i interface.

FIGS. 3-4 show the vicinity of the p / i interface and n / i
A constant band gap region 342 in the i-type layer near the interface;
There is a region 341 having a band gap changing, and the region 341 has a band gap minimum position offset toward the p / i interface side, and the band gap of the region 341 and the band gap of the regions 342 and 343 are present. This is an example where gaps are linked. By continuing the band gap, electrons and holes that are photoexcited in the region where the band gap of the i-type layer changes can be efficiently collected in the n-type layer and the p-type layer, respectively. In particular, when the band gap constant regions 342 and 343 are as thin as 5 nm or less, i
In the region where the band gap of the mold layer changes rapidly, the dark current when a reverse bias is applied to the photovoltaic element can be reduced, and thus the open voltage of the photovoltaic element can be increased. It is.

FIG. 3-5 shows that the area 351 where the band gap changes is equal to the areas 352 and 35 where the band gap is constant.
This is an example in which the connection with No. 3 is discontinuously and relatively loosely connected.
However, since they are gently connected in the direction in which the band gap expands in the band gap changing region and the band gap changing region, carriers that are photo-excited in the band gap changing region efficiently have a constant band gap. Implanted into the region. As a result, the collection efficiency of the photoexcited carriers increases.

Whether a region having a constant band gap and a region having a changing band gap are connected continuously or discontinuously is determined as a region having a constant band gap and a region having a rapidly changing band gap. Depends on the thickness of the layer. In the case where the region having a constant band gap is 5 nm or less and the thickness of the region where the band gap changes rapidly is 10 nm or less, the region having a constant band gap and the region where the band gap changes are continuously formed. The connection increases the photoelectric conversion efficiency of the photovoltaic element. On the other hand, when the layer thickness of the region where the band gap is constant is more than 5 nm and the layer thickness of the region where the band gap changes rapidly is 10 to 30 nm, the band gap changes with the region where the band gap is constant. The conversion efficiency of the photovoltaic element is improved when the area is discontinuously connected.

FIG. 3-6 shows an example in which a region where the band gap is constant and a region where the band gap changes are connected in two stages. In this example, the position where the band gap is minimum is near the p / i interface. Carriers photo-excited in a region 361 where the band gap is changed by connecting to a fixed region 362 having a wide band gap through a step of gradually expanding the band gap from a position where the band gap is extremely small and a stage of rapidly expanding the band gap. Can be collected efficiently. Also, in FIG.
The i-type layer near the i-interface has a region where the band gap changes rapidly toward the n / i-interface.

FIGS. 3-7 show the vicinity of the p / i interface and n / i
Both i-type layers near the interface have a constant band gap region, and are connected to a constant band gap region 372 near the p / i interface from the band gap change region 371 through a two-step band gap change. , N / i interface is connected to a region 373 having a constant band gap by a sudden change in the band gap.

As described above, the internal strain can be reduced by connecting the band gap constant region and the band gap changing region in a similar state of the constituent elements. As a result, even if annealing is performed for a long period of time under vibration, the phenomenon that a weak bond in the i-layer is cut and the defect level increases, and the photoelectric conversion efficiency decreases, is unlikely to occur.
High photoelectric conversion efficiency can be maintained.

Further, by incorporating the valence electron controlling agent into the i-type layer, the carrier range of the carriers in the i-type layer can be increased, so that the carrier collection efficiency can be increased. In particular, the collection efficiency of photoexcited carriers can be further increased by reducing the number of valence electron controlling agents in a narrow band gap and increasing the number in a wide band gap corresponding to the change of the band gap. Further, the p / i layer is contained more in the p-type layer and the n-type layer in the region where the band gap is constant than in the region where the band gap is minimum, so that p / i
The present invention can prevent recombination of photoexcited carriers near the interface and the n / i interface, and can improve the photoelectric conversion efficiency of the photovoltaic device.

In the present invention, the preferable range of the minimum value of the band gap of the i-type layer containing silicon atoms and carbon atoms is variously selected depending on the spectrum of irradiation light, but is 1.7 to 2.0 eV. Is desirable.

In the photovoltaic device having a continuously changing band gap according to the present invention, the inclination of the tail state of the valence band is an important factor affecting the characteristics of the photovoltaic device. It is preferable that the slope of the tail state at the minimum value of the band gap and the slope of the tail state at the maximum value of the band gap continue smoothly.

The photovoltaic element having the pin / pn structure has been described above.
The present invention can be applied to a photovoltaic element in which a pin structure such as an inpin / pn structure is stacked.

FIG. 4 is a schematic explanatory view showing an example of a manufacturing apparatus suitable for forming a deposited film of a photovoltaic element of the present invention. The manufacturing apparatus includes a deposition chamber 401, a vacuum gauge 402,
F power supply 403, substrate 404, heater 405, conductance valve 407, auxiliary valve 408, leak valve 409, RF electrode 410, gas inlet tube 411, microwave waveguide 412, dielectric window 413, shutter 41
5, source gas supply apparatus 2000, mass flow controllers 2011 to 2017, valves 2001 to 2007,
2021 to 2027, pressure regulators 2031 to 2037,
It is composed of raw material gas cylinders 2041 to 2048 and the like.

Although the details of the deposition mechanism of the microwave plasma CVD method in the deposition method of the present invention are unknown,
It can be considered as follows.

By applying microwave energy lower than the microwave energy required for decomposing the source gas to 100% to the source gas and simultaneously applying RF energy higher than the microwave energy to the source gas, the deposited film is formed. It is believed that active species suitable for formation can be selected. Further, it is considered that when the internal pressure in the deposition chamber when the source gas is decomposed is 50 mTorr or less, the mean free path of active species suitable for forming a high-quality deposited film is sufficiently long, so that the gas phase reaction is suppressed as much as possible. .

Further, the internal pressure in the deposition chamber is 50 mTorr.
It is considered that the RF energy hardly affects the decomposition of the source gas in the state of r or less, and controls the potential between the plasma in the deposition chamber and the substrate. That is, in the case of the microwave plasma CVD method, although the potential difference between the plasma and the substrate is small, the potential difference between the plasma and the substrate (+ on the plasma side and − on the substrate side) is reduced by simultaneously inputting the RF energy and the microwave energy. Can be bigger. Since the plasma potential is positive and high with respect to the substrate, active species decomposed by the microwave energy are deposited on the substrate, and at the same time, + ions accelerated by the plasma potential collide with the substrate and generate It is considered that the relaxation reaction is promoted and a high-quality deposited film is obtained. In particular, this effect becomes remarkable when the deposition rate is several nm / sec or more. Further, since RF has a high frequency unlike DC, the difference between the plasma potential and the substrate potential is determined by the distribution of ionized ions and electrons. That is, the potential difference between the substrate and the plasma is determined by the synergistic effect between the ions and the electrons. Therefore, there is an effect that spark is less likely to occur in the deposition chamber. As a result, a stable glow discharge can be maintained for a long time of 10 hours or more.

In addition, in depositing a layer with a changed band gap, the flow rate and the flow rate ratio of the source gas change with time or spatially.
It is necessary to appropriately change the C voltage over time or spatially. However, in the method for forming a deposited film according to the present invention, the ratio of ions changes due to a temporal or spatial change in the flow rate and the flow rate ratio of the source gas. The RF self-bias automatically changes accordingly. As a result, RF
When the source gas flow rate and the source gas flow rate ratio are changed by applying to the electrode, the discharge is much more stable than in the case of DC bias.

In addition, in the method of forming a deposited film according to the present invention, in order to obtain a change in band gap in the i-type layer,
It is effective to temporally change the flow rate ratio between the silicon atom-containing gas and the carbon-containing gas during the formation of the layer. At this time, it is preferable to mix the above gas at a distance of 5 m or less from the deposition chamber. Things. If the source gases are mixed at a distance of more than 5 m, even if the mass flow controller is controlled in accordance with a desired band gap change, the source gas mixing positions are far apart, so that the change of the source gases may be delayed or the source gases may not be mixed. Diffusion occurs, causing a deviation from a desired band gap. That is, if the mixing positions of the source gases are too far apart, the controllability of the band gap is reduced.

Further, in order to change the hydrogen content contained in the i-type layer in the layer thickness direction, in the method of forming a deposited film of the present invention, the RF energy applied to the RF electrode should be increased where the hydrogen content is desired to be increased. Where it is desired to increase the hydrogen content and reduce the hydrogen content, the RF energy applied to the RF electrode may be reduced. Although the detailed mechanism is still unknown, increasing the RF energy applied to the RF electrode raises the plasma potential and increases more hydrogen ions in the i-type layer because they are more accelerated toward the substrate. It is considered that a hydrogen atom is contained.

Further, in the case where DC energy is applied simultaneously with RF energy, the DC voltage applied to the RF electrode may be increased by applying a large voltage with a positive polarity where the content of hydrogen atoms is desired to be increased. When it is desired to reduce the DC voltage, a DC voltage applied to the RF electrode may be applied with a small voltage having a positive polarity. Although the detailed mechanism is still unknown, increasing the DC energy applied to the RF electrode raises the plasma potential and causes more hydrogen ions in the i-type layer to be accelerated towards the substrate. It is considered that a hydrogen atom is contained.

Further, as another method for changing the hydrogen content contained in the i-type layer in the layer thickness direction, in the method of forming a deposited film of the present invention, a halogen atom (X ) Containing gas (eg, Si
_{X 4, Si 2 X 6,} SiH N X 4- N, Si 2 H N X 6-N, etc.)
And a gas containing no halogen atom (for example, Si
H ₄ , Si ₂ H ₆ , Si ₃ H ₈ , SiD ₄ , SiHD ₃ , Si
_{H 2 D 2, SiH 3 D} , there SiD ₃ H, a method of mixing a Si ₂ D ₃ H _3, etc.) to form the i-type layer.

Where the hydrogen content is desired to be reduced, the ratio (Y) of the gas containing both halogen atoms (X) and silicon atoms to the gas containing all silicon atoms is increased,
Where the hydrogen content is to be reduced, the ratio (Y) may be reduced. Although the detailed mechanism is still unknown, when the above-mentioned gas containing fluorine atoms is made to flow more in the deposition chamber, the amount of fluorine radicals excited by microwaves in the plasma increases, and the fluorine radical fluorine It is considered that the substitution reaction occurs between the atoms and the hydrogen atoms present in the i-type layer, and the hydrogen content in the i-type layer decreases.

Further, as another method for changing the hydrogen content contained in the i-type layer in the layer thickness direction, a method of forming a deposited film according to the present invention includes the steps of:
Alternatively, xenon lamps are provided, these lamps are flashed during the formation of the i-type layer, and the substrate temperature is temporarily increased. At that time, if the hydrogen content is to be reduced, the number of flashes per unit time is increased by increasing the number of flashes per unit time, and the substrate temperature is temporarily increased.If the hydrogen content is desired to be increased, the number of flashes per unit time is reduced. The substrate temperature may be temporarily lowered. It is considered that by temporarily raising the substrate temperature, the desorption reaction of hydrogen from the surface of the i-type layer is activated.

The method of forming a deposited film according to the present invention is performed as follows.

First, a substrate 404 for forming a deposited film is mounted in the deposition chamber 401 shown in FIG. 4, and the deposition chamber is sufficiently evacuated to 10 ^-4 Torr or less. A turbo molecular pump is suitable for this exhaust, but an oil diffusion pump may be used. In the case of an oil diffusion pump, gases such as H ₂ , He, Ar, Ne, Kr, and Xe are introduced into the deposition chamber when the internal pressure of the deposition chamber 401 becomes 10 ⁻⁴ Torr or less so that oil does not diffuse back into the deposition chamber. Good to do. After sufficiently exhausting the deposition chamber, gases such as H ₂ , He, Ar, Ne, Kr, and Xe are
The pressure is introduced into the deposition chamber so that the pressure in the deposition chamber is substantially the same as when the source gas for depositing a film is flowed. The optimum pressure in the deposition chamber is 0.5 to 50 mTorr. When the internal pressure in the deposition chamber becomes stable, the heater 405
Is turned on, and the substrate is heated to 100 to 500 ° C. When the substrate temperature is stabilized at a predetermined temperature, H ₂ , H
The gases such as e, Ar, Ne, Kr, and Xe are stopped, and a predetermined amount of a source gas for forming a deposited film is introduced from a gas cylinder into the deposition chamber via a mass flow controller. The supply amount of the source gas for forming the deposited film introduced into the deposition chamber is appropriately determined by the volume of the deposition chamber.

On the other hand, the internal pressure in the deposition chamber when a source gas for depositing a deposition film is introduced into the deposition chamber is a very important factor in the deposition film forming method of the present invention. In the case of the microwave plasma CVD method, 0.5 to
50 mTorr is preferred.

In the method of forming a deposited film according to the present invention, the microwave energy input into the deposition chamber for forming the deposited film is an important factor. The microwave energy is appropriately determined depending on the flow rate of the raw material gas introduced into the deposition chamber, but is smaller than the microwave energy required to decompose the raw material gas by 100%. Is 0.005 to 1 W / c
m is ^3. A preferable frequency range of the microwave energy is 0.5 to 10 GHz. Particularly, a frequency around 2.45 GHz is suitable. Further, in order to form a deposited film with reproducibility by the deposited film forming method of the present invention and to form a deposited film for several hours to several tens of hours, the stability of the frequency of microwave energy is very important. It is preferable that the fluctuation of the frequency be in the range of ± 2%. Further, the ripple of the microwave is preferably in a range of ± 2%.

Further, in the method of forming a deposited film according to the present invention, R is supplied into the deposition chamber simultaneously with the microwave energy.
The F energy is a very important factor in combination with the microwave energy, and a preferable range of the RF energy is 0.01 to 2 W / cm ³ . The preferred frequency range for RF energy is 1
１００100 MHz. In particular, 13.56 MHz is optimal. Further, the variation of the RF frequency is preferably within ± 2%, and the waveform is preferably a smooth waveform. When the RF energy is supplied, it is appropriately selected depending on the area ratio between the area of the RF electrode for supplying the RF energy and the area of the ground. In particular, the area of the RF electrode for supplying the RF energy is larger than the area of the ground. When the width is narrow, it is better to ground the self-bias (DC component) on the power supply side for supplying RF energy. Further, when the self-bias (DC component) on the power supply side for supplying RF energy is not grounded, it is preferable that the area of the RF electrode for supplying RF energy be larger than the area of the ground to which the plasma contacts.

As described above, microwave energy is introduced from the waveguide 412 into the deposition chamber via the dielectric window 413, and at the same time, RF energy is supplied from the RF power source 403 to the RF electrode 41.
0 to the deposition chamber. In such a state, the source gas is decomposed for a desired time to form a deposited film having a desired thickness on the substrate. After that, the input of the microwave energy and the RF energy was stopped, the deposition chamber was evacuated, and H ₂ , H
After sufficiently purging with a gas such as e, Ar, Ne, Kr, or Xe, the deposited non-single-crystal semiconductor film is taken out of the deposition chamber.

Further, in addition to the RF energy, the R
A DC voltage may be applied to the F electrode 410. As the polarity of the DC voltage, it is preferable to apply the voltage so that the RF electrode becomes positive. The preferable range of the DC voltage is about 10 to 300V.

In the above-described method for forming a deposited film of the present invention, the following compounds are suitable as the compounds listed as the source gas for silicon deposition.

Specific examples of the gasizable compounds containing silicon atoms include SiH ₄ , Si ₂ H ₆ , and _{Six 4} (X:
Halogen _{atoms), SiXH 3, SiX 2 H} 2, SiX 3 H,
Si ₂ X ₆ , Si ₃ H ₈ , SiD ₄ , SiHD ₃ , SiH
_{2 D 2, SiH 3 D,} SiFD 3, SiF 2 D 2, SiD
₃ H, Si ₂ D ₃ H _{3 and the} like (collectively abbreviated as compound (Si)).

The gasizable compounds containing carbon atoms include CH ₄ , CD ₄ , C _n H _{2n + 2} (n is an integer), C _n H _2n
(N is an _{integer), C n X 2n + 2} (n is an integer, X: halogen atom), C _n X _{2n (n} is an _{integer), C 2 H 2, C} 6 H 6, CO 2,
CO and the like (collectively abbreviated as compound (C)).

[0074] The present invention in at the non-single-crystal Group III ZokuHara element periodic table in order to control valence electrons of the semiconductor layer as a valence electron controlling agent introduced into the non-single-crystal semiconductor layer and Group V atoms and a Group VI atoms.

In the present invention, as a starting material for introducing a group III atom (generically abbreviated as compound (III)), those which can be effectively used, specifically, for introducing a boron atom, B ₂ H ₆ , B ₄ H ₁₀ , B ₅ H ₉ , B ₅ H ₁₁ , B _{6
H 10, B 6 H 12,} B 6 H 14 , etc. borohydride, BF _3, B
Examples include boron halides such as Cl ₃ and BBr _3.
it can. In addition, B ₂ O ₃ , Al (CH ₃ ) ₃ , GaC
l _3, InCl _3, can also be mentioned TlC l _3, and the like.

In the present invention, a starting material for introducing a group V atom (generally abbreviated as compound (V)) is effectively used as a starting material for introducing a phosphorus atom.
₃ , hydrogenated phosphorus such as P ₂ H ₄ , PH ₄ I, PF ₃ , PF ₅ , PC
phosphorus halides such as l ₃ , PCl ₅ , PBr ₃ , PBr ₅ , and PI ₃ ; and oxygen compounds such as P ₂ O ₅ and POCl ₃ . In addition, AsH ₃ , AsF ₃ , AsCl ₃ , AsB
r ₃ , AsF ₃ , SbH ₃ , SbF ₃ , SbF ₅ , SbC
l ₃ , SbCl ₅ , BiH ₃ , BiCl ₃ , BiBr _{3 and the} like can also be mentioned.

[0077] In the present invention, being effectively used as a starting material for the Group VI atoms introduced (abbreviated as collectively compound (VI)) _{is, H 2 S, SF 4,} SF 6, SO ₂ , SO ₂
F ₂ , COS, CS ₂ , H ₂ Se, SeF ₆ , TeH ₂ , T
eF ₆ , (CH ₃ ) ₂ Te, (C ₂ H ₅ ) ₂ Te and the like.

A group III atom, a group V atom and a group VI atom of the periodic table introduced into an i-type layer made of a non-single-crystal semiconductor material.
The preferable introduction amount of the group atom is 1000 ppm or less. In order to achieve the object of the present invention,
In the i-type layer, compensate for both group III and group V atoms, or group III and group VI atoms, or group III, group V and group VI atoms in the periodic table It is preferable to add them as follows.

The compound capable of being gasified is H ₂ , D ₂ ,
The gas may be appropriately diluted with a gas such as He, Ne, Ar, Xe, or Kr and introduced into the deposition chamber. In particular, H ₂ , D ₂ , and He are the most suitable gases for diluting the gasifiable compound.

As the nitrogen-containing gas introduced to make the i-type layer of the non-single-crystal semiconductor layer contain nitrogen, N ₂ , N
H ₃ , ND ₃ , NO, NO ₂ , and N ₂ O (collectively abbreviated as compound (N)) can be given.

The oxygen-containing gas introduced to make the i-type layer of the non-single-crystal semiconductor layer contain oxygen is O ₂ , C
O, CO ₂ , NO, NO ₂ , N ₂ O, CH ₃ CH ₂ OH, C
H ₃ OH and the like (collectively abbreviated as compound (O)).

The stacked structure of the first p (n) -type layer, the n (p) -type layer or the second p (n) -type layer of the photovoltaic device of the present invention is such that the main constituent elements are carbon, oxygen, A layer (A layer) comprising silicon and at least one element selected from nitrogen and containing a Group III element, a Group V element or a Group VI element of the periodic table as a valence electron controlling agent; And a layer (B layer) containing a Group III element, a Group V element, or a Group VI element as a main constituent element.

By using the laminated structure of the present invention for the doping layer, the donor concentration or the acceptor concentration of the doping layer can be improved as compared with the conventional one, and the open-circuit voltage of the photovoltaic element can be increased. Furthermore, the A layer is a material that is not doped at a high concentration (light doping),
And by using a material with a small light absorption coefficient,
Since more light can enter the i-type layer or the pn junction, the short-circuit photocurrent of the photovoltaic element can be improved.

Further, the photovoltaic device having the laminated structure of the present invention can considerably suppress the decrease in photoelectric conversion efficiency even for long-time annealing such as vibration. The detailed mechanism is still unknown, but is considered as follows. In the conventional laminated structure, since the constituent elements are rapidly changing, considerable strain and stress are generated. However, since the layer A of the present invention contains carbon or / and oxygen or / and nitrogen, the generated strain and stress are alleviated inside the layer A, and therefore, even for long-time annealing such as vibration. It is considered that a decrease in photoelectric conversion efficiency can be suppressed.

Further, the photovoltaic device having a laminated structure of the present invention can considerably suppress the decrease in photoelectric conversion efficiency even when irradiated with light for a long time. The detailed mechanism is still unknown, but is considered as follows. When light is irradiated for a long time, a dangling bond is generated inside the A layer, but a part of the valence electron controlling agent contained in the A layer is inactive, and in order to compensate for the generated dangling bond, It is considered that light degradation can be suppressed.

The A layer is made of an amorphous material (denoted as a-), a microcrystalline material (denoted as μc-), a polycrystalline material (denoted as poly-), or a single crystal material (denoted as c-). Consists of

As the amorphous material, for example, a-Si:
H, a-Si: HX, a-SiC: H, a-SiC: H
X, a-SiO: H, a-SiO: HX, a-SiN:
H, a-SiN: HX, a-SiON: H, a-SiO
N: HX, a-SiOCN: H, a-SiOCN: H
X, (X: halogen atom) and the like. As microcrystalline materials, for example, μc-Si: H, μc-SiC:
H, μc-Si: HX, μc-SiC: HX, μc-S
iO: H, μc-SiN: H, μc-SiON: HX,
μc-SiOCN: HX and the like. As the polycrystalline material, for example, poly-Si: H, poly-S
i: HX, poly-SiC: H, poly-SiC:
HX, poly-Si, poly-SiC, etc. are mentioned. As a single crystal material, for example, c-Si, c-Si
C and the like.

When the n (p) -type layer and the second p (n) -type layer have a laminated structure, the A layer is made of a microcrystalline material, a polycrystalline material, a single crystal having a small absorption coefficient of short wavelength light. Materials are preferably used.

In order to form the p-type A layer, a p-type valence electron controlling agent (Group III atoms B and A
l, Ga, In, Tl) to form an n-type A layer, an n-type valence electron controlling agent (group V atom P, As, Sb, Bi or / and / or Group VI atoms (S, Se, Te) are added.

The amount of Group III element in the periodic table added to the p-type A layer, or the Group V atom or the group V atom in the periodic table to the n-type A layer.
The optimum addition amount of the group VI atom is 10 to 10000 ppm.

When the A-type layer is made of a microcrystalline material or a polycrystalline material, hydrogen atoms (H, D) or halogen atoms contained in the A layer compensate for dangling bonds of the A layer. It works and improves the doping efficiency. The number of hydrogen atoms or halogen atoms added to the layer A is zero.
-10 at% is mentioned as the optimum amount. A preferred distribution form includes a large distribution of hydrogen atoms and / or halogen atoms in the vicinity of the interface of the layer A, and the content of hydrogen atoms and / or halogen atoms in the vicinity of the interface is within the bulk. A preferred range is 1.1 to 2.5 times the content. By increasing the content of hydrogen atoms or halogen atoms near the interface in this way, the defect levels and intra-layer stress near the interface are reduced,
Further, mechanical strain can be reduced, and the photovoltaic power and photocurrent of the photovoltaic device of the present invention can be increased.

The layer A preferably has a thickness of 5 to 30 °.

The method for forming the layer A is plasma CVD.
Method, a photo-CVD method and the like, and particularly, a plasma CVD method is suitably used.

When the layer A is formed by these methods, the following gasizable compounds and mixed gases of the compounds can be mentioned as source gases. Specific examples of the gasizable compound containing a silicon atom include the compound (Si) described above. Specific examples of the gasizable compound containing a carbon atom include the compound (C) described above. Examples of the nitrogen-containing gas include the compound (N) described above. Examples of the oxygen-containing gas include the compound (O) described above.

Examples of the substance introduced into the p-type A layer include Group III atoms of the periodic table, and those introduced into the n-type A layer include Group V atoms and Group VI atoms. The compound (III) described above can be used as a starting material for introducing a Group III atom, and B ₂ H ₆ and BF ₃ are particularly suitable.
It is diluted to a desired concentration with a gas such as H ₂ , He, or Ar and stored in a high-pressure cylinder. The compound (V) described above can be effectively used as a starting material for introducing a group V atom. Particularly, PH ₃ and PF ₃ are suitable, and these compounds are usually H ₂ , It is diluted to a desired concentration with a gas such as He or Ar and stored in a high-pressure cylinder. The compound (VI) described above is effectively used as a starting material for introducing a Group VI atom, and H ₂ S is particularly suitable. These compounds are usually H ₂ , He, Ar, and the like. , And store it in a high-pressure cylinder.

When the layer A is formed by the plasma CVD method, the RF plasma CVD method and the microwave plasma CVD method are used.
The method is preferred. When depositing by RF plasma CVD, a capacitively coupled RF plasma CVD is suitable.

When depositing by the RF plasma CVD method,
The substrate temperature in the deposition chamber is 100 to 600 ° C, and the internal pressure is
0.1 to 10 Torr, RF power is 0.01 to 1 W
/ Cm ² , and a deposition rate of 0.1 to 1 ° / sec.

The compounds capable of being gasified are H ₂ , D ₂ ,
The gas may be appropriately diluted with a gas such as He, Ne, Ar, Xe, or Kr and introduced into the deposition chamber.

In particular, when depositing the layer A made of a microcrystalline, polycrystalline, or single-crystal material, the hydrogen gas is preferably used for 2 to 1
It is preferable to dilute the source gas by a factor of 00 and to introduce a relatively high RF power. A suitable range of the RF frequency is 1 MHz to 100 MHz.
In particular, a frequency near 13.56 MHz is optimal.

When depositing by the microwave plasma CVD method, the microwave plasma CVD apparatus uses a dielectric window (alumina ceramics, quartz, boron nitride, etc.) 413 in the deposition chamber.
A method of introducing microwaves through a waveguide via a waveguide is suitable. Although the deposited film forming method of the present invention is also a suitable deposition method, a deposited film applicable to a photovoltaic element can be formed under a wider range of deposition conditions.

Microwave plasma C other than the method of the present invention
When depositing by the VD method, the substrate temperature in the deposition chamber is 100
To 600 ° C., an internal pressure of 0.5 to 30 mTorr, a microwave power of 0.005 to 1 W / cm ³ , and a microwave frequency of 0.5 to 10 GHz. In addition, the compound capable of being gasified is H ₂ , D ₂ , He,
It may be appropriately diluted with a gas such as Ne, Ar, Xe, or Kr and introduced into the deposition chamber.

In particular, when depositing the A layer made of a microcrystalline, polycrystalline, or single-crystal material, the hydrogen gas is preferably used for 2 to 1 hour.
It is preferable to dilute the source gas by a factor of 00 and to introduce a relatively high microwave power.

When the layer A is deposited by the photo-CVD method, a low-pressure mercury lamp is used as a light source and the substrate temperature is 100 to 60.
0 ° C., internal pressure 0.1 to 10 Torr, deposition rate 0.0
The optimum condition is 1 to 1 Å / sec.
You may introduce about ppm.

The compound (Si) includes Si ₂ H ₆ ,
Higher silanes such as Si ₂ H _n X _6-n (X: halogen atom) are preferably used.

The compounds capable of being gasified are H ₂ , D ₂ ,
The gas may be appropriately diluted with a gas such as He, Ne, Ar, Xe, or Kr and introduced into the deposition chamber.

In particular, when depositing the layer A made of a microcrystalline, polycrystalline, or single-crystal material, the hydrogen gas is preferably used for 2 to 1 hours.
It is preferable to dilute and introduce the source gas by a factor of 00.

When the main constituent atom of the B layer is laminated with the p-type A layer, the main constituent atom is a group III atom of the periodic table (for example, B, Al, G).
a, In, and Tl, when laminated with an n-type A layer,
Group V atoms of the periodic table (for example, P, As, Sb, B
i) or / and atoms of group VI of the periodic table (eg S, S
e, Te).

The layer B preferably has a thickness of 5 to 30 °.

As a method for forming the B layer, plasma CVD is used.
Method, a photo-CVD method or the like is preferably used.

When the B layer is formed by these methods, examples of the raw material gas include the following compounds which can be gasified and a mixed gas of the compounds. The compound (III) described above can be effectively used as a starting material for introducing a group III atom.
₂ H ₆ and B (CH ₃ ) ₃ are suitable. The compound (V) described above can be effectively used as a starting material for introducing a group V atom. Effectively used as a starting material for introducing a group VI atom is the compound (V
I).

When the B layer is formed by a plasma CVD method, an RF plasma CVD method and a microwave plasma CVD method are used.
The method is preferred. When depositing by RF plasma CVD, a capacitively coupled RF plasma CVD is suitable.

When depositing by the RF plasma CVD method,
The substrate temperature in the deposition chamber is 100 to 600 ° C, and the internal pressure is
0.1 to 10 Torr, RF power is 0.1 to 2 W /
cm ² and the deposition rate are 0.1 to ² ° / sec as the optimum conditions. Further, the compound which can be gasified may be appropriately diluted with a gas such as H ₂ , D ₂ , He, Ne, Ar, Xe, or Kr and introduced into the deposition chamber.

When depositing by the microwave plasma CVD method, the microwave plasma CVD apparatus uses a dielectric window (alumina ceramics, quartz, boron nitride, etc.) 413 in the deposition chamber.
A method of introducing microwaves through a waveguide via a waveguide is suitable. Although the deposited film forming method of the present invention is also a suitable deposition method, a deposited film applicable to a photovoltaic element can be formed under a wider range of deposition conditions.

Microwave plasma C other than the method of the present invention
When depositing by the VD method, the substrate temperature in the deposition chamber is 100
To 600 ° C., an internal pressure of 0.5 to 30 mTorr, a microwave power of 0.01 to 1 W / cm ³ , and a microwave frequency of 0.5 to 10 GHz. The compounds capable of being gasified are H ₂ , D ₂ , He, N
It may be appropriately diluted with a gas such as e, Ar, Xe, or Kr and introduced into the deposition chamber.

When the layer B is deposited by the photo-CVD method, a low-pressure mercury lamp is used as a light source, and the substrate temperature is 100 to 60.
0 ° C., internal pressure 0.1 to 10 Torr, deposition rate 0.0
1-2 ° / sec is mentioned as the optimum condition.
You may introduce about ppm. Further, the compound which can be gasified may be appropriately diluted with a gas such as H ₂ , D ₂ , He, Ne, Ar, Xe, or Kr and introduced into the deposition chamber.

It is desirable that the laminated structure of the laminated structure used in the photovoltaic element of the present invention starts from the A layer and ends with the A layer. For example, ABA, ABABA, ABABABA
(AB) _n A laminated form, or A ₁ B ₁ A ₂ , A ₁
Etc. _{B 1 A 2 B 2 A 3} , include laminated form of _{(A n B n) A n} +1. However, when a laminated structure is used for the second p (n) -type layer or the third p (n) -type layer in FIG. 17, the layer may start from layer A and end with layer B, for example, AB, ABA
B, ABABAB, etc. (AB) _n laminated form, or A ₁
(A _n B _n ), such as B ₁ , A ₁ B ₁ A ₂ B _{2, and the} like.

Substrate (102) The substrate may be a polycrystalline silicon substrate or a monocrystalline silicon substrate. Further, a polycrystalline silicon layer or a monocrystalline silicon layer may be formed on a support made of an insulating material or a conductive material. A stack of silicon layers may be used.

When using polycrystalline silicon as the substrate,
100-5 ingots produced by the casting method (Latest solar power technology, edited by Yoshihiro Hamakawa, Maki Shoten)
It is sliced to a thickness of about 00 μm and used, or a ribbon-shaped silicon polycrystal made by passing a carbon fiber net through a silicon melt, or polycrystalline silicon is directly obtained from the silicon melt. You may use what cooled slowly while pulling out. In each case,
In order to reduce many trap levels existing in the grain boundary, annealing at a substrate temperature of 500 to 900 ° C. in a hydrogen atmosphere or a substrate temperature of 3 ° C.
It is desirable to perform hydrogen plasma treatment at 00 to 900 ° C. or to irradiate the substrate with a laser beam for annealing.

When using single crystal silicon as the substrate,
Use an ingot produced by the CZ (Chocolarski) method by slicing it to a thickness of about 100 to 500 μm, or use a ribbon-like silicon single crystal produced by passing a carbon fiber net through a silicon melt. Alternatively, a material that is slowly cooled while pulling single crystal silicon directly from a silicon melt may be used.

The conductive support used for laminating a polycrystalline silicon layer or a single crystal silicon layer on a support is, for example, NiCr, stainless steel, Al, Cr,
Mo, Au, Nb, Ta, V, Ti, Pt, Pb, Sn
And alloys thereof.

Similarly, as the electrically insulating support, a film or sheet of synthetic resin such as polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, etc., glass, ceramic,
Paper etc. are mentioned. Preferably, at least one surface of these insulating supports is subjected to conductive treatment, and a polycrystalline silicon layer or a single-crystal silicon layer is provided on the conductive-treated surface side.

For example, in the case of glass, Ni
Cr, Al, Cr, Mo, Ir, Nb, Ta, V, T
i, Pt, Pb, In ₂ O ₃ , ITO (In ₂ O ₃ + SnO
₂ ) Conductivity is imparted by providing a thin film made of NiCr, Al, Ag, Pb, Zn, N
i, Au, Cr, Mо, Ir, Nb, Ta, V, Tl,
A thin metal film such as Pt is provided on the surface by vacuum evaporation, electron beam evaporation, sputtering, or the like, or the surface is laminated with the metal to impart conductivity to the surface. The shape of the support may be a sheet having a smooth surface or an uneven surface. The thickness is appropriately determined so that a desired photovoltaic element can be formed, but when flexibility as a photovoltaic element is required, the thickness is within a range in which the function as a support is sufficiently exhibited. It can be as thin as possible. However, the thickness is usually 10 μm or more from the viewpoints of production and handling of the support, mechanical strength and the like.

In order to form a polycrystalline silicon layer on the surface of the support, a non-single-crystal silicon layer is formed on the support by using a plasma CVD method, a thermal CVD method, a photo CVD method or the like. After that, there is a method of recrystallization by melting with a heater, a laser, an electron beam or the like (S
OI structure formation technology, edited by Shigejiro Furukawa, Industrial Books). Further, there is a method in which fine holes or projections are provided on a support, and these are used as growth nuclei, and a polycrystalline silicon layer is laterally grown by a plasma CVD method, a thermal CVD method, or a photo CVD method. Further, these methods may be used in combination.

In order to make the conductivity type of these layers p-type, a group III atom of the periodic table is added at a high concentration, and to make it n-type, a group V or / and VI atom of the periodic table is added. May be added at a high concentration. When forming these layers, the compound (Si)
At the same time, the compound (III), the compound (V), and / or the compound (VI) may be introduced into the deposition chamber, or may be added by ion implantation after forming these layers. Basically, it is the same as the method for forming a first p (n) type layer described later.

In order to increase the efficiency of collecting incident light, it is desirable to make the surface of the plate uneven (textured). To perform texture processing, 100 to 130
Immersion in hydrazine aqueous solution of 50-70% for 10 minutes or 90-120 ° C, 0.5-3% of NaOH
It may be immersed in an aqueous solution for about 5 minutes.

Back electrode (101) Ni, Au, Ti, Pd, Ag, A
Metals such as l, Cu, and AlSi, which have high reflectance from visible light to near infrared and can form a good ohmic contact with silicon, or alloys thereof are suitable. These metals are desirably formed by a vacuum deposition method, a sputtering method, a plating method, a printing method, or the like.

For example, when formed by a vacuum evaporation method, Ti-Ag or Ti-Pd-
Ag or Ti-Ni-Cu is suitable, and Al is suitable for a p-type silicon substrate. In the case of forming by a plating method, Ni, Al, or Cr is suitable, and by performing a sintering process at 300 ° C. after the plating process, a better ohmic contact can be obtained. In order to lower the series resistance of the electrode, Cu may be finally plated. In the case of forming by a printing method, an Ag paste is printed on an n-type silicon substrate and an Al paste is printed on a p-type silicon substrate with a screen printer, and thereafter, good contacts are obtained by sintering. . The thickness of these metals is 10 nm.
To 5000 nm is a suitable layer thickness. In order to make the surface of these metals uneven (texture), the substrate temperature at the time of depositing these metals may be 200 ° C. or higher.

First p (n) -type layer (103) The first p (n) -type layer is an important layer that affects the characteristics of the photovoltaic element. The details of the case of the laminated structure are as described above, and the case of the single layer will be described below.

The first p (n) type layer is made of a microcrystalline material (μc
-), Or a polycrystalline material (poly-), or a single-crystalline material (c-).

As microcrystalline material, for example, μc-S
i: H, μc-SiC: H, μc-Si: HX, μc-
SiC: HX, μc-SiGe: H, μc-SiO:
H, μc-SiGeC: H, μc-SiN: H, μc −
SiON: HX, μc-SiOCN: HX, etc. (X: halogen atom).

As the polycrystalline material, for example, poly-S
i: H, poly-Si: HX, poly-SiC:
H, poly-SiC: HX, poly-1y-SiGe:
H, poly-Si, poly-SiC, poly-S
iGe and the like.

As the crystal material, for example, c-Si, c-
SiC, c-SiGe and the like can be mentioned.

In order to form the first p-type layer, a p-type valence electron controlling agent (Group III atom B, Al, Ga, In,
Tl) is added in high concentration. In order to form the first n-type layer, an n-type valence electron controlling agent (Group V atoms P, A in the periodic table)
s, Sb, Bi, group VI atoms from the periodic table S, Se, Te)
At a high concentration.

The addition amount of Group III atoms of the periodic table to the first p-type layer or the addition amount of Group V and VI atoms of the periodic table to the first n-type layer is 0.1 to 10 at%. Is an optimal amount.

In addition, the first p (n) -type layer is made of a microcrystalline material,
Alternatively, when it is made of a polycrystalline material, the first p
Hydrogen atoms (H, D) or halogen atoms contained in the (n) -type layer work to compensate for dangling bonds of the p-type layer or the n-type layer and improve the doping efficiency of the p-type layer or the n-type layer. Things. The optimum amount of hydrogen atoms or halogen atoms added to the p-type layer or the n-type layer is 0 to 10 at%. Content of hydrogen atoms and / or halogen atoms at the interface side between the first p (n) type layer and the n (p) type substrate and at the interface side between the first p (n) type layer and the n (p) type layer Are preferred distribution forms, and the content of hydrogen atoms and / or halogen atoms in the vicinity of the interface is preferably in a range of 1.3 to 2.5 times the content in the bulk. It is listed as. As described above, hydrogen or halogen atoms are contained at the interface between the first p (n) -type layer and the n (p) -type substrate or near the interface between the first p (n) -type layer and the n (p) -type layer. By increasing the amount, the defect level near the interface and the intra-layer stress can be reduced, and further, the mechanical strain can be reduced, and the photovoltaic power and the photocurrent of the photovoltaic device of the present invention can be increased. Can be.

The electric characteristics of the first p (n) -type layer of the photovoltaic element are preferably those having an activation energy of 0.2 eV or less, and those having an activation energy of 0.1 eV or less are optimal. The specific resistance is preferably 100 Ωcm or less, and 1 Ωcm
The following are optimal. Further, the layer thickness of the p-type layer and the n-type layer is 5
0-2000 ° is preferred.

As a method of forming the first p (n) type layer, there are a method of depositing a thin film layer and a method of mixing impurities from the surface of the n (p) substrate.

As a method for forming a thin film layer, plasma C
There are a VD method, a thermal CVD method, an optical CVD method, and the like. As a method of mixing impurities into the substrate, a gas diffusion method, a solid phase diffusion method, an ion implantation method, and the like are used. Method and gas diffusion method are preferably used.

When the first p (n) -type layer is formed by the plasma CVD method, as a source gas, a gasizable compound containing a silicon atom, a gasizable compound containing a carbon atom, and the like, Can be mentioned.

Specific examples of the gasizable compound containing a silicon atom include the compound (Si) described above. Specific examples of the gasizable compound containing a carbon atom include the compound (C) described above. Examples of the nitrogen-containing gas include the compound (N) described above.
Examples of the oxygen-containing gas include the compound (O) described above.

In order to control valence electrons, a substance introduced into the first p-type layer is a Group III atom of the periodic table, and an atom introduced into the first n-type layer is a Group V atom and Group VI atoms.

The compound (III) described above can be effectively used as a starting material for introducing a group III atom, and B ₂ H ₆ and BF ₃ are particularly suitable.
The compound (V) described above can be effectively used as a starting material for introducing a group V atom.
H ₃ and PF ₃ are suitable. The compound (VI) described above is effectively used as a starting material for introducing a group VI atom, and H ₂ S is particularly suitable. These compounds are usually diluted to a desired concentration with a gas such as H ₂ , He, or Ar and stored in a high-pressure cylinder.

When the first p (n) -type layer is formed by the plasma CVD method, the RF plasma CVD method and the microwave plasma CVD method are preferable. When depositing by RF plasma CVD, a capacitively coupled RF plasma CVD is suitable.

When depositing by the RF plasma CVD method,
The substrate temperature in the deposition chamber is 100 to 600 ° C, and the internal pressure is
0.1-10 Torr, RF power is 0.01-5.
The optimum conditions are 0 W / cm ² and the deposition rate is 0.1 to 30 ° / sec. Further, the gasifiable compound may be appropriately diluted with a gas such as H ₂ , He, Ne, Ar, Xe, or Kr and introduced into the deposition chamber.

In particular, when depositing a layer having a small light absorption such as μc-Si: H or μc-SiC: H or a layer having a wide band gap, the source gas is diluted 2 to 100 times with hydrogen gas, and the RF power is reduced. It is preferable to introduce a relatively high power. RF frequency is 1MHz ~ 1
00 MHz is a suitable range, especially 13.56 MHz
Nearby frequencies are optimal.

When depositing by the microwave plasma CVD method, the microwave plasma CVD apparatus uses a dielectric window (alumina ceramics, quartz, boron nitride, etc.) 413 in the deposition chamber.
A method of introducing microwaves through a waveguide via a waveguide is suitable. Although the deposited film forming method of the present invention is also a suitable deposition method, a deposited film applicable to a photovoltaic element can be formed under a wider range of deposition conditions.

Microwave plasma C other than the method of the present invention
When depositing by the VD method, the substrate temperature in the deposition chamber is 100
To 600 ° C., an internal pressure of 0.5 to 30 mTorr, a microwave power of 0.005 to 1 W / cm ³ , and a microwave frequency of 0.5 to 10 GHz. Further, the compounds capable of being gasified are H ₂ , He, N
It may be appropriately diluted with a gas such as e, Ar, Xe, or Kr and introduced into the deposition chamber.

Especially, μc-Si: H, μc-SiC: H,
When depositing a layer having a small bandgap such as μc-SiO: H or μc-SiN: H, the source gas is diluted 2 to 100 times with hydrogen gas, and the microwave power is relatively high. Is preferably introduced.

When the first p-type layer is formed by gas diffusion, the temperature of the n-type substrate is set at 800 to 950 ° C., a diffusion gas is introduced into the deposition chamber, and the group III atoms of the periodic table are deposited on the substrate. To spread. As the diffusion gas, the compound (II
I), and BCl ₃ and BBr ₃ are particularly suitable.

In the case of forming the first n-type layer by the gas diffusion method, the temperature of the p-type substrate is set at 800 to 950 ° C., a diffusion gas is introduced into the deposition chamber, and a group V atom of the periodic table or The group VI atoms diffuse into the substrate. As the diffusion gas, the above-mentioned compound (V) or compound (VI) can be mentioned, and POCl ₃ and P ₂ O ₅ are particularly suitable.

In the case where the first p-type layer is formed by ion implantation,
The group III atoms of the periodic table are accelerated under a high electric field and n
Irradiates the mold substrate surface and implants III atoms into the substrate
You. For example, when boron is implanted, 1 × 10¹⁵~ 1
0x10¹⁵(Pcs / cm^Two)of^ll B⁺About 5 to 50 keV
It is good to perform at the acceleration voltage.

When the first n-type layer is formed by an ion implantation method, a group V atom or a group VI atom of the periodic table is accelerated under a high electric field, and the surface of the n-type substrate is irradiated. Group atom,
Alternatively, Group VI atoms are implanted into the substrate. For example, when phosphorus is injected, 0.5 to 10 × 10 ¹⁵ (pieces / cm
² ) ³¹ P ⁺ is preferably performed at an acceleration voltage of about ¹ to 10 keV.

The n (p) type layer (104) and the second p
(N) -type layer (106 ) The n (p) -type layer and the second p (n) -type layer are important layers that affect the characteristics of the photovoltaic element. The case of a laminated structure is as described above, and here, the case of a single layer structure will be described.

An n (p) type layer made of a non-single crystal material, a second
Examples of the p (n) type layer include an amorphous material (abbreviated as a-), a microcrystalline material, and a polycrystalline material.

As the amorphous material, for example, a-Si:
H, a-Si: HX, a-SiC: H, a-SiC: H
X, a-SiGe: H, a-SiGeC: H, a-Si
O: H, a-SiN: H, a-SiON: HX, a-S
iOCN: HX and the like. Μ as microcrystalline material
c-Si: H, μc-SiC: H, μc-Si: HX,
μc-SiC: HX, μc-SiGe: H, μc-Si
O: H, μc-SiGeC: H, μc-SiN: H, μ
c-SiON: HX, μc-SiOCN: HX and the like.

As the polycrystalline material, for example, poly-S
i: H, poly-Si: HX, poly-SiC:
H, poly-SiC: HX, poly-SiGe:
H, poly-Si, poly-SiC, poly-S
iGe and the like.

In order to make the conductivity type p-type, a p-type valence electron controlling agent (group III atom B, Al, Ga, In, T
l) is added in high concentration to the above material. Further, in order to make the conductivity type n-type, an n-type valence electron controlling agent (atoms P, As, Sb, and V, S, Se, and V in the periodic table).
Te) is added in high concentration in the above material.

In particular, the second p (n) -type layer is made of a microcrystalline material having a small light absorption or a non-single crystalline material having a wide band gap, for example, μc-Si: H, μc-Si
C: H, μc-Si: HX, μc-SiC: HX, μc
-SiO: H, μc-SiN: H, μc-SiON: H
X, μc-SiOCN: HX, poly-Si: H, p
poly-Si: HX, poly-SiC: H, poly
-SiC: HX, poly-Si, poly-SiC,
a-SiC: H, a-SiC: HX, a-SiO: H,
a-SiN: H, a-SiОN: HX, a-SiОC
N: HX or the like is suitable.

Periodic Table III of the p-type layer and the second p-type layer
The addition amount of the group atom and the addition amount of the group V atom and the group VI of the periodic table to the n-type layer and the second n-type layer are 0.1 to 50 a.
t% is mentioned as the optimum amount.

A hydrogen atom (H, D) or a halogen atom contained in the n (p) -type layer and the second p (n) -type layer functions to compensate for dangling bonds, thereby improving doping efficiency. The optimum amount is 0.1 to 40 at%. In particular, when the n (p) -type layer and the second p (n) -type layer are made of a microcrystalline material or a polycrystalline material, the optimal amount of hydrogen atoms or halogen atoms is 0.1 to 10 at%.
Further, those having a large content of hydrogen atoms and / or halogen atoms at each interface side of the n (p) -type layer / i-type layer and the second p (n) -type layer / i-type layer are preferable. The content of hydrogen atoms and / or halogen atoms near the interface is preferably in a range of 1.1 to 2 times the content in the bulk. Thus n
By increasing the content of hydrogen atoms or halogen atoms in the vicinity of each interface between the (p) -type layer / i-type layer and the second n (p) -type layer / i-type layer, defect levels and films near the interfaces are obtained. Internal stress can be reduced, mechanical strain can be reduced, and the photovoltaic power and photocurrent of the photovoltaic device of the present invention can be increased.

The electrical characteristics of the n (p) -type layer and the second p (n) -type layer preferably have an activation energy of 0.2 eV or less, and most preferably have an activation energy of 0.1 eV or less. The specific resistance is preferably 100 Ωcm or less, and 1 Ωcm
The following are optimal. Further, the layer thickness of the n (p) type layer is 10 to
1000 ° is preferred, 30-300 ° is optimal,
The layer thickness of the second p (n) -type layer is preferably from 10 to 500 °, and most preferably from 30 to 200 °.

As a method for forming the n (p) type layer and the second p (n) type layer, a plasma CVD method, a thermal CVD method, a light CV
The D method or the like is used, and particularly, the plasma CVD method is suitably used.

When the n (p) -type layer and the second p (n) -type layer are formed by the plasma CVD method, the gaseous compound containing silicon atoms and the gaseous gas containing carbon atoms are used as source gases. The compound to be obtained and the mixed gas of the compound can be mentioned. Specific examples of the gasizable compound containing a silicon atom include the aforementioned compound (S
i). Specific examples of the gasizable compound containing a carbon atom include the compound (C) described above. Examples of the nitrogen-containing gas include the compound (N) described above. Examples of the oxygen-containing gas include the compound (O) described above.

Examples of the substance introduced into the p-type layer or the n-type layer for controlling valence electrons include Group III, V, and VI atoms of the periodic table.

The compound (III) described above can be effectively used as a starting material for introducing a group III atom. Particularly, B ₂ H ₆ and BF ₃ are suitable.

The compound (V) described above can be effectively used as a starting material for introducing a group V atom. Particularly, PH ₃ , PF ₃ and PF ₅ are suitable. VI
Effectively used as a starting material for introducing a group atom is
The compound (VI) described above is exemplified.

The deposition methods preferably used as the plasma CVD method are the RF plasma CVD method and the microwave plasma CVD method. When depositing by RF plasma CVD, a capacitively coupled RF plasma CVD is suitable.

When depositing by the RF plasma CVD method,
The substrate temperature in the deposition chamber is 100 to 450 ° C., and the internal pressure is
0.1-10 Torr, RF power is 0.01-5.
The optimum conditions are 0 W / cm ² and the deposition rate is 0.1 to 30 ° / sec. RF frequency is 1M
Hz to 100 MHz is a suitable range, especially 13.5.
A frequency near 6 MHz is optimal. Further, the gasifiable compound may be appropriately diluted with a gas such as H ₂ , He, Ne, Ar, Xe, or Kr and introduced into the deposition chamber.

In particular, μc-Si: H, μc-SiC:
H, μc-Si: HX, μc-SiC: HX, μc-S
iO: H, μc-SiN: H, μc-SiON: HX,
μc-SiOCN: HX, poly-Si: H, pol
y-Si: HX, poly-SiC: H, poly-S
iC: HX, poly-Si, poly-SiC: H,
a-SiC: H, a-SiC: HX, a-SiΟ: H,
a-SiN: H, a-SiΟN: HX, a-SiΟC
In the case of depositing a microcrystalline layer, a polycrystalline layer, or an amorphous layer having a wide band gap, such as N: HX, which has low light absorption, the source gas is diluted 2 to 100 times with hydrogen gas, and the RF power is relatively high. It is preferable to introduce high power.

In the case of depositing by a microwave plasma CVD method, a method of introducing a microwave into a deposition chamber through a waveguide through a dielectric window is suitable for a microwave plasma CVD apparatus. Although the deposited film forming method of the present invention is also a suitable deposition method, a deposited film applicable to a photovoltaic element can be formed under a wider range of deposition conditions.

Microwave plasma C other than the method of the present invention
When depositing by the VD method, the substrate temperature in the deposition chamber is 100
To 450 ° C., an internal pressure of 0.5 to 30 mTorr, a microwave power of 0.005 to 1 W / cm ³ , and a microwave frequency of 0.5 to 10 GHz.

The compounds capable of being gasified are H ₂ , H
It may be appropriately diluted with a gas such as e, Ne, Ar, Xe, or Kr and introduced into the deposition chamber.

In particular, μc-Si: H, μc-SiC:
H, μc-Si: HX, μc-SiC: HX, μc-S
iO: H, μC-SiN: H, μc-SiON: HX,
μc-SiOCN: HX, poly-Si: H, pol
y-Si: HX, poly-SiC: H, poly-S
iC: HX, poly-Si, poly-SiC: H,
a-SiC: H, a-SiC: HX, a-SiO: H,
a-SiN: H, a-SiON: HX, a-SiOC
N: When depositing a microcrystalline layer, a polycrystalline layer, or an amorphous layer having a wide band gap, such as HX, which has low light absorption, dilute the source gas by 2 to 100 times with hydrogen gas, and compare the microwave power. It is preferable to introduce extremely high power.

I-Type Layer (105 ) In the photovoltaic device of the present invention, the i-type layer is the most important layer for generating and transporting carriers with respect to irradiation light.

As the i-type layer, a slightly p-type and slightly n-type layer can be used.

As the i-type layer of the photovoltaic device of the present invention,
The band gap changes smoothly in the thickness direction of the i-type layer containing silicon atoms and carbon atoms, and the minimum value of the band gap is shifted toward the p / i interface from the center position of the i-type layer. Moreover, and a valence electron controlling agent as a valence electron control agent and an acceptor which serves as a donor are both doped to the i-type layer.

The hydrogen atoms (H, D) or the halogen atoms (X) contained in the i-type layer work to compensate for dangling bonds of the i-type layer, and the carrier mobility and lifetime of the carrier in the i-type layer. To improve the product of Further, it functions to compensate for the interface state of each interface of the n (p) -type layer / i-type layer and the second p (n) -type layer / i-type layer. And it has the effect of improving the light responsiveness. The number of hydrogen atoms and / or halogen atoms contained in the i-type layer is 1 to 30.
at% is mentioned as the optimum content.

In particular, the n (p) type layer / i type layer, the second p
A preferred distribution form includes a large distribution of hydrogen atoms and / or halogen atoms at each interface side of the (n) -type layer / i-type layer, and a hydrogen atom and / or halogen near the interface is preferred. The preferred range of the content of atoms is 1.1 to 2 times the content in the bulk.

Further, it is preferable that the content of hydrogen atoms and / or halogen atoms is changed contrary to the increase and decrease of the content of silicon atoms. The content of the hydrogen atom or the halogen atom at the position where the content of the silicon atom is the maximum is preferably in the range of 1 to 10 at%, and 0.3% of the maximum region of the content of the hydrogen atom or the halogen atom.
0.8 times is a preferable range.

In the i-type layer of the photovoltaic device of the present invention, it is desirable that the content of hydrogen atoms and / or halogen atoms be small where there are many silicon atoms, and large where there are few silicon atoms. That is, corresponding to the band gap, the content of the hydrogen atom or / and the halogen atom is small where the band gap is narrow, and the hydrogen atom or / and / or the content of the halogen atom is small where the band gap is wide.
And the content of halogen atoms is desirably increased. Although the details of the mechanism are unknown, according to the method for forming a deposited film of the present invention, in the deposition of an alloy semiconductor containing silicon atoms and carbon atoms, each of them depends on the difference in the ionization rate of silicon atoms and carbon atoms. It is considered that a difference occurs in the RF energy obtained by the atoms, and as a result, even if the hydrogen content or / halogen content in the alloy-based semiconductor is small, the relaxation is sufficiently advanced and a good-quality alloy-based semiconductor can be deposited.

In addition, by adding trace amounts of oxygen and / or nitrogen to the i-type layer containing silicon atoms and carbon atoms in a trace amount of 1000 ppm or less, the durability of the photovoltaic element against annealing due to long-term vibration is improved. It becomes. The exact cause is unknown, but
Since the composition ratio of silicon atoms and carbon atoms changes continuously in the layer thickness direction, the residual strain tends to increase more than when silicon atoms and carbon atoms are mixed at a fixed ratio. Conceivable. By adding oxygen atoms and / or nitrogen atoms to such a system, the structural strain can be reduced, and as a result, the photovoltaic device has good durability against annealing due to long-term vibration. It is considered to be. As the distribution of oxygen atoms and / or nitrogen atoms in the layer thickness direction, a distribution that increases or decreases in accordance with the content of carbon atoms is preferable. This distribution is a distribution corresponding to the distribution of hydrogen atoms and / or halogen atoms, but such a distribution is considered to be preferable in view of the effect of removing structural distortion and the effect of reducing dangling bonds.

Further, by distributing such hydrogen atoms (or / and halogen atoms) and oxygen atoms (or / and nitrogen atoms), the tail states of the valence band and the conduction band are smoothly and continuously connected. It is.

The thickness of the i-type layer greatly depends on the structure of the photovoltaic element (for example, single cell, tandem cell, triple cell) and the band gap of the i-type layer.
1.0 μm is mentioned as the optimum layer thickness.

The i-type layer containing silicon atoms and carbon atoms according to the method of forming a deposited film of the present invention has a deposition rate of 2.5 n.
Even if the speed is increased to m / sec or more, the tail state on the valence band side is small, and the tilt of the tail state is 60 m.
The density is less than eV and the density of dangling bonds by electron spin resonance (ESR) is 10 ¹⁷ / cm ³ or less.

It is preferable that the band gap of the i-type layer is designed to be wide at each interface side of the n (p) -type layer / i-type layer and the second p (n) -type layer / i-type layer. It is. By designing in this manner, the photovoltaic power and the photocurrent of the photovoltaic element can be increased, and furthermore, the reduction of the photoelectric conversion efficiency (light deterioration) when irradiated with light for a long time can be suppressed. it can. The method for forming a deposited film by the microwave plasma CVD method of the present invention is most suitable for the i-type layer of the photovoltaic element.

Transparent Electrode (107 ) As the transparent electrode, a transparent electrode of indium oxide or indium-tin oxide is suitable. The transparent electrode is deposited as follows.

For deposition of the transparent electrode, sputtering and true
Empty deposition is the optimal deposition method. Sputtering equipment
A transparent electrode made of indium oxide on the substrate
When deposited on a target, the target is metallic indium (In)
And indium oxide (In_Two O_Three)
Can be

When a transparent electrode made of indium-tin oxide is further deposited on a substrate, the target may be metal tin, metal indium or an alloy of metal tin and metal indium,
Targets such as tin oxide, indium oxide, and indium-tin oxide are used in appropriate combination.

When depositing by the sputtering method, the substrate temperature is an important factor, and a preferable range is from 25 ° C. to 600 ° C. Also, when depositing a transparent electrode by a sputtering method, as a sputtering gas,
An inert gas such as an argon gas (Ar), a neon gas (Ne), a xenon gas (Xe), and a helium gas (He) is exemplified, and an Ar gas is particularly suitable. It is preferable to add oxygen gas (O ₂ ) to the inert gas as needed. Particularly when a metal is targeted, oxygen gas (O ₂ ) is essential.

Further, when sputtering the target with the inert gas or the like, the pressure in the discharge space is set to 0.1 to 50 mTorr in order to perform sputtering effectively.
Is a preferred range.

In addition, as a power source in the case of the sputtering method, a DC power source or an RF power source is suitable. 10 to 1000 W as electric power during sputtering
Is a suitable range.

The deposition rate of the transparent electrode depends on the pressure in the discharge space and the discharge power.
It is in the range of 1 to 10 nm / sec.

It is preferable that the thickness of the transparent electrode is deposited so as to satisfy the condition of the antireflection film. As a specific layer thickness of the transparent electrode, a preferable range is 50 to 300 nm.

Examples of a deposition source suitable for depositing a transparent electrode in a vacuum deposition method include metal tin, metal indium, and an indium-tin alloy.

The substrate temperature for depositing the transparent electrode is preferably in the range of 25 ° C. to 600 ° C.

Further, when depositing a transparent electrode, the pressure in the deposition chamber is reduced to 10 ⁻⁶ Torr or less, and then oxygen gas (O ₂ ) is supplied to the deposition chamber in a range of 5 × 10 ⁻⁵ Torr to 9 × 10 ⁻⁴ Torr. It is necessary to introduce. By introducing oxygen in this range, the metal vaporized from the evaporation source reacts with oxygen in the gas phase to deposit a good transparent electrode.

Further, plasma may be generated by introducing RF power at the above-mentioned degree of vacuum, and vapor deposition may be performed via the plasma.

A preferable range of the deposition rate of the transparent electrode under the above conditions is 0.01 to 10 nm / sec.
When the deposition rate is less than 0.01 nm / sec, the productivity is reduced. When the deposition rate is more than 10 nm / sec, the film becomes a coarse film, and the transmittance, the conductivity and the adhesion are reduced.

Current collecting electrode (108 ) The material and forming method of the current collecting electrode are basically the same as those of the back electrode. However, in order to make light efficiently enter the i-type layer, which is a photovoltaic layer, and efficiently collect generated carriers on the electrode, the shape of the current collecting electrode (the shape as viewed from the light incident direction) and the material are important. It is. Usually, the shape of the collecting electrode is a comb shape, and the line width, the number of lines, and the like are determined by the shape and size of the photovoltaic element viewed from the light incident direction, the material of the collecting electrode, and the like. Line width is usually 0.1mm-5mm
It is about. The material is usually Ag, Cu,
Ai, Cr, etc. are used.

Next, the power generation system of the present invention will be described.

The power generation system of the present invention comprises the above-described photovoltaic element of the present invention, and monitors the voltage and / or current of the photovoltaic element and supplies the battery and / or an external load with the photovoltaic element. The control system includes a control system for controlling power supply and a storage battery for storing power from the photovoltaic element and / or supplying power to an external load.

FIG. 18 shows an example of a power supply system of the present invention, which is a basic circuit for charging and supplying power using a photovoltaic element. In this circuit, the photovoltaic element of the present invention is used as a solar cell module, and a backflow prevention diode (C
D), a voltage control circuit (constant voltage circuit) for monitoring the voltage and controlling the voltage, a storage battery, a load, and the like.

As a backflow prevention diode, a germanium diode, a silicon diode, a Schottky diode or the like is suitable. Examples of the storage battery include a nickel cadmium battery, a rechargeable silver oxide battery, a lead storage battery, and a flywheel energy storage unit.

The voltage control circuit is almost equal to the output of the solar cell until the battery is fully charged, but when the battery is fully charged, the charging current is stopped by the charge control IC.

A solar cell system utilizing such photovoltaic power can be used as a power source for a battery charging system for a car, a battery charging system for a ship, a streetlight lighting system, an exhaust system, and the like.

As described above, the power supply system using the photovoltaic element of the present invention as a solar cell can be used stably for a long period of time, and even when the irradiation light applied to the solar cell fluctuates. Since it functions sufficiently as an electromotive element, it shows excellent stability.

[0207]

EXAMPLES Hereinafter, the electromotive force element of the present invention will be described in detail by manufacturing a solar cell, but the present invention is not limited to this.

Example 1 In this example, an n-type polycrystalline silicon substrate manufactured by the casting method was used to manufacture the solar cell shown in FIG. 1 in which the i-type layer contained P and B atoms. .

A 50 × 50 mm ² substrate is made of HF and HNO
₃ Dipped in an aqueous solution (diluted to 10% with H ₂ O) for several seconds and washed with pure water. Next, the substrate was ultrasonically washed with acetone and isopropanol, further washed with pure water, and dried with warm air.

Next, the source gas supply device 200 shown in FIG.
A semiconductor layer was formed on a substrate by a manufacturing apparatus using a glow discharge decomposition method including a deposition apparatus 400 and a deposition apparatus 400. Hereinafter, the manufacturing procedure will be described.

The gas cylinders 2041 to 2047 in the figure are sealed with a source gas for producing the photovoltaic device of the present invention, and 2041 is a SiH ₄ gas (purity 99.
999%) cylinder, 2042 is CH ₄ gas (purity: 99.99%).
9999%) cylinder, 2043 is H ₂ gas (purity 99.99%).
9999%) cylinder, 2044 is 100pp with H ₂ gas
m3, a PH ₃ gas (purity 99.99%, hereinafter abbreviated as “PH ₃ / H ₂ ”) cylinder, and 2045 a B ₂ H ₆ gas (purity 99.99%) diluted with H ₂ gas to 100 ppm.
99%, hereinafter abbreviated as “B ₂ H ₆ / H ₂ ”)
046 is NH ₃ gas (purity 9) diluted to 1% with H ₂ gas.
9.9999%, hereinafter abbreviated as "NH ₃ / H ₂ ") cylinder, 2047 is O ₂ gas (purity 99.9999%, hereinafter abbreviated as “O ₂ / He”) diluted to 1% with He gas. ) It is a cylinder. In advance, gas cylinders 2041 to 204
7 when installing each gas,
Introduced into the gas pipe up to 2027, the pressure regulator 203
Each gas pressure was adjusted to ² kg / cm ² by 1 to 2037.

Next, the back surface of the substrate 404 is
05, the leak valve 409 of the deposition chamber 401 is closed, the conductance valve 407 is fully opened, the interior of the deposition chamber 401 is evacuated by a vacuum pump (not shown), and the vacuum gauge 402 reads about 1 × 10 ^−4. When the pressure reaches Torr, the valves 2001 to 2007 and the auxiliary valve 408 are opened, the inside of the gas pipe is evacuated, and when the reading of the vacuum gauge 402 reaches about 1 × 10 ⁻⁴ Torr, the valve 200 is restored.
1 to 2007 are closed, 2031 to 2037 are gradually opened, and each gas is supplied to the mass flow controller 2011 to 2011.
2017. The mixing of the SiH ₄ gas and the CH ₄ gas was performed at a distance of 0.5 m from the deposition chamber.

After the preparation for film formation is completed as described above, the substrate 404 is subjected to a hydrogen plasma treatment to form a first p-type layer, an n-type layer, an i-type layer, and a second p-type layer on the substrate. Was formed. The procedure is described below.

To perform the hydrogen plasma treatment, the valve 20
03 was gradually opened, H ₂ gas was introduced into the deposition chamber 401, and the mass flow controller 2013 adjusted the flow rate of H ₂ gas to 500 sccm. The conductance valve was adjusted while watching the vacuum gauge 402 so that the pressure in the deposition chamber became 2.0 Torr, and the heater 405 was set so that the temperature of the substrate 404 became 600 ° C.
When the substrate temperature becomes stable, confirm that the shutter is closed.
W / cm ³ was set, microwave power was introduced into the deposition chamber through the dielectric window to generate glow discharge, the shutter 415 was opened, and hydrogen plasma treatment of the substrate 404 was started. After 10 minutes, the shutter was closed, the microwave power was turned off, the glow discharge was stopped, and the hydrogen plasma treatment was completed. After continuously flowing the H ₂ gas into the deposition chamber 401 for 5 minutes, the valve 2003 was closed and the inside of the deposition chamber 401 and the inside of the gas pipe were evacuated.

To form the first p-type layer, the valve 20
03 was gradually opened, H ₂ gas was introduced into the deposition chamber 401, and the mass flow controller 2013 adjusted the H ₂ gas flow rate to 50 sccm. The conductance valve is adjusted while watching the vacuum gauge 402 so that the pressure in the deposition chamber becomes 2.0 Torr.
The heater 405 is set to 50 ° C., and when the substrate temperature is stabilized, the valves 2001 and 200 are further increased.
5 was gradually opened, and SiH ₄ gas and B ₂ H ₆ / H ₂ gas were allowed to flow into the deposition chamber 401. At this time, the flow rate of the SiH ₄ gas was 5 sccm, the flow rate of the H ₂ gas was 100 sccm, and B ₂ H ₆
Each of the mass flow controllers was adjusted so that the / H ₂ gas flow rate was 500 sccm. The opening of the conductance valve 407 was adjusted while watching the vacuum gauge 402 so that the pressure in the deposition chamber 401 became 2.0 Torr.
Confirm that the shutter 415 is closed,
The power supply was set to 0.20 W / cm ³ , RF power was introduced, glow discharge occurred, shutter 415 was opened,
The formation of the first p-type layer on the substrate was started. Layer thickness 100n
When the first p-type layer of m is formed, the shutter is closed,
The RF power was turned off, glow discharge was stopped, and the formation of the first p-type layer was completed. The valves 2001 and 2005 are closed to stop the flow of the SiH ₄ gas and the B ₂ H ₆ / H ₂ gas into the deposition chamber 401, and the H ₂ gas is allowed to flow into the deposition chamber 401 for 5 minutes. Was closed, and the inside of the deposition chamber 401 and the inside of the gas pipe were evacuated.

In order to form the n-type layer, the auxiliary valve 40
8. Open the valve 2003 gradually, introduce H ₂ gas into the deposition chamber 401 through the gas introduction pipe 411, set the mass flow controller 2013 so that the H ₂ gas flow rate becomes 50 sccm, and set the pressure in the deposition chamber to 1 .0Tor
r with the conductance valve so that the substrate 4
Heater 405 so that the temperature of 04 becomes 350 ° C.
It was set. When the substrate temperature was stabilized, the valves 2001 and 2004 were gradually opened, and SiH ₄ gas and
PH ₃ / H ₂ gas was flowed into the deposition chamber 401. At this time, the flow rate of the SiH ₄ gas was ₂ sccm, and the flow rate of the H ₂ gas was 10 sccm.
Each mass flow controller was adjusted so that the flow rate of the PH ₃ / H ₂ gas was 200 sccm at 0 sccm.
The opening of the conductance valve 407 was adjusted so that the pressure in the deposition chamber 401 became 1.0 Torr. The power of the RF power source was set to 0.01 W / cm ³ ,
0, RF power is introduced, a glow discharge is generated, a shutter is opened, and an n-type layer is formed on the first p-type layer.
When the n-type layer having a thickness of 30 nm was formed, the shutter was closed, the RF power was turned off, the glow discharge was stopped, and the formation of the n-type layer was completed. The valves 2001 and 2004 are closed to stop the flow of the SiH ₄ gas and the PH ₃ / H ₂ gas into the deposition chamber 401, and the H ₂ gas is continuously flown into the deposition chamber 401 for 5 minutes. After closing, the inside of the deposition chamber 401 and the inside of the gas pipe were evacuated.

Next, in order to form an i-type layer, the valve 20 was used.
03 was gradually opened, H ₂ gas was introduced into the deposition chamber 401, and the mass flow controller 2013 adjusted the H ₂ gas flow rate to 300 sccm. The conductance valve is adjusted so that the pressure in the deposition chamber becomes 0.01 Torr, and the heater 405 is set so that the temperature of the substrate 404 becomes 350 ° C. When the substrate temperature is stabilized, the valves 2001, 2002, 2004, and 20
05 is gradually opened, and SiH ₄ gas, CH ₄ gas, PH ₃
/ H ₂ gas and B ₂ H ₆ / H ₂ gas flowed into the deposition chamber 401. At this time, the flow rate of the SiH ₄ gas is 100 sccm,
H ₄ gas flow rate 30 sccm, H ₂ gas flow rate 300 sccc
m, PH ₃ / H ₂ gas flow rate was adjusted to ₂ sccm and B ₂ H ₆ / H ₂ gas flow rate was adjusted to 5 sccm by each mass flow controller. The pressure in the deposition chamber 401 is set to 0.
01 Torr conductance valve 407
The opening of was adjusted. Next, the power of the RF power source 403 is reduced to 0.
The power was set to 40 W / cm ³ and applied to the RF electrode 403.
After that, the power of a μW power supply (not shown) was increased to 0.20 W / cm ³
Is set in the deposition chamber 401 through the dielectric window 413.
W power was introduced to generate glow discharge, the shutter was opened, and the formation of an i-type layer on the n-type layer was started. Using a computer connected to the mass flow controller, SiH ₄ gas in accordance with the flow rate change pattern shown in FIG. 5, C
When the flow rate of the H ₄ gas was changed to produce an i-type layer having a thickness of 300 nm, the shutter was closed, the μW power supply was turned off to stop glow discharge, and the RF power supply 403 was turned off to complete the production of the i-type layer. Valves 2001, 2002, 2004,
Closing 2005, SiH ₄ gas into the deposition chamber 401,
The flow of CH ₄ gas, PH ₃ / H ₂ gas, and B ₂ H ₆ / H ₂ gas was stopped, and H ₂ gas was kept flowing into the deposition chamber 401 for 5 minutes. The inside of the gas pipe was evacuated. The SiH ₄ gas and the CH ₄ gas were mixed at a distance of 0.5 m from the deposition chamber.

Next, in order to form a second p-type layer, the valve 2003 was gradually opened, H ₂ gas was introduced into the deposition chamber 401, and the mass flow controller was adjusted so that the H ₂ gas flow rate became 50 sccm. Adjusted in 2013. The conductance valve is adjusted so that the pressure in the deposition chamber becomes 2.0 Torr, and the heater 405 is set so that the temperature of the substrate 404 becomes 200 ° C. When the substrate temperature is stabilized, the valves 2001, 2002, and 2005 are further turned on. After gradually opening, SiH ₄ gas, CH ₄ gas, and B ₂ H ₆ / H ₂ gas were flowed into the deposition chamber 401. At this time, the flow rate of the SiH ₄ gas is 1 sccm, and the flow rate of the CH ₄ gas is 0.5 scc.
m, H ₂ gas flow rate is _{100sccm, B 2 H 6 / H} 2 gas flow rate were adjusted in each mass flow controllers such that the 100 sccm. The pressure in the deposition chamber 401 is:
The opening of the conductance valve 407 was adjusted to be 0 Torr. The RF power was set to 0.20 W / cm ³ , RF power was introduced, glow discharge was generated, the shutter 415 was opened, and the formation of the second p-type layer on the i-type layer was started. When the second p-type layer having a thickness of 10 nm was formed, the shutter was closed, the RF power was turned off, glow discharge was stopped, and the formation of the second p-type layer was completed. Valve 2001, 2
002 and 2005 are closed and SiH in the deposition chamber 401 is closed.
Stop the inflow of ₄ gas, CH ₄ gas and B ₂ H ₆ / H ₂ gas.
After flowing the H ₂ gas into the deposition chamber 401 for a minute, the valve 2003 is closed, the inside of the deposition chamber 401 and the gas pipe are evacuated, the auxiliary valve 408 is closed, the leak valve 409 is opened, and the deposition chamber 401 is opened. Leaked.

Next, on the second p-type layer, ITO (In ₂ O ₃ + SnO ₂ ) having a thickness of 70 nm was vacuum-deposited as a transparent electrode by a usual vacuum deposition method. Further, a current collecting electrode made of silver (Ag) having a layer thickness of 5 μm was vacuum-deposited on the transparent electrode by an ordinary vacuum vapor deposition method.

Subsequently, a back electrode made of Ag-Ti and having a layer thickness of 3 μm was vacuum-deposited on the back surface of the substrate by a normal vacuum deposition method to complete the manufacture of this solar cell. This solar cell is (S
Table 1 shows the manufacturing conditions of the first p-type layer, the n-type layer, the i-type layer, and the second p-type layer.

<Comparative Example 1> The same as Example 1 except that the SiH ₄ gas flow rate and the CH ₄ gas flow rate were adjusted by the respective mass flow controllers in accordance with the flow rate patterns shown in FIG. 6 when forming the i-type layer. Under the same conditions and the same procedure, the substrate is subjected to hydrogen plasma treatment to form a first p-type layer, an n-type layer, an i-type layer, a second p-type layer, a transparent electrode, a current collecting electrode, and a back electrode on the substrate. Thus, a solar cell was manufactured. This solar cell will be referred to as (SC ratio 1).

< Reference Example 1-1> In forming an i-type layer, the substrate was subjected to hydrogen plasma treatment in the same manner and in the same procedure as in Example 1 except that no PH ₃ / H ₂ gas was allowed to flow. A first p-type layer, an n-type layer, a 1-type layer,
A second p-type layer, a transparent electrode, a current collecting electrode, and a back electrode were formed to produce a solar cell. This solar cell is referred to as (SC
Let's call it 1).

< Reference Example 1-2> In forming an i-type layer, the substrate was subjected to hydrogen plasma treatment by the same method and in the same procedure as in Example 1 except that no B ₂ H ₆ / H ₂ gas was passed. A first p-type layer, an n-type layer, an i-type layer, a second p-type layer, a transparent electrode, a current collecting electrode, and a back electrode were formed on a substrate, to produce a solar cell. This solar cell (SC Ex. 1)
-2).

[0224] In forming a <Example 1-1> i-type layer, except for the μW power to 0.5 W / cm ³ is the same conditions as in Example 1, the same procedure, the substrate is hydrogen plasma treatment Then, a first p-type layer, an n-type layer, an i-type layer, a second p-type layer, a transparent electrode, a current collecting electrode, and a back electrode were formed on a substrate to produce a solar cell. This solar cell is referred to as (SC Ex. 1-3).

<Example 1-2 > When forming an i-type layer, RF power was set to 0.15 W / cm ^3.
A hydrogen plasma treatment was performed on the substrate under the same conditions and in the same procedure as in Example 1 except that the first p-type layer, the n-type layer, the i-type layer, the second p-type layer, An electrode, a current collecting electrode, and a back electrode were formed to produce a solar cell. This solar cell will be referred to as (SC Ex. 114).

<Example 1-3 > In forming the i-type layer, the μW power was set to 0.5 W / cm ³ ,
Example 1 except that the RF power was 0.55 W / cm ³
Under the same conditions and same procedure as above, the substrate is treated with hydrogen plasma,
A first p-type layer, an n-type layer, an i-type layer, a second p-type layer, a transparent electrode, a current collecting electrode, and a back electrode were formed on a substrate, to produce a solar cell. This solar cell is referred to as (SC Ex. 1-5).

<Example 1-4 > In forming the i-type layer, the pressure in the deposition chamber was set to 0.08 Ton.
Except for rr, under the same conditions and the same procedure as in Example 1,
Subjecting the substrate to a hydrogen plasma treatment to form a first p-type layer on the substrate;
an n-type layer, an i-type layer, a second p-type layer, a transparent electrode, a current collecting electrode,
A back electrode was formed to produce a solar cell. This solar cell is referred to as (SC Ex. 1-6).

The fabricated solar cells (SC Ex. 1) and (SC
Ratio 1), (SC Ex 1-1) to (SC Ex 1-6), initial photoelectric conversion efficiency (photoelectromotive power / incident optical power) and durability characteristics were measured.

The measurement of the initial photoelectric conversion efficiency can be obtained by placing the produced solar cell under AM-1.5 (100 mW / cm) light irradiation and measuring the VI characteristics.

As a result of the measurement, (SC ratio 1), (SC actual 1-1) to (SC actual 1)
The initial photoelectric conversion efficiency of 6) was as follows.

(SC ratio 1) 0.42 times (SC actual 1-1) 0.91 times (SC actual 1-2) 0.90 times (SC actual 1-3) 0.63 times (SC actual 1 4) 0.80 times (SC Ex. 1-5) 0.65 times (SC Ex. 1-6) 0.69 times For the measurement of the durability characteristics, the manufactured solar cell was measured at a humidity of 70%,
Installed in a dark place at a temperature of 60 ° C., with an amplitude of 0.3 at 3600 rpm.
After applying a vibration of 1 mm for 24 hours, AM-1.5 (1
(00 mW / cm ² ), due to a decrease in photoelectric conversion efficiency under irradiation (photoelectric conversion efficiency after endurance test / initial photoelectric conversion efficiency). As a result of the measurement, (SC ratio 1), (SC ratio 1-1) to (SC ratio 1)
The decrease in photoelectric conversion efficiency in 6) was as follows.

(SC ratio 1) 0.69 times (SC actual 1-1) 0.90 times (SC actual 1-2) 0.91 times (SC actual 1-3) 0.82 times (SC actual 1 4) 0.80 times (SC Ex. 1-5) 0.87 times (SC Ex. 1-6) 0.83 times Next, a stainless steel base electrode and a barium borosilicate glass (7059 manufactured by Corning Co., Ltd.) substrate were placed. Except that the flow rate of the SiH ₄ gas and the flow rate of the CH ₄ gas were set to the values shown in Table 2, i-type layers of Example 1 were formed on the substrate under the same manufacturing conditions.
A mold layer was formed at 1 μm to prepare a sample for measuring physical properties.
These samples will be referred to as (SP1-1) to (SP1-7). The bandgap (Eg) and composition of the manufactured physical property measurement sample were analyzed, and the relationship between the composition ratio of Si (silicon) atoms and C (carbon) atoms and the bandgap was determined. For the measurement of the band gap, the glass substrate on which the i-type layer was formed was placed on a spectrophotometer (330 manufactured by Hitachi, Ltd.).
And the wavelength dependence of the absorption coefficient of the i-type layer was measured. The band of the i-type layer was measured by the method described on page 109 of the amorphous solar cell (Kyotaka Takahashi and Makoto Konagai, Shokodo Co., Ltd.). The gap was determined.

In the composition analysis, the stainless steel substrate on which the i-type layer was formed was placed on an Auger electron spectrometer (JAM manufactured by JEOL).
P-3), the composition ratio of Si atoms to C atoms was measured. Table 2 and FIG. 7 show the results of band gap and composition analysis.

Next, the fabricated solar cell (SC Ex. 1)
The composition analysis of Si atoms and C atoms in the i-type layer of (SC ratio 1) and (SC actual 1-1) to (SC actual 1-6) in the layer thickness direction was performed in the same manner as the above-described composition analysis. .

From the relationship between the composition ratio of Si atoms and C atoms and the band gap determined by (SP1-1) to (SP1-7), the change in the band gap in the thickness direction of the i-type layer was determined. FIG. 8 shows the result. As can be seen from FIG. 8, (S
In the solar cells of C Ex. 1) and (SC Ex. 1-1) to (SC Ex. 1-6), the position of the minimum value of the band gap is shifted from the center position of the i-type layer toward the p / i interface. , (SC ratio 1), it was found that the position of the minimum value of the band gap was shifted toward the n / i interface from the center position of the i-type layer.

As described above, (SC actual 1), (SC ratio 1), (S
The change of the band gap in the layer thickness direction of C Ex 1-1) to (SC Ex 1-6) depends on the source gas containing Si (in this case, SiH ₄ gas) and the source material containing C, which flow into the deposition chamber. It turned out that it depends on the flow ratio of the gas (in this case, CH ₄ gas).

Next, in the thickness direction of the P atoms and the B atoms in the i-type layers of the solar cells (SC Ex. 1), (SC Ex. 1), (SC Ex. 1-1) to (SC Ex. 1-6), The composition analysis was performed by a secondary ion mass spectrometer (IMS-3F manufactured by CAMECA). As a result of the measurement, P atoms and B atoms were uniformly distributed in the layer thickness direction, and the composition ratio was as follows.

P / (Si + C) B / (Si + C) (SC Ex. 1) ３3 ppm to 10 ppm (SC ratio 1) ３3 ppm to 10 ppm (SC Ex. 1-1) D. -10 ppm (SC Ex 1-2) -3 ppm D. (SC Ex. 1-3) ４4 ppm to 18 ppm (SC Ex. 1-4) ３3 ppm to 10 ppm (SC Ex. 1-5) ４4 ppm to 15 ppm (SC Ex. 1-6) ３3 ppm to 10 ppm D. : Below the detection limit <Example 1-5> What is the μW power and RF power introduced when forming the i-type layer?
The other conditions were the same as in Example 1, except that
Several batteries were made. Figure 9 shows the relationship between μW power and deposition rate.
In this regard, the deposition rate does not depend on the RF power, and the μW power is set to 0.
32W / cm^Three The above is constant, and this electric power
Some SiH_FourGas and CH_FourGas is 100% decomposed
I understood that. AM-1.5 (100 mW / cm^Two)
The initial photoelectric conversion efficiency of the solar cell when irradiated with light is measured.
As a result, the result shown in FIG. 10 was obtained. this
The curve in the figure shows the case where the initial photoelectric conversion efficiency of Example 1 was set to 1.
To show the ratio of initial photoelectric conversion efficiency of each solar cell
The envelope. As can be seen from FIG.
_FourGas and CH_FourΜW power to decompose 100% of gas
(0.32W / cm^Three) Below and the RF power is μW
When the power is larger than the force, the initial photoelectric conversion efficiency is greatly improved.
I knew it was there.

[0239] In the formation of the i-type layer in <Example 1 6> Example 1, the flow rate of the gas introduced into the deposition chamber 401 to change the SiH ₄ gas 50 sccm, a CH ₄ gas to 10 sccm, H ₂ No gas was introduced, and several solar cells were fabricated with various changes in μW power and RF power. Other conditions were the same as in Example 1. Deposition rate and μW
When the relationship between the power and the RF power was examined, the deposition rate did not depend on the RF power as in Example 1-5, and the μW power was 0.1 μM.
It was found to be constant at 18 W / cm ³ or more, and it was found that the SiH ₄ gas and CH ₄ gas as the source gas were decomposed by 100% with this μW power. When the initial photoelectric conversion efficiency of the solar cell when irradiating AM-1.5 light was measured, the result showed the same tendency as FIG. That is, the μW power is 100% of the SiH ₄ gas and the CH ₄ gas.
It was found that the initial photoelectric conversion efficiency was greatly improved when the power was less than the μW power (0.18 W / cm ³ ) and the RF power was larger than the μW power.

[0240] In the formation of the i-type layer in <EXAMPLE 1 7> Example 1, to change the flow rate of the gas introduced into the deposition chamber 401 SiH ₄ gas 200 sccm, CH ₄ gas 50 sccm, a H ₂ gas 500 sccm, Further, several solar cells were manufactured by changing the setting of the heater so that the substrate temperature became 300 ° C. and changing the μW power and the RF power in various ways. Other conditions were the same as in Example 1.

[0241] deposition rate and μW power, where was Chobe the relationship between the RF power, as well as the deposition rate of Example 1 5 does not depend on the RF power, μW power 0.65 W / cm ³ or more It was found that the SiH ₄ gas and the CH ₄ gas, which are the source gases, were decomposed 100% by this electric power.
When the initial photoelectric conversion efficiency of the solar cell when irradiating AM-1.5 light was measured, the result showed the same tendency as FIG. That, .mu.W power the SiH ₄ gas 10
At μW power (0.65 W / cm ³ ) or less for decomposing 0%,
It was also found that when the RF power was larger than the μW power, the initial photoelectric conversion efficiency was greatly improved.

<Example 1-8 > When forming an i-type layer in Example 1, the pressure in the deposition chamber was set at 3 m.
Several solar cells were manufactured by changing various conditions from Torr to 200 mTorr with the other conditions being the same as in Example 1. When the initial photoelectric conversion efficiency of the solar cell when irradiating AM-1.5 light was measured, the result was as shown in FIG. 11, and it was found that the initial photoelectric conversion efficiency was significantly reduced when the pressure was 50 mTorr or more. Was.

As can be seen from the above, according to the embodiment of the present invention.
Solar cell that has been demonstrated to have more excellent characteristics than the solar cell (SC ratio 1).

Example 2 In Example 1, several solar cells were manufactured by changing the position of the minimum value of the band gap (Eg) in the layer thickness direction, the size of the minimum value, and the pattern, and the initial photoelectric conversion was performed. Efficiency and durability were determined in the same manner as in Example 1. At this time, it was the same as Example 1 except for the change pattern of the SiH ₄ gas flow rate and the CH ₄ gas flow rate of the i-type layer. FIG. 12 shows SiH
₄ shows a band diagram for the layer thickness direction of the solar cell when changing the gas flow rate and CH ₄ gas flow rate change pattern. (SC
Actual 2-1) to (SC actual 2-5) are obtained by changing the position of the minimum value of the band gap in the layer thickness direction.
-1) to n / from the p / i interface according to (SC Ex. 2-5)
It is changed toward the i-interface. (SC Actual 2-
6) and (SC Ex 2-7) are obtained by changing the minimum value of the band gap of (SC Ex 2-1). (SC Actual 2-
8) to (SC Ex. 2-10) are obtained by changing the band pattern. Table 3 shows the results of examining the initial photoelectric conversion efficiency and durability characteristics of these manufactured solar cells ((SC
Actual 2-1) was used as a reference). As can be seen from these results, the band gap of the i-type layer smoothly changes in the layer thickness direction regardless of the size and the change pattern of the minimum value of the band gap, and the position of the minimum value of the band gap is changed to the i-type layer. It has been found that the solar cell of the present invention, which is shifted in the direction of the p / i interface from the central position of the above, is superior.

Example 3 In Example 1, several solar cells were produced in which the concentration and type of the valence electron controlling agent in the i-type layer were changed, and the initial photoelectric conversion efficiency and the durability were the same as in Example 1. In a particular way. At this time, the procedure was the same as in Example 1 except that the concentration and type of the valence electron controlling agent in the i-type layer were changed.

<Example 3-1> Gas (B) for a valence electron controlling agent serving as an acceptor for the i-type layer
A solar cell (SC Ex. 3-1) in which the flow rate of ₂ H ₆ / H ₂ gas) was reduced to 1/5 and the total H ₂ flow rate was the same as in Example 1 was produced. It was found that it had better initial photoelectric conversion efficiency and durability than the conventional solar cell (SC ratio 1).

<Example 3-2> Gas (B) for a valence electron controlling agent serving as an acceptor for an i-type layer
A solar cell (SC Ex. 3-2) with the flow rate of ₂ H ₆ / H ₂ gas) increased by 5 times and the total H ₂ flow rate as in Example 1 was fabricated. Solar cell (S
It was found that the C ratio 1) also had better initial photoelectric conversion efficiency and durability.

<Example 3-3> Gas for valence electron controlling agent (PH ₃ /
A solar cell (SC Ex. 3-3) having the same H ₂ flow rate as that of Example 1 was manufactured by reducing the flow rate of H ₂ gas to 倍 times. It was found that it had better initial photoelectric conversion efficiency and durability than (SC ratio 1).

<Example 3-4> Gas for valence electron controlling agent (PH ₃ /
A solar cell (SC Ex. 3-4) with a H ₂ gas) flow rate increased by 5 times and the total H ₂ flow rate made the same as in Example 1 was produced, as in (SC Ex. 1). It was found that it had better initial photoelectric conversion efficiency and durability than SC ratio 1).

<Example 3-5> Instead of B ₂ H ₆ / H ₂ gas as a gas for a valence electron controlling agent serving as an acceptor of an i-type layer, trimethyl aluminum (Al (CH _{3 3} , abbreviated as TMA). At this time, the same method and procedure as in Example 1 are used, except that TMA (purity 99.99%) sealed in a liquid cylinder is gasified by bubbling with hydrogen gas and introduced into the deposition chamber 401. A solar cell (SC Ex. 3-5) was produced. At this time, TMA /
The flow rate of the H ₂ gas was set to 10 sccm.

The fabricated solar cell (SC Ex. 3-5) is (S
Similar to C Ex 1), it was found to have better initial photoelectric conversion efficiency and durability than a conventional solar cell (SC ratio 1).

<Example 3-6> PH as a gas for a valence electron controlling agent serving as a donor of an i-type layer
A solar cell using hydrogen sulfide (H ₂ S) gas instead of ₃ / H ₂ gas was produced. The NH ₃ / H ₂ gas cylinder of Example 1 was replaced with an H ₂ S gas (purity: 99.999%, hereinafter abbreviated as “H ₂ S / H ₂ ”) diluted to 100 ppm with hydrogen (H ₂ ). A solar cell (SC Ex. 3-6) was manufactured using the same method and procedure as in Example 1. At this time, the flow rate of the H ₂ S / H ₂ gas was set at 1 sccm, and the other conditions were the same as in Example 1.

The manufactured solar cell (SC Ex. 3-6) is (S
Similar to C Ex 1), it was found to have better initial photoelectric conversion efficiency and durability than a conventional solar cell (SC ratio 1).

Example 4 The solar cell of FIG. 1 was manufactured using a polycrystalline silicon substrate manufactured by a p-type casting method. The substrate is subjected to a hydrogen plasma treatment, and a first n-type layer, a p-type layer, i
A mold layer and a second n-type layer are sequentially formed, and Table 4 shows the formation conditions. When forming the i-type layer, the flow rate of the SiH ₄ gas and the flow rate of the CH ₄ gas were changed as shown in the pattern of FIG. 6 so that the minimum value of the band gap came near the p / i interface. The layers other than the substrate and the semiconductor layer were manufactured under the same conditions and the same method as in Example 1. It was found that the produced solar cell (SC Ex. 4) had better initial photoelectric conversion efficiency and durability than the conventional solar cell (SC ratio 1), similarly to (SC Ex. 1).

Example 5 A solar cell having a band gap maximum value of the i-type layer near the p / i interface and a thickness in that region of 20 nm was manufactured. FIG. 13A shows a flow rate change pattern of the i-type layer. i
It was manufactured using the same conditions and the same method as in Example 1 except that the flow rate change pattern of the mold layer was changed.

Next, the composition of the solar cell was analyzed in the same manner as in Example 1, and the change in the band gap in the thickness direction of the i-type layer was examined based on FIG. The result was as follows.

It was found that the manufactured solar cell (SC Ex. 5) had better initial photoelectric conversion efficiency and durability than the conventional solar cell (SC Ex. 1), similarly to (SC Ex. 1).

Comparative Example 5 There was a region having the maximum value of the band gap near the p / i interface of the i-type layer, and several solar cells were manufactured with various thicknesses of the region. Example 5 except for the thickness of the region
It was produced under the same conditions and using the same method. When the initial photoelectric conversion efficiency and the durability characteristics of the manufactured solar cell were measured, when the thickness of the region was 1 nm or more and 30 nm or less, the initial photoelectric conversion efficiency and the better even more than the solar cell of Example 1 (SC Ex. 1). Durability characteristics were obtained.

Example 6 A solar cell having a maximum value of the band gap of the i-type layer near the n / i interface and a thickness of the region of 15 nm was manufactured. FIG. 13C shows a flow rate change pattern of the i-type layer. i
It was manufactured using the same conditions and the same method as in Example 1 except that the flow rate change pattern of the mold layer was changed.

Next, the composition of the solar cell was analyzed in the same manner as in Example 1, and the change in the band gap in the thickness direction of the i-type layer was examined based on FIG. The result was as follows. The fabricated solar cell (SC Ex. 6) is (SC
As in the case of Example 1), it was found that the solar cell had better initial photoelectric conversion efficiency and durability than the conventional solar cell (SC ratio 1).

Comparative Example 6 There was a region having the maximum band gap near the n / i interface of the i-type layer, and several solar cells were manufactured with various thicknesses of the region. Example 6 except for the thickness of the region
It was produced under the same conditions and using the same method. When the initial photoelectric conversion efficiency and durability characteristics of the manufactured solar cell were measured, the initial photoelectric conversion efficiency and durability were more excellent than the solar cell of Example 1 (SC Ex. 1) when the thickness of the region was 1 nm or more and 30 nm or less. Characteristics were obtained.

Example 7 A solar cell in which a valence electron controlling agent was distributed in an i-type layer was manufactured. FIG. 14A shows a change pattern of the flow rates of the PH ₃ / H ₂ gas and the B ₂ H ₆ / H ₂ gas. At the time of fabrication, PH ₃ / H ₂
Except for changing the flow rates of the gas and the B ₂ H ₆ / H ₂ gas, the same conditions, the same method, and the same procedure as in Example 1 were used. It was found that the manufactured solar cell (SC Ex. 7) had better initial photoelectric conversion efficiency and durability than the conventional solar cell (SC Ex. 1), similarly to (SC Ex. 1). Also, i
When the change in the layer thickness direction of the P atoms and the B atoms contained in the mold layer was measured using a secondary ion mass spectrometer (SIMS), as shown in FIG. At the position, it was found that the content of P atoms and B atoms was minimized.

Example 8 A solar cell having an i-type layer containing oxygen atoms was manufactured. When forming the i-type layer, in addition to the gas flowing in Example 1,
The same conditions, the same method, and the same procedure as in Example 1 were used, except that O ₂ / He gas was introduced into the deposition chamber 401 at 10 sccm. The fabricated solar cell (SC Ex. 8) is (SC Ex. 1)
Similarly to the above, it was found that the solar cell had better initial photoelectric conversion efficiency and durability than the conventional solar cell (SC ratio 1).

Also, the content of oxygen atoms in the i-type layer is determined by SI
As a result of preparation by MS, it was almost uniformly contained and 2 × 10 ¹⁹
(Pieces / cm ³ ).

Example 9 A silicon solar cell having an i-type layer containing nitrogen atoms was manufactured. When forming the i-type layer, the same conditions, the same method, and the same procedure as in Example 1 are used except that NH ₃ / H ₂ gas is introduced into the deposition chamber 401 at 5 sccm in addition to the gas flowing in Example 1. Was. It was found that the produced solar cell (SC Ex. 9) had better initial photoelectric conversion efficiency and durability than the conventional solar cell (SC Ex. 1), similarly to (SC Ex. 1). In addition, the content of nitrogen atoms in the i-type layer was determined by SIM
When adjusted with S, it was almost uniformly contained and 3 × 10
¹⁷ (pieces / cm ³ ).

Example 10 A solar cell having an i-type layer containing oxygen atoms and nitrogen atoms was manufactured. When forming the i-type layer, in addition to the gas flowing in Example 1, O ₂ / He gas is 5 sccm and NH ₃ / H ₂
The same conditions, the same method, and the same procedure as in Example 1 were used except that the gas was introduced into the deposition chamber 401 at 5 sccm. The manufactured solar cell (SC Ex. 10) was found to have better initial photoelectric conversion efficiency and durability than the conventional solar cell (SC ratio 1), similarly to (SC Ex. 1). Further, the contents of oxygen atoms and nitrogen atoms in the i-type layer were determined by SIMS.
As a result, it was almost uniformly contained.
It was found to be 10 ¹⁹ (pieces / cm ³ ) and 3 × 10 ¹⁷ (pieces / cm ³ ).

Example 11 A solar cell was manufactured in which the hydrogen content of the i-type layer was changed corresponding to the silicon content. O ₂ / He gas cylinder S
Replace with iF ₄ gas (99.999% purity) cylinder
When forming the mold layer, the flow rates of the SiH ₄ gas, CH ₄ gas, and SiF ₄ gas were changed according to the flow pattern shown in FIG. The change in the band gap in the layer thickness direction of this solar cell (SC Ex. 11) was determined in the same manner as in Example 1. It is shown in FIG.

Further, the content of hydrogen atoms and silicon atoms was analyzed in the thickness direction using a secondary ion mass spectrometer. As a result, as shown in FIG. 15C, it was found that the hydrogen atom content had a distribution in the layer thickness direction corresponding to the silicon atom content. This solar cell (SC actual 1)
When the initial photoelectric conversion efficiency and the durability characteristics of 1) were obtained, a conventional solar cell (SC ratio 1) was obtained as in the solar cell of Example 1.
It was found to have even better initial photoelectric conversion efficiency and durability characteristics.

Example 12 When forming the semiconductor layer of the solar cell shown in FIG. 1 by the manufacturing apparatus using the microwave plasma CVD method shown in FIG. 4, a silicon atom-containing gas (SiH ₄ gas) and a carbon atom-containing gas were used. A solar cell (SC Ex. 12) was produced in the same manner and in the same procedure as in Example 1 except that the gas (CH ₄ gas) was mixed at a distance of 4 m from the deposition chamber. The fabricated solar cell (SC
Example 12) was found to have better initial photoelectric conversion efficiency and durability than (SC ratio 1).

Example 13 When a first p-type layer was formed by a gas diffusion method and an i-type layer was formed, a positive DC bias was applied to the RF electrode 410,
A solar cell in which power, DC bias, and μW power were changed was manufactured.

When forming the first p-type layer, a NH ₃ / H ₂ gas cylinder was diluted with hydrogen to 10% BBr ₃ gas (purity 99.999%, hereinafter abbreviated as “BBr ₃ / H ₂ gas”). ) Change to a cylinder, substrate temperature 900 ° C, BBr ₃ / H ₂
Under a diffusion condition of a gas flow rate of 500 sccm and an internal pressure of 30 Torr, when the junction depth becomes about 300 nm, BBr
The introduction of ₃ / H ₂ gas was stopped, and an n-type layer was formed under the same conditions as in Example 1. Next, when forming the i-type layer, the RF electrode 410
Was applied with a positive DC bias, and the RF power, the DC bias, and the μW power were changed as shown in FIG. 16 to produce a solar cell.

The manufactured solar cell (SC Ex. 13) is (SC
As in the case of Example 1), it was found that the solar cell had better initial photoelectric conversion efficiency and durability than the conventional solar cell (SC ratio 1).

Example 14 The triple solar cell shown in FIG. 17 was manufactured using the manufacturing apparatus shown in FIG. 4 using the microwave plasma CVD method of the present invention.

An n-type polycrystalline silicon substrate manufactured by a casting method was used. 50 × 50mm
One side of the ^second substrate temperature 100 ° C. of NaOH (H ₂ O with 1%
) For 5 minutes and washed with pure water. Na
When the surface immersed in OH was observed with a scanning electron microscope (SEM), irregularities having a pyramid structure were formed on the surface, and the substrate was textured (Texture).
d) It was found that it was done. Next, the substrate was ultrasonically washed with acetone and isopropanol, further washed with pure water, and dried with warm air.

In the same procedure and in the same manner as in Example 1, the substrate was subjected to hydrogen plasma treatment, a first p-type layer was formed on the textured surface of the substrate, and the first n-type layer and the first i-type layer, second p-type layer, second n-type layer, second i-type layer, third
Were sequentially formed. When forming the second i-type layer,
The SiH ₄ gas flow rate and CH ₄ gas flow rate were changed according to the flow rate change pattern as shown in FIG.

Next, on the third p-type layer, as in Example 1, a transparent electrode of ITO (In ₂ O ₃ +
SnO ₂ ) and silver (Ag) having a layer thickness of 5 μm as a current collecting electrode were vacuum-deposited. Subsequently, as in Example 1, a 3 μm-thick back electrode made of Ag—Ti was vacuum-deposited on the back surface of the substrate.

The fabrication of the triple solar cell using the microwave plasma CVD method has been completed. This solar cell will be referred to as (SC Ex. 14). Table 5 shows the manufacturing conditions of each semiconductor layer.

<Comparative Example 14> When forming the second i-type layer of FIG. 17, the same as Example 14 except that the flow rate of the SiH ₄ gas and the flow rate of the CH ₄ gas were changed according to the flow rate change pattern of FIG. A triple-type solar cell was produced by the same method and procedure. This solar cell (SC
Ratio 14).

The initial photoelectric conversion efficiency and durability characteristics of these fabricated triple solar cells were measured in the same manner as in Example 1. (SC Ex. 14) was higher than that of the conventional triple type solar cell (SC ratio: 14). Was found to have better initial photoelectric conversion efficiency and durability.

Example 15 The solar cell of Example 1 was manufactured using the manufacturing apparatus of FIG. 4 using the microwave plasma CVD method of the present invention, and was modularized and applied to a power generation system.

Under the same conditions, the same method, and the same procedure as in Example 1, 65 solar cells (SC Ex. 1) of 50 × 50 mm ² were manufactured. EVA on 5.0mm thick aluminum plate
An adhesive sheet made of (ethylene vinyl acetate) was placed thereon, a nylon sheet was placed thereon, and the solar cells produced were further arranged thereon, and serialization and parallelization were performed. An EVA adhesive sheet was placed thereon, and a fluororesin sheet was further placed thereon, followed by vacuum lamination to form a module. The initial photoelectric conversion efficiency of the manufactured module was measured in the same manner as in Example 1. The module was connected to the circuit showing the power generation system of FIG. 18, and an external light that was lit at night was used for the load. The entire system was powered by the battery and the power of the module, and the module was installed at an angle that could best collect sunlight. After one year, the photoelectric conversion efficiency was measured, and the light deterioration rate (photoelectric conversion efficiency after one year / initial photoelectric conversion efficiency) was obtained. This module is called (MJ Actual 15).

<Comparative Example 15> 65 conventional solar cells (SC ratio 1) were manufactured, and
It was modularized in the same manner as 5. This module (MJ
We will call it ratio 15). Under the same conditions, the same method, and the same procedure as in Example 15, the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after one year had elapsed were measured, and the light deterioration rate was obtained.

As a result, the light degradation rate of (MJ ratio 15) was as follows with respect to (MJ actual 15).

Module Light Deterioration Ratio MJ Actual 15 1.00 MJ Ratio 15 0.92 From the above results, the solar cell module according to the embodiment of the present invention has more excellent light deterioration characteristics than the conventional solar cell module. It was found to have. << Reference Example 2 >> In this example , an n-type polycrystalline silicon substrate manufactured by a casting method was used to manufacture the solar cell shown in FIG. 1 having a second p-type layer in a laminated structure.

First, a substrate of 50 × 50 mm ² was subjected to HF and H
It was immersed in an aqueous solution of NO ₃ (diluted to 10% with H ₂ O) for several seconds and washed with pure water. Next, the substrate was ultrasonically washed with acetone and isopropanol, further washed with pure water, and dried with warm air. Next, a semiconductor layer was formed on the substrate by a manufacturing apparatus using a glow discharge decomposition method including a source gas supply apparatus 2000 and a deposition apparatus 400 shown in FIG. The manufacturing procedure is described below.

After the preparation for film formation was completed in the same manner as in Example 1, the substrate was subjected to hydrogen plasma treatment, and a first p-type layer, an n-type layer, an i-type layer, and a second A p-type layer was formed.

First, in order to perform the hydrogen plasma treatment, the valve 2003 was gradually opened, H ₂ gas was introduced into the deposition chamber 401, and the mass flow controller 2013 adjusted the H ₂ gas flow rate to 500 sccm. The conductance valve is adjusted while watching the vacuum gauge 402 so that the pressure in the deposition chamber becomes 2.0 Torr, and the heater 405 is set so that the temperature of the substrate 404 becomes 500 ° C. (ΜW) The power supply was set to 0.20 W / cm ³ and μW power was introduced.
Glow discharge was generated, shutter 415 was opened, and hydrogen plasma treatment was started. After 10 minutes, close the shutter, turn off the μW power supply, stop glow discharge,
The hydrogen plasma treatment was completed. After continuously flowing the H ₂ gas into the deposition chamber 401 for 5 minutes, the valve 2003 was closed, and the inside of the deposition chamber 401 and the inside of the gas pipe were evacuated.

Next, to form the first p-type layer, the valve 2003 was gradually opened, H ₂ gas was introduced into the deposition chamber 401, and the mass flow controller was adjusted so that the H ₂ gas flow rate became 50 sccm. Adjusted in 2013. The conductance valve is adjusted while watching the vacuum gauge 402 so that the pressure in the deposition chamber becomes 2.0 Torr, and the heater 405 is set so that the temperature of the substrate 404 becomes 350 ° C. 200
1, 2005, gradually open, SiH ₄ gas, B ₂ H ₆ /
H ₂ gas was introduced into the deposition chamber 401. At this time, Si
H ₄ gas flow rate is 5 sccm, H ₂ gas flow rate is 100 sccc
m and each of the mass flow controllers were adjusted so that the flow rate of the B ₂ H ₆ / H ₂ gas was 500 sccm. The opening of the conductance valve 407 was adjusted while watching the vacuum gauge 402 so that the pressure in the deposition chamber 401 became 2.0 Torr. Set the RF power to 0.20 W / cm ³ ,
Introduce F power to generate glow discharge, shutter 4
15 was opened, and the formation of the first p-type layer on the substrate was started.
When the first p-type layer having a thickness of 100 nm was formed, the shutter was closed, the RF power was turned off, glow discharge was stopped, and the formation of the first p-type layer was completed. Valve 2001, 2005
Is closed, SiH ₄ gas and B ₂ H ₆ into the deposition chamber 401 are closed. /
Stopping the flow of H ₂ gas for 5 minutes, after which continued to flow H ₂ gas into the deposition chamber 401, closing the valve 2003, the deposition chamber 4
The inside of 01 and the inside of the gas pipe were evacuated.

To form the n-type layer, the auxiliary valve 40
8. Open the valve 2003 gradually, introduce H ₂ gas into the deposition chamber 401 through the gas introduction pipe 411, set the mass flow controller 2013 so that the H ₂ gas flow rate becomes 50 sccm, and set the pressure in the deposition chamber to 1 .0Tor
r with the conductance valve so that the substrate 4
Heater 405 so that the temperature of 04 becomes 350 ° C.
It was set. When the substrate temperature was stabilized, the valves 2001 and 2004 were gradually opened, and SiH ₄ gas and
PH ₃ / H ₂ gas was flowed into the deposition chamber 401. At this time, the flow rate of the SiH ₄ gas was ₂ sccm, and the flow rate of the H ₂ gas was 10 sccm.
Each mass flow controller was adjusted so that the flow rate of the PH ₃ / H ₂ gas was 200 sccm at 0 sccm.
The opening of the conductance valve 407 was adjusted so that the pressure in the deposition chamber 401 became 1.0 Torr. After confirming that the shutter 415 is closed, the power of the RF power supply is set to 0.01 W / cm ³ , RF power is introduced to the RF electrode 410, a glow discharge is generated, the shutter is opened, and the first shutter is opened. The production of the n-type layer was started on the p-type layer. When the n-type layer having a thickness of 30 nm was produced, the shutter was closed, the RF power was turned off, the glow discharge was stopped, and the formation of the n-type layer was completed. The valves 2001 and 2004 are closed to stop the flow of the SiH ₄ gas and the PH ₃ / H ₂ gas into the deposition chamber 401, and the H ₂ gas is continuously flown into the deposition chamber 401 for 5 minutes, and then the outflow valve 2003 is closed. The inside of the deposition chamber 401 and the inside of the gas pipe were evacuated.

Next, in order to manufacture an i-type layer, the valve 20 was used.
03 was gradually opened, H ₂ gas was introduced into the deposition chamber 401, and the mass flow controller 2013 adjusted the H ₂ gas flow rate to 300 sccm. The conductance valve is adjusted so that the pressure in the deposition chamber becomes 0.01 Torr, and the heater 405 is set so that the temperature of the substrate 404 becomes 350 ° C. When the substrate temperature is stabilized, the valves 2001 and 2002 are gradually opened. And S
iH ₄ gas and CH ₄ gas were caused to flow into the deposition chamber 401.
At this time, the respective mass flow controllers were adjusted so that the flow rate of the SiH ₄ gas was 100 sccm, the flow rate of the CH ₄ gas was 30 sccm, and the flow rate of the H ₂ gas was 300 sccm.
The opening of the conductance valve 407 was adjusted so that the pressure in the deposition chamber 401 was 0.01 Torr. Next, the power of the RF power supply 403 was set to 0.40 W / cm ³ and applied to the RF electrode 403. Thereafter, μW (not shown)
Set the power of the power supply to 0.20 W / cm ³ and set the dielectric window 4
A power of μW was introduced into the deposition chamber 401 through 13 to generate glow discharge, a shutter was opened, and the formation of an i-type layer on the n-type layer was started. Using a computer connected to a mass flow controller, the flow rates of SiH ₄ gas and CH ₄ gas were changed according to the flow rate change pattern shown in FIG. 5, and a 300 nm-thick i-type layer was produced. To stop glow discharge,
The F power source 403 was turned off, and the fabrication of the i-type layer was completed. Valve 2
001 and 2002 are closed and the SiH
_4. The flow of CH ₄ gas was stopped, and H ₂ gas was allowed to flow into the deposition chamber 401 for 5 minutes. After that, the valve 2003 was closed, and the inside of the deposition chamber 401 and the inside of the gas pipe were evacuated.

Next, in order to form the second p-type layer, the valve 2003 is gradually opened, H ₂ gas is introduced into the deposition chamber 401, and the mass flow controller is adjusted so that the H ₂ gas flow rate becomes 300 sccm. Adjusted in 2013. The conductance valve is adjusted so that the pressure in the deposition chamber becomes 0.02 Torr, and the heater 405 is set so that the temperature of the substrate 404 becomes 200 ° C. When the substrate temperature becomes stable, the valves 2001, 2002, and 200
5 was gradually opened, and SiH ₄ gas, CH ₄ gas, H ₂ gas, and B ₂ H ₆ / H ₂ gas were flowed into the deposition chamber 401.
At this time, the flow rate of the SiH ₄ gas was 10 sccm, the flow rate of the CH ₄ gas was 5 sccm, the flow rate of the H ₂ gas was 300 sccm, and B ₂ H
Each mass flow controller adjusted the flow rate of ₆ / H ₂ gas to 10 sccm. The opening of the conductance valve 407 was adjusted so that the pressure in the deposition chamber 401 was 0.02 Torr. 0.30 μW power supply
W / cm ³ and the deposition chamber 4 through the dielectric window 413.
01, a glow discharge was generated to generate glow discharge, the shutter 415 was opened, and the formation of a lightly doped layer (this layer is referred to as an A layer) on the i-type layer was started. When the A layer having a thickness of about 3 nm was formed, the shutter was closed, the μW power was turned off, and the glow discharge was stopped. Valve 2001, 200
2. Closing 2005, stop the flow of SiH ₄ gas, CH ₄ gas, and B ₂ H ₆ / H ₂ gas into the deposition chamber 401, and continue flowing H ₂ gas into the deposition chamber 401 for 5 minutes. Then, the valve 2003 was closed, and the inside of the deposition chamber 401 and the inside of the gas pipe were evacuated.

Next, the valve 2005 is gradually opened to allow the B ₂ H ₆ / H ₂ gas to flow into the deposition chamber 401 so that the flow rate becomes 10%.
It was adjusted with a mass flow controller so as to be 00 sccm. The conductance valve is adjusted so that the pressure in the deposition chamber becomes 0.02 Torr, the power of the μW power supply is set to 0.20 W / cm ³ , the μW power is introduced into the deposition chamber 401 through the dielectric window 413, and the glow is applied. Discharge is generated, shutter 415 is opened, and boron (B) is formed on layer A.
(This layer is referred to as layer B). After 6 seconds, close the shutter, turn off the μW power supply,
Glow discharge was stopped. The valve 2005 is closed to stop the flow of the B ₂ H ₆ / H ₂ gas into the deposition chamber 401, for 5 minutes.
After flowing H ₂ gas into the deposition chamber 401 continuously, the valve 2
003 was closed, and the inside of the deposition chamber 401 and the inside of the gas pipe were evacuated.

Next, the A layer was formed on the B layer by the same method, the same procedure, and the same conditions as those described above. Further, a B layer was formed thereon by the same method, the same procedure, and the same conditions as those described above. On top of that, the same method, the same procedure,
The A layer was formed under the same conditions, and the formation of the second p-type layer having a thickness of about 10 nm was completed.

The auxiliary valve 408 is closed and the leak valve 4
09 was opened, and the deposition chamber 401 was leaked.

Next, 70 nm thick ITO (In ₂ O ₃ + SnO ₂ ) as a transparent electrode and 5 μm thick silver (Ag) as a current collecting electrode were vacuum-deposited on the second p-type layer. Subsequently, a back electrode having a layer thickness of 3 μm made of Ag-Ti was vacuum-deposited on the back surface of the substrate to complete the manufacture of the solar cell. This solar cell will be referred to as (SC Ex. 16), a first p-type layer,
Table 6 shows the conditions for forming the n-type layer, the i-type layer, and the second p-type layer.

<Comparative Example 16> Same as Reference Example 2 except that the SiH ₄ gas flow rate and CH ₄ gas flow rate were adjusted by the respective mass flow controllers according to the flow rate patterns shown in FIG. 6 when forming the i-type layer. A solar cell was manufactured under the same procedure under the same conditions. This solar cell will be referred to as (SC ratio 16).

The fabricated solar cells (SC Ex 16) and (S
The initial photoelectric conversion efficiency (photovoltaic power / incident light power) and durability characteristics of C ratio 16) were measured.

As a result of the measurement, the initial photoelectric conversion efficiency of (SC ratio 16) with respect to the solar cell of (SC Ex 16) was as follows.

(SC ratio 16) The decrease in photoelectric conversion efficiency of (SC ratio 16) with respect to the solar cell of 0.92 times (SC actual 16) was as follows.

(SC ratio 16) 0.92 times Next, the manufactured solar cell (SC actual 16), (SC ratio 1
6) The composition analysis in the layer thickness direction of Si atoms and C atoms in the i-type layer is performed in the same manner as in the above-described composition analysis. When the change in the band gap in the layer thickness direction was obtained, the same result as that in FIG. 8 was obtained.

Next, a second p-type layer having a laminated structure was formed on a polycrystalline silicon substrate, and a cross-sectional TEM (transmission electron microscope) image thereof was observed. A second p-type layer was formed on a substrate by the same method and procedure as in Reference Example 2 except that the deposition time of the B layer was changed to 12 seconds. The prepared sample was cut in the cross-sectional direction, and the state of lamination of the A layer and the B layer in the second p-type layer was observed. As shown in FIG. 19, the B layer having a layer thickness of about 1 nm and the layer thickness of about 3 nm It was found that the layer A was alternately laminated.

As can be seen from the above , ( SC Actual 16)
It has been demonstrated that the solar cell has more excellent characteristics than a conventional solar cell (SC ratio 16).

Reference Example 3 In Reference Example 2 , several solar cells were manufactured by changing the position of the minimum value of the band gap (Eg) in the layer thickness direction, the size of the minimum value, and the pattern, and the initial photoelectric conversion was performed. Efficiency and durability were examined in the same manner as in Reference Example 2 . At this time, it was the same as Reference Example 2 except for the change pattern of the SiH ₄ gas flow rate and CH ₄ gas flow rate of the i-type layer. In this example , Si
By changing the change pattern of H ₄ gas flow rate and CH ₄ gas flow rate,
A solar cell having the band diagram shown in FIG. 12 was manufactured.

Table 7 shows the results obtained by examining the initial photoelectric conversion efficiency and the durability of these solar cells ((SC
Based on the value of the actual 17-1)). As can be seen from these results, the band gap of the i-type layer smoothly changes in the layer thickness direction regardless of the size and the change pattern of the minimum value of the band gap, and the position of the minimum value of the band gap is i
It was found that towards the center p / i interface direction to offset though that thickness <br/> solar cell from the position of the mold layer is superior.

Reference Example 4 A solar cell in which the B layer was formed by a mercury-sensitized CVD method was manufactured. A quartz glass window having a diameter of 100 mm and a thickness of 10 mm and a low-pressure mercury lamp were attached to the manufacturing apparatus shown in FIG. 4, and light from the low-pressure mercury lamp was made to enter the deposition chamber through the quartz glass window. In addition, a shutter (window shutter) for covering the quartz glass window was installed inside the deposition chamber so that the deposits did not adhere. Further, mercury (purity: 99.48) was introduced into a liquid cylinder (2048 in FIG. 4) having valves at the inlet and outlet.
999%).

This cylinder was mass-flowed with the valve 2005.
Installed between controllers 2015, B_TwoH6 / H_Two
By bubbling with gas, B_TwoH₆/
H_Two Mercury vaporized with gas can be introduced
Was. When forming the B layer, B_TwoH₆/ H_TwoGas flow rate 10
00 sccm, flow into the deposition chamber, and set the pressure to 1.0 To
rr, open the shutter 415 in advance,
Turn on the silver lamp, open the window shutter for 60 seconds,
Except for forming the layer B on the layer,Reference example 2Same conditions as
The solar cell of FIG. 1 was produced by the same method and the same procedure. Production
Solar cell (SC Ex 18) is similar to (SC Ex 16)
Better initial than conventional solar cells (SC ratio 16)
It was found to have photoelectric conversion efficiency and durability characteristics.

Reference Example 5 A solar cell using a p-type polycrystalline silicon substrate was manufactured. A first n-type layer, a p-type layer, an i-type layer, a second n-type layer
The mold layers were sequentially formed, and the forming conditions are shown in Table 8. When forming the i-type layer, the flow rate of the SiH ₄ gas and the flow rate of the CH ₄ gas were changed as shown in the pattern of FIG. 6 so that the minimum value of the band gap came near the p / i interface. Further, the second n-type layer had a laminated structure as in Reference Example 2 . Layers other than the substrate and the semiconductor layer were manufactured using the same conditions and the same method as in Reference Example 2 . The manufactured solar cell (SC actual 19) is (SC actual 1)
As in 6), it was found that the solar cell had better initial photoelectric conversion efficiency and better durability than the conventional solar cell (SC ratio 16).

Reference Example 6 A solar cell having a maximum value of the band gap of the i-type layer near the p / i interface and a thickness of the region of 20 nm was manufactured. Except for the flow rate change pattern of the i-type layer shown in FIG. 13A, it was manufactured using the same conditions and the same method as in Reference Example 2 . Next, the composition analysis of the solar cell was performed in the same manner as in Reference Example 2, and the change in the band gap in the layer thickness direction of the i-type layer was examined based on FIG. The result was. The manufactured solar cell (SC actual 20) is (SC actual 16)
Similarly to the above, it was found that the solar cell had better initial photoelectric conversion efficiency and durability than the conventional solar cell (SC ratio 16).

< Comparative Example 20 > There was a region having the maximum value of the band gap near the p / i interface of the i-type layer, and several solar cells were manufactured in which the thickness of the region was variously changed. Reference Example 6 except for the thickness of the region
It was produced under the same conditions and using the same method. When the initial photoelectric conversion efficiency and durability characteristics of the manufactured solar cell were measured, when the thickness of the region was 1 nm or more and 30 nm or less, the reference was obtained.
Even better initial photoelectric conversion efficiency and durability were obtained than the solar cell of Example 2 (SC Ex 16).

Reference Example 7 A solar cell having a maximum value of the band gap of the i-type layer near the n / i interface and having a thickness of 15 nm in that region was manufactured. Except the flow rate change pattern of the i-type layer shown in FIG. 13-3 were produced under similar conditions, the same method as in Reference Example 2. Next, the composition analysis of the solar cell was performed in the same manner as in Reference Example 2, and the change in the band gap in the layer thickness direction of the i-type layer was examined based on FIG. The result was. The fabricated solar cell (SC Ex 21) is (SC Ex 16)
Similarly to the above, it was found that the solar cell had better initial photoelectric conversion efficiency and durability than the conventional solar cell (SC ratio 16).

Comparative Example 21 There was a region having the maximum value of the band gap near the n / i interface of the i-type layer, and several solar cells were manufactured with various thicknesses of the region. Reference Example 7 except for the thickness of the region
It was produced under the same conditions and using the same method. When the initial photoelectric conversion efficiency and the durability of the manufactured solar cell were measured, the reference example was obtained when the thickness of the region was 1 nm or more and 30 nm or less.
The better initial photoelectric conversion efficiency and durability were obtained than the solar cell No. 2 (SC Ex. 16).

Reference Example 8 In forming the second p-type layer, triethyl boron (B (C ₂ H ₅ ) ₃ , abbreviated as TEB) is used instead of B ₂ H ₆ / H ₂ gas. A solar cell was manufactured.

Liquid TEB (purity 99.9) at normal temperature and pressure
9%) and a liquid cylinder with a valve at the inlet and outlet (Fig. 4
2048). The bomb was attached to the raw material gas supply device and bubbled with H ₂ gas, so that TEB vaporized together with H ₂ gas could be introduced into the deposition chamber.

[0314] Reference example except that the flow rate of TEB / H ₂ gas was 10 sccm when the layer A was formed,
The A layer was formed on the i-type layer by the same procedure and under the same conditions as in 2, and the deposition chamber was evacuated after flowing H ₂ gas into the deposition chamber for 5 minutes.

[0315] When forming the B layer, except for flowing the flow rate of the TEB / H ₂ gas 1000 sccm, the deposition chamber ginseng
A layer B is formed on the i-type layer under the same conditions and procedures as those of the second embodiment, and
After the H ₂ gas was allowed to flow into the deposition chamber for minutes, the deposition chamber was evacuated.

Next, an A layer was formed on the B layer, and H _{2 was applied for} 5 minutes.
After flowing the gas into the deposition chamber, the deposition chamber was evacuated.

Next, a layer B was formed on the layer A and H _{2 was applied for} 5 minutes.
After flowing the gas into the deposition chamber, the deposition chamber was evacuated. Next, the layer A was formed on the layer B, and after flowing H ₂ gas into the deposition chamber for 5 minutes, the deposition chamber was evacuated.

[0318] other than the p-type layer under the same conditions as in Reference Example 2, the method,
Produced by the procedure. The produced solar cell (SC Ex. 22) is the same as the conventional solar cell (SC Ex. 16) as in (SC Ex. 16).
It was found to have even better initial photoelectric conversion efficiency and durability characteristics.

Reference Example 9 A solar cell having an i-type layer containing oxygen atoms was manufactured. When forming the i-type layer, in addition to the gas flowing in Reference Example 2 ,
The same conditions, the same method, and the same procedure as in Reference Example 2 were used except that O ₂ / He gas was introduced into the deposition chamber 401 at 10 sccm. The fabricated solar cell (SC Ex. 23) is (SC Ex. 1)
As in 6), it was found that the solar cell had better initial photoelectric conversion efficiency and better durability than the conventional solar cell (SC ratio 16).

The content of oxygen atoms in the i-type layer is determined by SI
As a result of examination by MS, it was contained almost uniformly, and 2 × 10 ¹⁹
(Pieces / cm ³ ).

Reference Example 10 A silicon solar cell having an i-type layer containing nitrogen atoms was manufactured. use when forming the i-type layer, in addition to the gas flowing in Reference Example 2, 5 sccm of NH ₃ / H ₂ gas, under the same conditions except for introducing into the deposition chamber 401 as in Reference Example 2, the same method, the same procedure Was. The manufactured solar cell (SC Actual 24) is (SC
As in the case of Example 16), it was found that the solar cell had better initial photoelectric conversion efficiency and durability than the conventional solar cell (SC ratio 16). Further, when the content of nitrogen atoms in the i-type layer was determined by SIMS, it was found to be substantially uniform and to be 3 × 1
0 ¹⁷ (pieces / cm ³ ).

Reference Example 11 A solar cell having an i-type layer containing oxygen atoms and nitrogen atoms was manufactured. When forming the i-type layer, in addition to the gas flowing in Reference Example 2 , O ₂ / He gas is 5 sccm and NH ₃ / H ₂
Ginseng except for introducing a gas 5 sccm, the deposition chamber 401
The same conditions, the same method, and the same procedure as in Example 2 were used. The manufactured solar cell (SC Ex 25) is similar to (SC Ex 16).
It was found that the solar cell had better initial photoelectric conversion efficiency and durability than a conventional solar cell (SC ratio 16).
Further, the contents of oxygen atoms and nitrogen atoms in the i-type layer were determined by SIM.
When adjusted with S, it was almost uniformly contained, and each contained 1
It was found to be × 10 ¹⁹ (pieces / cm ³ ) and 3 × 10 ¹⁷ (pieces / cm ³ ).

Reference Example 12 A solar cell was manufactured in which the hydrogen content of the i-type layer was changed in accordance with the silicon content. O ₂ / He gas cylinder S
Replace with iF ₄ gas (99.999% purity) cylinder
When forming the mold layer, the flow rates of the SiH ₄ gas, CH ₄ gas, and SiF gas were changed according to the flow pattern of FIG. The change in the band gap in the layer thickness direction of this solar cell (SC Ex 26) was determined in the same manner as in Reference Example 2 . It is shown in FIG.

Further, the content of hydrogen atoms and silicon atoms was analyzed in the thickness direction using a secondary ion mass spectrometer. As a result, as shown in FIG. 15C, it was found that the hydrogen atom content had a distribution in the layer thickness direction corresponding to the silicon atom content. This solar cell (SC actual 2)
Was determined the initial photoelectric conversion efficiency and durability characteristics of 6), ginseng
As with the solar cell of Example 2 , a conventional solar cell (SC ratio 1)
It was found to have better initial photoelectric conversion efficiency and durability than 6).

Reference Example 13 In forming the semiconductor layer of the solar cell shown in FIG. 1 by the manufacturing apparatus using the microwave plasma CVD method shown in FIG. 4, a silicon atom-containing gas (SiH ₄ gas) and a carbon atom-containing gas were used. A solar cell (SC Ex . 27) was produced in the same manner and in the same procedure as in Reference Example 2 , except that the gas (CH ₄ gas) was mixed at a distance of 4 m from the deposition chamber. The fabricated solar cell (SC
Example 27) was found to have better initial photoelectric conversion efficiency and durability than (SC ratio 16).

Reference Example 14 When a first p-type layer is formed by a gas diffusion method and an i-type layer is formed, a C ₂ H ₂ (acetylene) gas is used instead of a CH ₄ gas, and an RF electrode is further formed. A positive DC bias was applied to 410 to produce a solar cell in which RF power, DC bias, and μW power were changed.

First, an NH ₃ / H ₂ gas cylinder was charged with hydrogen for 10 minutes.
BBr ₃ gas (BBr ₃ / H ₂ gas) cylinder diluted to 1%, and the O ₂ / He gas cylinder was replaced with a C ₂ H ₂ gas (99.99% purity) cylinder. When forming the first p-type layer, the substrate temperature is 900 ° C., and the BBr ₃ / H ₂ gas flow rate is 50.
B was diffused under the diffusion conditions of 0 sccm and an internal pressure of 30 Torr. When the junction depth reaches about 300 nm, BB
The introduction of the r ₃ / H ₂ gas was stopped, and an n-type layer was formed under the same conditions as in Reference Example 2 . Next, when the i-type layer is formed, the C ₂ H ₂ gas is changed as shown in FIG.
A solar cell was manufactured by applying a C bias and changing the RF power, the DC bias, and the μW power as shown in FIG. 20-2. Otherwise, the procedure was the same as in Reference Example 2 .

The manufactured solar cell (SC actual 28) is (SC
As in the case of Example 16), it was found that the solar cell had better initial photoelectric conversion efficiency and durability than the conventional solar cell (SC ratio 16).

Reference Example 15 The triple solar cell shown in FIG. 17 was manufactured using the manufacturing apparatus shown in FIG. 4 using the microwave plasma CVD method of the present invention.

As the substrate, an n-type polycrystalline silicon substrate manufactured by a casting method was used. 50 × 50m
one surface temperature 100 ° C. of NaOH of substrates m ² (1 with H ₂ O
% Diluted) for 5 minutes and washed with pure water. N
When the surface immersed in aOH was observed with a scanning electron microscope (SEM), the surface had irregularities having a pyramid structure, and the substrate was textured (Textur).
ed) was confirmed. Next, ultrasonic cleaning with acetone and isopropanol, and further cleaning with pure water,
It was dried with warm air.

In the same procedure and in the same manner as in Reference Example 2 , hydrogen plasma treatment was performed, and the first surface was placed on the textured surface of the substrate.
, A first n-type layer, a first i-type layer, a second p-type layer, a second n-type layer, a second i-type layer, and a third
Were sequentially formed. When forming the second i-type layer,
The flow rate of the SiH ₄ gas and the flow rate of the CH ₄ gas were changed in accordance with the flow rate change pattern as shown in FIG. 5, and the third p-type layer had a laminated structure as in Reference Example 2 .

Next, on the third p-type layer, as in Reference Example 2 , a transparent electrode of ITO (In ₂ O ₃ + S
nO ₂ ) and 5 μm-thick silver (Ag) as a collecting electrode were vacuum-deposited. Then, as in Reference Example 2 , A
A 3 μm-thick back electrode made of g-Ti is vacuum-deposited,
Fabrication of a triple solar cell using microwave plasma CVD was completed. This solar cell is referred to as (SC Ex 29), and Table 9 shows the manufacturing conditions of each semiconductor layer.

<Comparative Example 29> In forming the second i-type layer of FIG. 17, the same as Reference Example 15 except that the SiH ₄ gas flow rate and the CH ₄ gas flow rate were changed according to the flow rate change pattern of FIG. A triple-type solar cell was produced by the same method and procedure. This solar cell (SC
Ratio 29).

[0334] The initial photoelectric conversion efficiency and durability characteristics of these fabricated triple solar cells were measured by the same method as in Reference Example 2, and (SC Ex 29) was higher than that of the conventional triple solar cell (SC ratio 29). Was found to have better initial photoelectric conversion efficiency and durability.

Reference Example 16 The solar cell of Reference Example 2 was fabricated using the manufacturing apparatus of FIG. 4 using the microwave plasma CVD method of the present invention, and was modularized and applied to a power generation system.

Under the same conditions, the same method, and the same procedure as in Reference Example 2 , 65 solar cells (SC Ex 16) of 50 × 50 mm ² were produced. EVA on 5.0mm thick aluminum plate
An adhesive sheet made of (ethylene vinyl acetate) was placed thereon, a nylon sheet was placed thereon, and the solar cells produced were further arranged thereon, and serialization and parallelization were performed. An EVA adhesive sheet was placed thereon, and a fluororesin sheet was further placed thereon, followed by vacuum lamination to form a module. The initial photoelectric conversion efficiency of the manufactured module was measured in the same manner as in Reference Example 2 . The module was connected to the circuit showing the power generation system of FIG. 18, and the load used was an external light that was lit at night. The entire system was powered by the battery and the power of the module, and the module was installed at an angle that could best collect sunlight. After one year, the photoelectric conversion efficiency was measured, and the light deterioration rate (photoelectric conversion efficiency after one year / initial photoelectric conversion efficiency) was obtained. This module is called (MJ actual 30).

[0337] <Comparative Example 30> conventional solar cell (SC ratio 16) were prepared 65, reference example
It was modularized in the same manner as 16 . This module is (M
J ratio 30). The same conditions as in Reference Example 16 ,
The initial photoelectric conversion efficiency and the photoelectric conversion efficiency one year later were measured by the same method and the same procedure, and the light deterioration rate was obtained.

As a result, the light degradation rate of (MJ ratio 30) was as follows with respect to (MJ actual 30).

MJ Actual 30 1.00 MJ Ratio 30 0.92 From the results described above, it was found that the solar cell module of this example had more excellent light degradation characteristics than the conventional solar cell module.

Embodiment 16 In this embodiment, using an n-type polycrystalline silicon substrate manufactured by a casting method, an i-type layer contains P and B atoms, and a second p-type layer has a laminated structure. The solar cell shown in FIG.

The substrate of 50 × 50 mm ² was made of HF and HNO
₃ Dipped in an aqueous solution (diluted to 10% with H ₂ O) for several seconds and washed with pure water. Next, the substrate was ultrasonically washed with acetone and isopropanol, further washed with pure water, and dried with warm air.

Next, the source gas supply device 200 shown in FIG.
A semiconductor layer was formed on a substrate by a manufacturing apparatus using a glow discharge decomposition method including a deposition apparatus 400 and a deposition apparatus 400. Hereinafter, the manufacturing procedure will be described.

After the preparation for film formation was completed in the same manner as in Example 1, the substrate 404 was subjected to hydrogen plasma treatment, and a first p-type layer, an n-type layer, an i-type layer, and a second p-type layer were formed on the substrate. A mold layer was formed. The procedure is described below.

To perform the hydrogen plasma treatment, the valve 20
03 was gradually opened, H ₂ gas was introduced into the deposition chamber 401, and the mass flow controller 2013 adjusted the flow rate of H ₂ gas to 500 sccm. The conductance valve was adjusted while watching the vacuum gauge 402 so that the pressure in the deposition chamber became 2.0 Torr, and the heater 405 was set so that the temperature of the substrate 404 became 550 ° C.
When the substrate temperature becomes stable, confirm that the shutter is closed.
W / cm ³ was set, microwave power was introduced into the deposition chamber through the dielectric window to generate glow discharge, the shutter 415 was opened, and hydrogen plasma treatment of the substrate 404 was started. After 10 minutes, the shutter was closed, the microwave power was turned off, the glow discharge was stopped, and the hydrogen plasma treatment was completed. After continuously flowing the H ₂ gas into the deposition chamber 401 for 5 minutes, the valve 2003 was closed and the inside of the deposition chamber 401 and the inside of the gas pipe were evacuated.

To form the first p-type layer, the valve 20
03 was gradually opened, H ₂ gas was introduced into the deposition chamber 401, and the mass flow controller 2013 adjusted the H ₂ gas flow rate to 50 sccm. The conductance valve is adjusted while watching the vacuum gauge 402 so that the pressure in the deposition chamber becomes 2.0 Torr.
The heater 405 is set to 50 ° C., and when the substrate temperature is stabilized, the valves 2001 and 200 are further increased.
5 was gradually opened, and SiH ₄ gas and B ₂ H ₆ / H ₂ gas were allowed to flow into the deposition chamber 401. At this time, the flow rate of the SiH ₄ gas was 5 sccm, the flow rate of the H ₂ gas was 100 sccm, and B ₂ H ₆
Each of the mass flow controllers was adjusted so that the / H ₂ gas flow rate was 500 sccm. The opening of the conductance valve 407 was adjusted while watching the vacuum gauge 402 so that the pressure in the deposition chamber 401 became 2.0 Torr.
Confirm that the shutter 415 is closed,
The power supply was set to 0.20 W / cm ³ , RF power was introduced, glow discharge occurred, shutter 415 was opened,
The formation of the first p-type layer on the substrate was started. Layer thickness 100n
When the first p-type layer of m is formed, the shutter is closed,
The RF power was turned off, glow discharge was stopped, and the formation of the first p-type layer was completed. The valves 2001 and 2005 are closed to stop the flow of the SiH ₄ gas and the B ₂ H ₆ / H ₂ gas into the deposition chamber 401, and the H ₂ gas is allowed to flow into the deposition chamber 401 for 5 minutes. Was closed, and the inside of the deposition chamber 401 and the inside of the gas pipe were evacuated.

To form the n-type layer, the auxiliary valve 40
8. Open the valve 2003 gradually, introduce H ₂ gas into the deposition chamber 401 through the gas introduction pipe 411, set the mass flow controller 2013 so that the H ₂ gas flow rate becomes 50 sccm, and set the pressure in the deposition chamber to 1 .0Tor
r with the conductance valve so that the substrate 4
Heater 405 so that the temperature of 04 becomes 350 ° C.
It was set. When the substrate temperature was stabilized, the valves 2001 and 2004 were gradually opened, and SiH ₄ gas and
PH ₃ / H ₂ gas was flowed into the deposition chamber 401. At this time, the flow rate of the SiH ₄ gas was ₂ sccm, and the flow rate of the H ₂ gas was 10 sccm.
Each mass flow controller was adjusted so that the flow rate of the PH ₃ / H ₂ gas was 200 sccm at 0 sccm.
The opening of the conductance valve 407 was adjusted so that the pressure in the deposition chamber 401 became 1.0 Torr. The power of the RF power source was set to 0.01 W / cm ³ ,
0, RF power is introduced, a glow discharge is generated, a shutter is opened, and an n-type layer is formed on the first p-type layer.
When the n-type layer having a thickness of 30 nm was formed, the shutter was closed, the RF power was turned off, the glow discharge was stopped, and the formation of the n-type layer was completed. The valves 2001 and 2004 are closed to stop the flow of the SiH ₄ gas and the PH ₃ / H ₂ gas into the deposition chamber 401, and the H ₂ gas is continuously flown into the deposition chamber 401 for 5 minutes. After closing, the inside of the deposition chamber 401 and the inside of the gas pipe were evacuated.

Next, in order to manufacture an i-type layer, the valve 20 was used.
03 was gradually opened, H ₂ gas was introduced into the deposition chamber 401, and the mass flow controller 2013 adjusted the H ₂ gas flow rate to 300 sccm. The conductance valve is adjusted so that the pressure in the deposition chamber becomes 0.01 Torr, and the heater 405 is set so that the temperature of the substrate 404 becomes 350 ° C. When the substrate temperature is stabilized, the valves 2001, 2002, 2004, and 20
05 is gradually opened, and SiH ₄ gas, CH ₄ gas, PH ₃
/ H ₂ gas and B ₂ H ₆ / H ₂ gas flowed into the deposition chamber 401. At this time, the flow rate of the SiH ₄ gas is 100 sccm,
H ₄ gas flow rate 30 sccm, H ₂ gas flow rate 300 sccc
m, PH ₃ / H ₂ gas flow rate was adjusted to ₂ sccm and B ₂ H ₆ / H ₂ gas flow rate was adjusted to 5 sccm by each mass flow controller. The pressure in the deposition chamber 401 is set to 0.
01 Torr conductance valve 407
The opening of was adjusted. Next, the power of the RF power source 403 is reduced to 0.
The power was set to 40 W / cm ³ and applied to the RF electrode 403.
After that, the power of a μW power supply (not shown) was increased to 0.20 W / cm ³
Is set in the deposition chamber 401 through the dielectric window 413.
W power was introduced to generate glow discharge, the shutter was opened, and the formation of an i-type layer on the n-type layer was started. Using a computer connected to the mass flow controller, SiH ₄ gas in accordance with the flow rate change pattern shown in FIG. 5, C
When the flow rate of the H ₄ gas was changed to produce an i-type layer having a thickness of 300 nm, the shutter was closed, the μW power supply was turned off to stop glow discharge, and the RF power supply 403 was turned off to complete the production of the i-type layer. Valves 2001, 2002, 2004,
Closing 2005, SiH ₄ gas into the deposition chamber 401,
The flow of CH ₄ gas, PH ₃ / H ₂ gas, and B ₂ H ₆ / H ₂ gas was stopped, and H ₂ gas was kept flowing into the deposition chamber 401 for 5 minutes. The inside of the gas pipe was evacuated.

Next, in order to form the second p-type layer, the valve 2003 was gradually opened, H ₂ gas was introduced into the deposition chamber 401, and the mass flow controller was adjusted so that the H ₂ gas flow rate became 300 sccm. Adjusted in 2013. The conductance valve is adjusted so that the pressure in the deposition chamber becomes 0.02 Torr, and the heater 405 is set so that the temperature of the substrate 404 becomes 200 ° C. When the substrate temperature becomes stable, the valves 2001, 2002, and 200
5 was gradually opened, and SiH ₄ gas, CH ₄ gas, H ₂ gas, and B ₂ H ₆ / H ₂ gas were flowed into the deposition chamber 401.
At this time, the flow rate of the SiH ₄ gas was 10 sccm, the flow rate of the CH ₄ gas was 5 sccm, the flow rate of the H ₂ gas was 300 sccm, and B ₂ H
Each mass flow controller adjusted the flow rate of ₆ / H ₂ gas to 10 sccm. The opening of the conductance valve 407 was adjusted so that the pressure in the deposition chamber 401 was 0.02 Torr. 0.30 μW power supply
W / cm ³ and the deposition chamber 4 through the dielectric window 413.
01, a glow discharge is generated, a shutter 415 is opened, and a lightly doped layer (A) is formed on the i-type layer.
Layer) has begun. When the A layer having a thickness of about 3 nm was formed, the shutter was closed, the μW power was turned off, and the glow discharge was stopped. The valves 2001, 2002, and 2005 are closed, and SiH ₄ gas, CH ₄ gas, B
_After stopping the inflow of ₂ H ₆ / H ₂ gas and continuing to flow H ₂ gas into the deposition chamber 401 for 5 minutes, the valve 2003 is closed,
The inside of the deposition chamber 401 and the inside of the gas pipe were evacuated.

Next, the valve 2005 was gradually opened, and B ₂ H ₆ / H ₂ gas was introduced into the deposition chamber 401 so that the flow rate became 10%.
It was adjusted with a mass flow controller so as to be 00 sccm. The conductance valve is adjusted so that the pressure in the deposition chamber becomes 0.02 Torr, the power of the μW power supply is set to 0.20 W / cm ³ , the μW power is introduced into the deposition chamber 401 through the dielectric window 413, and the glow is applied. Discharge is generated, shutter 415 is opened, and boron (B) is formed on layer A.
(Layer B) was started. After 6 seconds, the shutter was closed, the μW power was turned off, and glow discharge was stopped. The valve 2005 is closed and B is introduced into the deposition chamber 401.
_After stopping the inflow of ₂ H ₆ / H ₂ gas and continuing to flow H ₂ gas into the deposition chamber 401 for 5 minutes, the valve 2003 is closed,
The inside of the deposition chamber 401 and the inside of the gas pipe were evacuated.

Next, the A layer was formed on the B layer by the same method, the same procedure, and the same conditions as those described above. Further, a B layer was formed thereon by the same method, the same procedure, and the same conditions as those described above. Further, an A layer is formed thereon by the same method, the same procedure, and the same conditions as those described above, and a layer thickness of about 1
The formation of the second p-type layer of 0 nm was completed.

The auxiliary valve 408 is closed and the leak valve 4
09 was opened, and the deposition chamber 401 was leaked.

Next, ITO (In ₂ O ₃ + SnO ₂ ) having a thickness of 70 nm as a transparent electrode and silver (Ag) having a thickness of 5 μm as a current collecting electrode were vacuum-deposited on the second p-type layer. Subsequently, a back electrode having a layer thickness of 3 μm made of Ag-Ti was vacuum-deposited on the back surface of the substrate to complete the manufacture of the solar cell. This solar cell will be called (SC Ex 31), a first p-type layer,
Table 10 shows the conditions for forming the n-type layer, the i-type layer, and the second p-type layer.

<Comparative Example 31> Same as Example 16 except that the SiH ₄ gas flow rate and the CH ₄ gas flow rate were adjusted by the respective mass flow controllers according to the flow rate patterns shown in FIG. 6 when forming the i-type layer. Under the same conditions and procedure, a solar cell was produced. This solar cell will be referred to as (SC ratio 31).

< Reference Example 17-1> In forming the i-type layer, except that no PH ₃ / H ₂ gas was allowed to flow.
A solar cell was manufactured in the same manner and in the same procedure as in Example 16 . This solar cell is referred to as (SC Ex 31-1).

< Reference Example 17-2> A solar cell was manufactured in the same manner and in the same procedure as in Example 16 except that no B ₂ H ₆ / H ₂ gas was supplied when forming the i-type layer. This solar cell is referred to as (SC Ex. 31-2).

The fabricated solar cells (SC Ex 31) and (S
(C ratio 31) The initial photoelectric conversion efficiency (photovoltaic power / incident light power) and durability characteristics were measured.

As a result of the measurement, (SC ratio 31) and (SC actual 31-1) to (S
The initial photoelectric conversion efficiency of C Ex 31-2) was as follows.

(SC ratio 31) 0.53 times (SC actual 31-1) 0.77 times (SC actual 31-2) 0.76 times Further, for the solar cell of (SC actual 31), Ratio 3
The durability characteristics of 1) and (SC Ex 31-1) to (SC Ex 31-2) were as follows.

(SC ratio 31) 0.54 times (SC actual 31-1) 0.77 times (SC actual 31-2) 0.78 times Next, the fabricated solar cell (SC actual 31), (SC ratio 31) 3
1) and i of (SC actual 31-1) to (SC actual 31-2)
The composition analysis of the Si layer and the C atom in the layer thickness direction in the mold layer is performed in the same manner as the above-described composition analysis, and the relationship between the composition ratio of the Si atom and the C atom and the band gap is determined. When the change in the band gap was obtained, the same result as that in FIG. 8 was obtained. That is, (SC actual 31), (SC
The change of the band gap in the layer thickness direction of the actual sample 31-1) to (SC actual 31-2) is caused by the flow of Si into the deposition chamber.
It has been found that it depends on the flow rate ratio between the source gas containing Si (in this case, SiH ₄ gas) and the source gas containing C (in this case, CH ₄ gas).

Further, the composition in the layer thickness direction of P atoms and B atoms in the i-type layers of the solar cells (SC Ex 31), (SC Ex 31) and (SC Ex 31-1) to (SC Ex 31-2). Analysis was performed using a secondary ion mass spectrometer (IMEC-3 manufactured by CAMECA).
F). As a result of the measurement, P atoms and B atoms were uniformly distributed in the layer thickness direction, and the composition ratio was as follows.

P / (Si + C) B / (Si + C) (SC Ex 31) ３3 ppm to 10 ppm (SC ratio 31) ３3 ppm to 10 ppm (SC Ex 31-1) D. -10 ppm (SC Ex. 31-2) -3 ppm D. N. D. : Below the detection limit Next, a second layer having a laminated structure on a polycrystalline silicon substrate
Was formed, and its cross-sectional TEM (transmission electron microscope) image was observed. A second p-type layer was formed on a substrate by the same method and procedure as in Example 16 except that the deposition time of the B layer was changed to 12 seconds. The prepared sample is cut in the cross-sectional direction,
Observation of the state of the lamination of the A layer and the B layer in the p-type layer showed the same result as in FIG. 19, and the B layer having a layer thickness of about 1 nm and the A layer having a layer thickness of about 3 nm were alternately laminated. Was confirmed.

As seen from the above, the solar cell of this example is
It has been demonstrated that the solar cell has more excellent characteristics than the conventional solar cell (SC ratio 31).

Example 17 In Example 16 , several solar cells were manufactured by changing the position of the minimum value of the band gap (Eg) in the layer thickness direction, the size of the minimum value, and the pattern, and performing initial photoelectric conversion. Efficiency and durability properties were determined in the same manner as in Example 16 . At this time, it was the same as Example 16 except for the change pattern of the SiH ₄ gas flow rate and CH ₄ gas flow rate of the i-type layer. In the present embodiment, the solar cell having the band diagram shown in FIG. 12 was manufactured by changing the change pattern of the SiH ₄ gas flow rate and the CH ₄ gas flow rate.

Table 11 shows the results obtained by examining the initial photoelectric conversion efficiency and durability characteristics of these manufactured solar cells ((S
C-32-1)). As can be seen from these results, the band gap of the i-type layer smoothly changes in the layer thickness direction regardless of the magnitude and the change pattern of the minimum value of the band gap, and the position of the minimum value of the band gap is changed to the i-type layer. It has been found that the solar cell according to the example of the present invention, which is shifted in the p / i interface direction from the central position, is superior.

Example 18 In Example 16 , several solar cells were produced in which the concentration and type of the valence electron controlling agent in the i-type layer were changed, and the initial photoelectric conversion efficiency and durability were the same as in Example 16. In a particular way. At this time, the procedure was the same as in Example 16 except that the concentration and type of the valence electron controlling agent in the i-type layer were changed.

[0366] <Example 18 -1> i-type layer of the acceptor become valence electron controlling agent for the gas (B
₂ H ₆ / H ₂ gas) flow rate was reduced to 1/5, and the total H ₂ flow rate was the same as in Example 16 (SC Ex. 33-
When 1) was prepared, it was found that, similar to (SC Ex. 31), it had better initial photoelectric conversion efficiency and durability than a conventional solar cell (SC ratio 31).

[0367] <Example 18 -2> i-type layer of the acceptor become valence electron controlling agent for the gas (B
₂ H ₆ / H ₂ gas) flow rate is increased by 5 times, and the total H ₂ flow rate is
When the same solar cell (SC Ex 33-2) as in Example 16 was produced, the initial photoelectric conversion efficiency and the durability were better than the conventional solar cell (SC ratio 31), similarly to (SC Ex 31). It was found to have

[0368] <Example 18 -3> i-type layer of the donor to become valence electron controlling agent for the gas (PH ₃ /
H ₂ gas) to 1/5 the flow rate, total flow rate of H ₂ real
When the same solar cell (SC Ex 33-3) as in Example 16 was manufactured, the initial photoelectric conversion efficiency and the durability better than those of the conventional solar cell (SC ratio 31) were obtained, similarly to (SC Ex 31). It was found to have.

[0369] <Example 18 -4> i-type layer of the donor to become valence electron controlling agent for the gas (PH ₃ /
H ₂ gas) flow rate to 5 times, the total flow rate of H ₂ Example
When the same solar cell (SC Ex 33-4) as that of (SC Ex. 31-4) was manufactured, a conventional solar cell (S
It was found that the composition had better initial photoelectric conversion efficiency and durability than C ratio 31).

[0370] use cold instead of <Example 18 -5> i-type layer of the acceptor become valence electron controlling agent for the gas as B ₂ H ₆ / H ₂ gas, trimethyl aluminum liquid at normal pressure (TMA) A solar cell was manufactured. At this time, TMA (purity 9) sealed in a liquid cylinder was used.
(9.99%) was gasified by bubbling with hydrogen gas, and introduced into the deposition chamber 401, thereby producing a solar cell (SC Ex 33-5) using the same method and procedure as in Example 16 . . At this time, the flow rate of the TMA / H ₂ gas is 10 seconds.
ccm.

The manufactured solar cell (SC Ex. 33-5) is the same as the conventional solar cell (SC Comp. 31) as in (SC Ex. 31).
It was found to have even better initial photoelectric conversion efficiency and durability characteristics.

<Examples>18-6> PH as a gas for a valence electron controlling agent serving as a donor of the i-type layer
_Three/ H_TwoHydrogen sulfide (H_TwoS) Using gas
A solar cell was manufactured.Example 16NH_Three/ H_Two Gas bon
Hydrogen (H_TwoH) diluted to 100 ppm with_TwoS gas
(H_TwoS / H_Two) Change to cylinder,Example 16The same as
Solar cell (SC Ex 33-6) using the method and procedure
Produced. At this time, H_TwoS / H_TwoGas flow rate is 1scc
m and the other conditionsExample 16Same as.

The manufactured solar cell (SC Ex. 33-6) is the same as the conventional solar cell (SC Comp. 31) as in (SC Ex. 31).
It was found to have even better initial photoelectric conversion efficiency and durability characteristics.

Example 19 A solar cell shown in FIG. 1 was manufactured using a polycrystalline silicon substrate manufactured by a p-type casting method. The substrate is subjected to a hydrogen plasma treatment, and a first n-type layer, a p-type layer, i
A mold layer and a second n-type layer are sequentially formed, and Table 4 shows the formation conditions. When forming the i-type layer, the flow rate of the SiH ₄ gas and the flow rate of the CH ₄ gas were changed as shown in the pattern of FIG. 6 so that the minimum value of the band gap came near the i / p interface. The second n-type layer had a laminated structure as in Example 16 . Layers other than the substrate and the semiconductor layer were manufactured under the same conditions and the same method as in Example 16 . The fabricated solar cell (SC Ex. 34)
Is a conventional solar cell (SC ratio 3) as in (SC Ex 31).
It was found to have better initial photoelectric conversion efficiency and durability than 1).

Example 20 A solar cell having a maximum value of the band gap of the i-type layer near the p / i interface and a thickness of the region of 20 nm was manufactured. FIG. 13A shows a flow rate change pattern of the i-type layer. i
Except for changing the flow rate change pattern of the mold layer, it was manufactured using the same conditions and the same method as in Example 16 .

Next, the composition of the solar cell was analyzed in the same manner as in Example 16, and the change in the band gap in the layer thickness direction of the i-type layer was examined based on FIG. The result was as follows.

The manufactured solar cell (SC Actual 35) is (SC
As in the case of Example 31), it was found to have better initial photoelectric conversion efficiency and durability than the conventional solar cell (SC ratio 31).

<Comparative Example 35> There was a region having the maximum band gap near the p / i interface of the i-type layer, and several solar cells were manufactured with various thicknesses of the region. Example 1 except for the thickness of the region
It was produced using the same conditions and the same method as in Example 9. When the initial photoelectric conversion efficiency and durability characteristics of the manufactured solar cell were measured, when the thickness of the region was 1 nm or more and 30 nm or less, the actual
Even better initial photoelectric conversion efficiency and durability were obtained than in the solar cell of Example 16 (SC Ex 31).

Example 21 A solar cell having a maximum value of the band gap of the i-type layer near the n / i interface and a thickness of the region of 15 nm was manufactured. FIG. 13C shows a flow rate change pattern of the i-type layer. i
Except for changing the flow rate change pattern of the mold layer, it was manufactured using the same conditions and the same method as in Example 16 .

Next, the composition of the solar cell was analyzed in the same manner as in Example 16, and the change in the band gap in the thickness direction of the i-type layer was examined based on FIG. The result was as follows. The manufactured solar cell (SC Ex. 36) is the same as the conventional solar cell (SC Comp. 31) as in (SC Ex. 31).
It was found to have even better initial photoelectric conversion efficiency and durability characteristics.

<Comparative Example 36> There was a region having the maximum band gap near the n / i interface of the i-type layer, and several solar cells were manufactured with various thicknesses of the region. Example 2 except for the thickness of the region
It was manufactured using the same conditions and the same method as in Example 1. The initial photoelectric conversion efficiency and durability of the produced solar cell was measured, the thickness of the region is 1nm or more, carried out in the 30nm or less
Even better initial photoelectric conversion efficiency and durability were obtained than in the solar cell of Example 16 (SC Ex 31).

Example 22 A solar cell in which a valence electron controlling agent was distributed in the i-type layer was manufactured. FIG. 14A shows a change pattern of the flow rates of the PH ₃ / H ₂ gas and the B ₂ H ₆ / H ₂ gas. At the time of fabrication, PH ₃ / H ₂
Except for changing the flow rate of the gas and B ₂ H ₆ / H ₂ gas carried
The same conditions, the same method, and the same procedure as in Example 16 were used. The manufactured solar cell (SC Ex. 37) is similar to (SC Ex. 31).
It was found that the solar cell had better initial photoelectric conversion efficiency and durability than a conventional solar cell (SC ratio 31).
When the change in the layer thickness direction of P atoms and B atoms contained in the i-type layer was measured using a secondary ion mass spectrometer (SIMS), as shown in FIG. At the minimum position, the content of P atoms and B atoms was found to be minimum.

Example 23 A solar cell having an i-type layer containing oxygen atoms was manufactured. In the formation of the i-type layer, in addition to the gas flowing in Example 16, O ₂ / the He gas 10 sccm, except for introducing into the deposition chamber 401 is the same condition as in Example 16, the same method, using the same procedure . The fabricated solar cell (SC Ex. 38) is (S
As in the case of C Ex 31), it was found that it had better initial photoelectric conversion efficiency and better durability than the conventional solar cell (SC ratio 31).

Further, the content of oxygen atoms in the i-type layer was determined by SI
As a result of preparation by MS, it was almost uniformly contained and 2 × 10 ¹⁹
(Pieces / cm ³ ).

Example 24 A silicon solar cell having an i-type layer containing nitrogen atoms was manufactured. use when forming the i-type layer, in addition to the gas flowing in Example 16, 5 sccm of NH ₃ / H ₂ gas, the same conditions as in Example 16 except that introduced into the deposition chamber 401, the same method, the same procedure Was. The manufactured solar cell (SC Ex. 39) is the same as the conventional solar cell (SC Ex. 31) as in (SC Ex. 31).
It was found to have even better initial photoelectric conversion efficiency and durability characteristics. Further, when the content of nitrogen atoms in the i-type layer was determined by SIMS, it was found to be substantially uniform,
It was found to be 3 × 10 ¹⁷ (pieces / cm ³ ).

Example 25 A solar cell having an i-type layer containing oxygen atoms and nitrogen atoms was manufactured. In forming the i-type layer, in addition to the gas flowing in Example 16 , an O ₂ / He gas of 5 sccm and NH ₃ / H
Except that ₂ gas is introduced into the deposition chamber 401 at 5 sccm.
The same conditions, the same method, and the same procedure as in Example 16 were used.
It was found that the manufactured solar cell (SC Ex. 40) had better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cell (SC Ex. 31), similarly to (SC Ex. 31). Further, the content of oxygen atoms and nitrogen atoms in the i-type layer is represented by S
When adjusted by IMS, it was found to be almost uniform and contained 1 × 10 ¹⁹ (pieces / cm ³ ) and 3 × 10 ¹⁷ (pieces / cm ³ ), respectively.
cm ³ ).

Example 26 A solar cell was manufactured in which the hydrogen content of the i-type layer was changed corresponding to the silicon content. O ₂ / He gas cylinder S
Replace with iF ₄ gas (99.999% purity) cylinder
When forming the mold layer, the flow rates of the SiH ₄ gas, CH ₄ gas, and SiF ₄ gas were changed according to the flow pattern shown in FIG. The change in band gap in the layer thickness direction of this solar cell (SC Ex 41) was determined in the same manner as in Example 16 . It is shown in FIG.

Further, the content of hydrogen atoms and silicon atoms was analyzed in the layer thickness direction using a secondary ion mass spectrometer. As a result, as shown in FIG. 15C, it was found that the hydrogen atom content had a distribution in the layer thickness direction corresponding to the silicon atom content. This solar cell (SC actual 4)
Was determined the initial photoelectric conversion efficiency and durability properties of 1), the real
As with the solar cell of Example 16 , a conventional solar cell (SC ratio 3
It was found to have better initial photoelectric conversion efficiency and durability than 1).

Example 27 When forming the semiconductor layer of the solar cell shown in FIG. 1 by the manufacturing apparatus using the microwave plasma CVD method shown in FIG. 4, a silicon atom-containing gas (SiH ₄ gas) and a carbon atom-containing gas were used. A solar cell (SC Ex . 42) was produced in the same manner and in the same procedure as in Example 16 , except that the gas (CH ₄ gas) was mixed at a distance of 3 m from the deposition chamber. The fabricated solar cell (S
C sample 42) was found to have better initial photoelectric conversion efficiency and durability characteristics than (SC ratio 31).

Example 28 A first p-type layer was formed by a gas diffusion method, and when forming an i-type layer, C ₂ H ₂ gas was used instead of CH ₄ gas, and R
Applying a positive DC bias to the F electrode 410, RF power,
A solar cell in which DC bias and μW power were changed was manufactured.

When the first p-type layer is formed, the NH ₃ / H ₂ gas cylinder is filled with BBr ₃ gas (B
(Br ₃ / H ₂ gas) Replaced with a cylinder, substrate temperature 900 ° C,
BBr ₃ / H ₂ gas flow rate 500 sccm, internal pressure 30 Torr
When the junction depth reached about 300 nm under the diffusion condition of r, introduction of the BBr ₃ / H ₂ gas was stopped, and an n-type layer under the same conditions as in Example 16 was formed. Next, when forming the i-type layer,
The C ₂ H ₂ gas was changed as shown in FIG. 20A. Further, a positive DC bias was applied to the RF electrode 410, and RF power and DC power were applied.
A solar cell was manufactured by changing the bias and the μW power as shown in FIG. 20-2.

The fabricated solar cell (SC Ex. 43) is (SC
As in the case of Example 31), it was found to have better initial photoelectric conversion efficiency and durability than the conventional solar cell (SC ratio 31).

Example 29 The triple solar cell of FIG. 17 was manufactured using the manufacturing apparatus of FIG. 4 using the microwave plasma CVD method of the present invention.

The substrate used was an n-type polycrystalline silicon substrate manufactured by a casting method. 50 × 50mm
One side of the ^second substrate temperature 100 ° C. of NaOH (H ₂ O with 1%
) For 5 minutes and washed with pure water. Na
When the surface immersed in OH was observed with a scanning electron microscope (SEM), irregularities having a pyramid structure were formed on the surface, and the substrate was textured (Texture).
d) was confirmed. Next, the substrate was ultrasonically washed with acetone and isopropanol, further washed with pure water, and dried with warm air.

According to the same procedure and a similar method as in Example 16 ,
The substrate is subjected to hydrogen plasma treatment to form a first p-type layer on a textured surface of the substrate, and further a first n-type layer and a first i-type layer.
A mold layer, a second p-type layer, a second n-type layer, a second i-type layer, and a third p-type layer were sequentially formed. When forming the second i-type layer, the flow rate of the SiH ₄ gas and the flow rate of the CH ₄ gas were changed according to the flow rate change pattern shown in FIG.

Next, on the third p-type layer, as in Example 16 , a transparent electrode of ITO (In ₂ O ₃₎ having a thickness of 70 nm was formed.
+ SnO ₂ ), silver (Ag) with a layer thickness of 5 μm as a collecting electrode
Was vacuum deposited. Subsequently, a 3 μm-thick back electrode made of Ag—Ti was vacuum-deposited on the back surface of the substrate in the same manner as in Example 16 .

[0397] Thus, the fabrication of the triple solar cell using the microwave plasma CVD method is completed. This solar cell is referred to as (SC Ex. 44), and Table 13 shows the manufacturing conditions of each semiconductor layer.

<Comparative Example 44> In forming the second i-type layer of FIG. 17, the same as Example 29 except that the SiH ₄ gas flow rate and the CH ₄ gas flow rate were changed according to the flow rate change pattern of FIG. A triple-type solar cell was produced by the same method and procedure. This solar cell (SC
Ratio 44).

The initial photoelectric conversion efficiency and the durability of these fabricated triple solar cells were measured in the same manner as in Example 16. (SC Ex. 44) was higher than that of the conventional triple solar cell (SC ratio 44). Was found to have better initial photoelectric conversion efficiency and durability.

Example 30 A solar cell of Example 16 was manufactured using the manufacturing apparatus of FIG. 4 using the microwave plasma CVD method of the present invention, and was modularized and applied to a power generation system.

A 50 × 50 mm ² solar cell (SC Ex. 31) was used under the same conditions, the same method, and the same procedure as in Example 16 for 65 times.
This was produced. EV on 5.0mm thick aluminum plate
An adhesive sheet made of A (ethylene vinyl acetate) was placed thereon, a nylon sheet was placed thereon, and the solar cells produced were further arranged thereon, and serialization and parallelization were performed. An EVA adhesive sheet is placed thereon, and a fluororesin sheet is further placed thereon, and vacuum-laminated,
Modularized. The initial photoelectric conversion efficiency of the manufactured module was measured in the same manner as in Example 16 . The module was connected to the circuit showing the power generation system of FIG. 18, and an external light that was lit at night was used for the load. The entire system was powered by the battery and the power of the module, and the module was installed at an angle that could best collect sunlight. After one year, the photoelectric conversion efficiency was measured, and the light deterioration rate (photoelectric conversion efficiency after one year / initial photoelectric conversion efficiency) was obtained. This module is called (MJ Actual 45).

<Comparative Example 45> Sixty-five conventional solar cells (SC ratio: 31) were manufactured and modularized in the same manner as in Example 30. This module is (M
J ratio 45). The same conditions as in Example 30,
The initial photoelectric conversion efficiency and the photoelectric conversion efficiency one year later were measured by the same method and the same procedure, and the light deterioration rate was obtained.

As a result, the light degradation rate of (MJ ratio 45) was as follows with respect to (MJ actual 45).

Module Light Deterioration Ratio MJ Actual 45 1.00 MJ Ratio 45 0.75 The above results show that the solar cell module according to the embodiment of the present invention has more excellent light deterioration characteristics than the conventional solar cell module. It was found to have.

As described above, it was proved that the effects of the photovoltaic device of the present invention were exhibited irrespective of the device configuration, device material, and device manufacturing conditions.

[0406]

As described above, according to the present invention, recombination of photoexcited carriers is prevented, open voltage and carrier range of holes are improved, sensitivity of short wavelength light and long wavelength light is improved, and photoelectric conversion is performed. It is possible to provide a photovoltaic element with improved efficiency. Further, the photovoltaic element of the present invention can suppress a decrease in photoelectric conversion efficiency that occurs when light is irradiated for a long time. The photovoltaic element of the present invention is one in which the photoelectric conversion efficiency does not easily decrease when annealing is performed under vibration for a long time.

Further, according to the method for manufacturing a photovoltaic device of the present invention, a photovoltaic device having the above-mentioned effects can be formed with a high yield.

In addition, the power supply system using the photovoltaic element of the present invention exhibits excellent power supply capability even when the irradiation light is weak.

[0409]

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[Table 5]

[Table 6]

[Table 7]

[Table 8]

[Table 9]

[Table 10]

[Table 11]

[Table 12]

[Table 13]

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a layer configuration of a photovoltaic element of the present invention.

FIG. 2 is a conceptual diagram showing a band gap change in an i-type layer of the photovoltaic device of the present invention.

FIG. 3 is a conceptual diagram showing a band gap change in an i-type layer of the photovoltaic device of the present invention.

FIG. 4 is a conceptual diagram showing an example of a photovoltaic device manufacturing apparatus of the present invention.

FIG. 5 is a graph showing SiH ₄ and CH ₄ gas flow rate patterns.

FIG. 6 is a graph showing SiH ₄ and CH ₄ gas flow patterns.

FIG. 7 is a graph showing the relationship between the composition ratio of Si atoms and C atoms and the band gap.

FIG. 8 is a graph showing a change in a band gap in a layer thickness direction.

FIG. 9 is a graph showing the relationship between μW power and deposition rate.

FIG. 10 is a graph showing dependence of initial photoelectric conversion efficiency on μW power and RF power.

FIG. 11 is a graph showing pressure dependence of initial photoelectric conversion efficiency.

FIG. 12 is a conceptual diagram showing a change in a band gap in a layer thickness direction.

FIG. 13 is a graph showing a change in a flow rate pattern and a band gap in a layer thickness direction.

FIG. 14 is a graph showing changes in B ₂ H ₆ / H ₂ gas flow rate and PH ₃ / H ₂ gas flow rate in the layer thickness direction, and changes in B content and P content in the layer thickness direction.

FIG. 15 is a graph showing a band gap and a hydrogen atom content of an i-type layer in which hydrogen atoms are distributed, and a gas flow pattern when the i-type layer is formed.

FIG. 16 is a graph showing a change pattern of DC bias, RF power, and μW power.

FIG. 17 is a conceptual diagram showing a layer configuration of a triple solar cell.

FIG. 18 is a block diagram showing a power generation system of the present invention.

FIG. 19 is a diagram showing a TEM image of a p-type layer having a stacked structure.

FIG. 20: CH ₄ gas flow rate change, DC bias, RF
7 is a graph showing a change pattern of power and μW power.

[Explanation of symbols]

Reference Signs List 101 back electrode 102 n (p) -type silicon substrate 103 first p (n) -type layer 104 n (p) -type layer 105 i-type non-single-crystal semiconductor layer containing silicon atoms and carbon atoms 106 second p (n) type layer 107 transparent electrode 108 current collecting electrode 311, 321, 331, 341, 351, 361, 3
71 i-type layer with changing band gap 312, 322, 332, 333, 342, 343, 3
52, 353, 362, 372, 373 i-type layer with constant band gap 401 Deposition chamber 402 Vacuum gauge 403 RF power supply 404 Substrate 405 Heater 407 Conductance valve 408 Auxiliary valve 409 Leak valve 410 RF electrode 411 Gas introduction pipe 412 Microwave waveguide Unit 413 Dielectric window 415 Shutter 2000 Source gas supply device 2011 to 2017 Mass flow controller 2001 to 2077, 2021 to 2027 Valve 2031 to 2037 Pressure regulator 2041 to 2048 Source gas cylinder.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 31/04-31/078

Claims (9)

(57) [Claims] 1. A first p (n) type layer made of microcrystalline silicon, polycrystalline silicon or single crystal silicon on an n (p) type substrate made of polycrystalline silicon or single crystal silicon Composed of a non-single-crystal semiconductor material
In a photovoltaic device in which a (p) type layer, an i-type layer made of a non-single-crystal semiconductor material, and a second p (n) type layer made of a non-single-crystal semiconductor material are sequentially stacked, the i-type The layer contains at least silicon atoms and carbon atoms, the band gap changes smoothly in the layer thickness direction, and the position of the minimum value of the band gap is closer to the second p-type layer (p-type layer) than the center position of the layer thickness. ) Side and the donor in the i-type layer
Electron controlling agent to be the valence electron controlling agent and the valence electron controlling agent to be the acceptor
A photovoltaic element, wherein both are doped . 2. An interface between the i-type layer and at least one of an interface between the i-type layer and the second p (n) -type layer or an interface between the i-type layer and the n (p) -type layer. The photovoltaic device according to claim 1, wherein there is a maximum value of a band gap, and a region of the maximum value of the band gap is within 1 to 30 nm. 3. The valence electron controlling agent serving as the acceptor is a group III element of the periodic table, and the valence electron controlling agent serving as a donor is a group V element and / or a group VI element of the periodic table. The photovoltaic device according to claim 1 or 2 , wherein 4. The photovoltaic device according to claim 1, wherein the valence electron controlling agent is distributed in the i-type layer. 5. A photovoltaic device according to any one of claims 1 to 4, characterized in that oxygen atoms and / or nitrogen atoms in the i-type layer is contained. 6. The photovoltaic according to any one of claims 1 to 5, characterized in that hydrogen content contained in the i-type layer is changed to correspond to the content of silicon atoms Power element. 7. The first p (n) -type layer, wherein the n (p)
At least one of the mold layer and the second p (n) -type layer is composed of at least one element selected from carbon, oxygen and nitrogen and silicon, and a valence control agent. A layer containing a Group III element, a Group V element or a Group VI element of the Periodic Table, and a layer containing a Group III element, a Group V element, or a Group VI element of the Periodic Table as a main constituent element The photovoltaic device according to any one of claims 1 to 6 , wherein the photovoltaic device has a laminated structure. Wherein said photovoltaic to claim 1-7 or a photovoltaic element according to item 1, to monitor the voltage and / or current of the photovoltaic element storage battery and / or external load A control system for controlling the supply of power from the element,
A power storage system configured to store power from the photovoltaic element and / or supply power to an external load. 9. A first p (n) type layer made of microcrystalline silicon, polycrystalline silicon or single crystal silicon on an n (p) type substrate made of polycrystalline silicon or single crystal silicon Composed of a non-single-crystal semiconductor material
In a method for manufacturing a photovoltaic element, a (p) -type layer, an i-type layer made of a non-single-crystal semiconductor material, and a second p (n) -type layer made of a non-single-crystal semiconductor material are sequentially stacked. The mold layer is applied with a microwave energy lower than the microwave energy required to decompose the raw material gas for depositing a deposited film by 100% at a vacuum degree of 50 mTorr or less, and at the same time, higher than the microwave energy. R
A method for manufacturing a photovoltaic device, comprising applying F energy to the source gas.