JPS63104063A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To prevent generation of a ghost by forming a photoconductive amorphous silicon carbide a-SiC layer contg. a specific ratio of helium and group IIIa element of periodic table on a substrate. CONSTITUTION:The photoconductive amorphous silicon carbide layer 5 contg. 1X10<-5>-5atom% helium and 0.1-10,000ppm group IIIa element of periodic table is formed on the substrate 1. This photosensitive body is characterized by incorporation of 1X10<-5>-5atom% He element into the photoconductive a-SiC layer 5. The deterioration in the electrophotographic characteristics within the range where there are no obstacles in practicability is obviated in said range and the generation of the ghost is prevented by the incorporation of He. The electric chargeability is enhanced advantageously in a positive polarity if the group IIIa element of periodic table is doped into the a-SiC layer 5 in a 0.1-10,000ppm range, more preferably 0.1-1,000ppm range.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic photoreceptor comprising a photoconductive amorphous silicon carbide layer, and particularly to an electrophotographic photoreceptor that can be positively charged.

[Prior art and its problems]

In recent years, progress in electrophotographic photoreceptors has been remarkable, and with the development of copying machines, printers, etc. equipped with photoreceptors, various characteristics are required of the photoreceptors themselves. In response to this demand, amorphous silicon layers are attracting attention because they have excellent heat resistance, wear resistance, non-pollution properties, and photosensitivity characteristics.

However, the amorphous silicon (hereinafter abbreviated as a-3i) layer only has a dark resistivity of about 109 Ωcm unless it is doped with any impurity element, and when used in an electrophotographic photoreceptor, It is necessary to increase the charge retention ability by setting the dark resistivity to 10I2Ω·cm or more. For this purpose, it is possible to increase the resistance by doping a small amount of elements such as oxygen or nitrogen, but on the other hand, there is a problem that the photoconductivity decreases. Further, even if boron or the like is added, a high resistance can be expected, but a sufficiently satisfactory dark resistivity cannot be obtained and is only about 10 11 Ω·cm.

On the other hand, along with the development of doping agents as mentioned above, a-5i
A laminated photoreceptor has been proposed in which a photoconductive layer is laminated with another non-photoconductive layer.

For example, FIG. 2 shows this laminated photoreceptor, with groups Vi, (
A carrier injection blocking layer (2), an a-3i photoconductive layer (3), and a surface protection layer (4) are sequentially laminated on the layer 1).

According to this laminated light body, the carrier injection blocking layer (2) blocks injection of carriers from the substrate (1), and the surface protection layer (4) blocks the a-Si photoconductive layer (3). It protects and improves moisture resistance etc., but the N(2) of both
The purpose of both (4) and (4) is to increase the dark resistivity of the photoreceptor to increase the charging ability, and for that purpose, it is not necessary to make these layers photoconductive.

As described above, the conventionally well-known a-Si electrophotographic photoreceptor has a major feature in that the photocarrier generation layer is formed of an a-5i photoconductive layer, and as a result, it has excellent heat resistance, durability, and photosensitivity characteristics. However, because the dark resistivity is insufficient, the dark resistivity is increased by using doping agents or by making the photoconductor a laminated type. Carrier injection blocking layer (2) formed on the body
The surface protective layer (4) complements the defects of the a-5i photoconductive layer itself, and can be said to be a layer that can be substantially distinguished from the a-Si photoconductive layer (3).

In view of the above circumstances, the present inventors have already discovered that amorphous silicon carbide (hereinafter abbreviated as a-5iC) has photoconductivity and has a dark resistivity of 10'3 Ωcm or more regardless of the presence or absence of a doping agent. Furthermore, it has been discovered that by selecting a doping agent, an electrophotographic photoreceptor that can be positively charged can be obtained.

The reason why the above a-SiC layer could become an electrophotographic photoreceptor is as follows.
That layer has a large carrier mobility, and even 10-”
This is because the dark conductivity was less than (, Ω·cm)−', and a large charging ability was thereby obtained.

However, even with the a-5iC electrophotographic photoreceptor having such a high carrier mobility, satisfactory electrophotographic characteristics have not yet been obtained depending on the wavelength of the light source.

For example, if a primary light source such as a fluorescent lamp (with a spectrum shifted toward relatively short wavelengths) is used as a light source for static elimination, the optical memory effect during image exposure may cause a ghost phenomenon (the previous image may be completely distorted). (a phenomenon in which the previous image reappears with the formation of the next image) tends to occur more easily.

In order to solve this problem, it is effective to increase exposure by using a light source that emits long wavelength light as a light source for static elimination, and a light emitting diode array is a suitable light source for this purpose. However, when using this diode array, if forced light irradiation is performed to prevent the ghost phenomenon,
This causes problems such as a decrease in charging ability and an increase in dark decay. Furthermore, from a manufacturing cost perspective,
Light emitting diodes are much more expensive than fluorescent lamps, and a low-cost light source is desired.

In addition, the photoconductive a-SiC layer already proposed by the present inventors has a concentration of 0.1 to 10,000 ppm in the periodic table.
An electrophotographic photoreceptor that can be charged to positive polarity can be obtained simply by containing a group A element, and when further improving the electrophotographic properties by adding other doping agents, it is necessary to improve the electrophotographic properties in the film. It is desirable to incorporate other impurity elements without disturbing the atomic bonding state, thereby solving problems such as ghost phenomena.

[Purpose of the invention]

Therefore, the present invention was devised in view of soft soil, and its purpose is to substantially eliminate the need for a surface protective layer and a carrier injection blocking layer, to make the entire layer made of photoconductive a-SiC, and to An object of the present invention is to provide an electrophotographic photoreceptor that can prevent the occurrence of a ghost phenomenon.

Another object of the present invention is to provide an electrophotographic photoreceptor in which required electrophotographic properties can be improved without forcibly disturbing the atomic bonding state in the film.

Still another object of the present invention is to provide an electrophotographic photoreceptor that can be positively charged.

[Means for Solving the Problems] According to the present invention, 1 x 10 -5 to 5 atomic % helium and 0.1 to 10,000 ppm of an element of group Ma of the periodic table (hereinafter referred to as IIIa) are deposited on a substrate. Provided is an electrophotographic photoreceptor that can be charged to a positive polarity and is characterized by forming a photoconductive a-SiCN containing a group element (abbreviated as group element).

The present invention will be explained in detail below.

The electrophotographic photoreceptor of the present invention is characterized in that photoconductive a-5xCN contains helium (He) element within a predetermined range, and the photoconductive a-SiCf
As for f4, it has already been proposed by the present inventors that it can be a positively charged photoreceptor containing a TJia group element.

That is, according to FIG. 1, a photoconductive a-5iC layer (5) is formed on a four-electroconductive substrate (1) by, for example, glow discharge decomposition, and carbon and carbon are formed over the thickness direction of this layer. II
The RA group elements are contained in the same content ratio.

It was discovered that this resulted in a dark resistivity of 1013 Ω・cm or higher, which was also 1000 times higher than the bright resistivity.As will be clear from the examples described below based on this knowledge, a layer of this single composition is sufficient. Practical a-S
The fact that it became an iCi light body was an unexpected result.

Furthermore, when the present inventors charged this SiC photoreceptor to positive or negative polarity and compared the charging performance of the two, this a
-5iCH(5) with 0.1 to 10.00 of the ma group element
It has also been found that doping in the range of 0 ppm, preferably in the range of 0.1 to 11000 ppm, can advantageously increase the charging ability with positive polarity.

The reason why doping with Ma group elements makes it easier to be positively charged has not yet been elucidated and is still in the realm of speculation, but it is possible that the a-5iC layer is sufficiently charged to retain a positive charge. This is believed to be because it has high resistivity, is excellent in preventing injection of negative charges from the substrate, and has excellent charge mobility with respect to positive charges.

In addition, the ma group elements include B, Al, Ga, In
Among these, B is particularly desirable because it has excellent covalent bonding properties and can sensitively change semiconductor properties.

The reason why the a-SiCN of the present invention has photoconductivity is that amorphous silicon and carbon are essential constituent elements, and hydrogen elements (11) and halogen elements are added to terminate the dangling bonds. It is believed that photoconductivity is produced by containing the following within the required range. When the present inventors conducted experiments to confirm the presence or absence of photoconductivity by varying the carbon content ratio, they found that
a-5iCfi (5) preferably contains carbon in the range of 1 to 90 atoms 2, preferably 5 to 50 atoms χ,
Alternatively, the carbon content may be varied within this range in the layer thickness direction.

Further, the content of hydrogen element ()l) and halogen element is 5 to 50 atoms χ, preferably 5 to 40 atoms χ, optimally l
O to 30 atoms 2 are preferred, and H element is usually used. Since this H element is easily incorporated into the terminal portion of the dangling bond, the localized level density in the band gap is reduced, thereby providing excellent semiconductor characteristics.

Furthermore, a part of this H element may be replaced with a halogen element, whereby the localized level density of the a-3iC layer can be lowered and the photoconductivity and heat resistance (temperature characteristics) can be improved.

Its substitution ratio is 0.0 among all elements for dangling bond termination.
01 to 50 atoms 2, preferably 1 to 30 atoms 2. In addition, halogen elements include P, CLIBr, 1. At
Among these, the use of F is preferable because its large electronegativity increases the bonding between atoms, resulting in excellent thermal stability.

The present invention is characterized in that the photoconductive a-Si (: layer) contains 1 x 10-5 to 5 atoms χ of He element, and within this range, the electrophotographic properties described above are achieved. The ghost phenomenon can be prevented by not reducing the amount within a range that does not cause any practical problems, and by containing He.

That is, the present inventors focused on the fact that He exists as an inert gas at room temperature and does not contribute to interatomic bonding even if it is incorporated into the a-SiC film, and as a result of repeated experiments. , the positively chargeable photoconductive a-5iC layer containing He within a predetermined range does not deteriorate the electrophotographic properties; on the contrary, the a-5iC layer becomes denser due to the inclusion of He. It has been found that the film quality is improved and the ghost phenomenon is eliminated by this. Although this ghost phenomenon is noticeable when using a light source for static elimination, such as a fluorescent lamp, whose spectrum is shifted toward a relatively short wavelength side, a sufficient effect can be observed even when such a light source is used.

Although the inventors have not yet fully elucidated the problem that could be solved in this way, since He is an inert element, it has no bonding hands, and moreover, it has the smallest atomic radius.
Therefore, even if He is contained in the film, the bond network between Si and C is not disturbed, and in addition, the number of bonds of H to St is reduced, and as a result, the amorphous Si
It is thought that this is because the atomic structure of C and C becomes denser, the number of dangling bonds decreases, and defects such as vacancies that cause a decrease in carrier mobility no longer occur, and as a result, the ghost phenomenon no longer occurs.

The content of He element is related to the content ratio of Si and C and the type of element for dangling bond termination, but it is approximately 1X10-5
The range is preferably from 1 x 10-5 to 5 atoms 2, preferably from 1 x 10-5 to 5 atoms χ, and optimally from 1 x 10-5 to 3 atoms χ.

The thickness of the photoconductive a-SiC layer (5) as described above should be at least 5 μm or more, so that the surface potential is 1200 V or more, and the upper limit is within the range where image resolution and image blurring do not occur. The thickness is appropriately selected, and according to experiments by the inventor Yuki et al., it is preferably set within the range of 5 to 100 μm, preferably 10 to 50 μm.

Furthermore, when the dark decay curve and light decay curve of this a-SiC layer were determined, it was confirmed that it had a high surface potential and excellent photosensitivity characteristics, and also had a small residual potential.

Thus, the photoconductive a-3i of a single composition throughout the layer thickness direction
An electrophotographic photoreceptor that can be put into practical use with just the C layer is provided.

Therefore, based on the above results, the present inventors conducted further research and found that various N
? It has been found that the electrophotographic properties can be further improved by producing region II.

That is, in the electrophotographic photoreceptor of the present invention, the content ratio of the constituent element carbon or TI [group a element] is varied in the layer thickness direction, thereby forming a plurality of layer regions,
The following first to fourth aspects correspond to the number of areas iii.
An electrophotographic photoreceptor according to the embodiments described above can be obtained.

According to the present invention, in such an embodiment, from the substrate side to the photoreceptor surface side, the first layer region, the second layer region, and if necessary, the third layer region and the fourth layer. The method is characterized in that at least one or both of the second layer region and the third layer region contains 1×10 −5 to 5 atoms χ of the element I(e). This prevents the ghost phenomenon from occurring.

Hereinafter, the electrophotographic photoreceptor of the present invention will be described in detail regarding the first aspect and the second aspect, and the third aspect and the fourth aspect shall be based thereon.

First Aspect According to the first aspect B, there is provided an electrophotographic photoreceptor in which a photoconductive a-5iC layer is formed on a substrate, wherein the a-SiC layer covers at least a first layer region and a second layer region. positively charged, comprising a layer region, the first layer region being disposed closer to the substrate than the second layer region, and containing more Ma group elements than the second layer region; A possible electrophotographic photoreceptor is provided.

That is, according to the first aspect, at least the first element is contained in the photoluminescent a-3iC layer having a single composition shown in FIG. 1, and by changing the content ratio. This method generates a layer region and a second layer region, and this type B will be explained with reference to FIGS. 3 to 9.

In FIG. 3, a first layer region (
6) and a second layer region (7) are successively formed, both layer regions consisting of an integrated photoconductive a-5iC layer (5a); It is important that the second layer region (7) contains more Ma group elements than the second layer region (7), and that the second layer region (7) also contains a predetermined amount of He.

The second layer region (7) has a content of ll1a group elements of 0.1
It is appropriately controlled within the range of 10,000 ppm to 10,000 ppm, preferably 0.1 to 1,000 ppm, thereby positively charging and improving required electrophotographic properties such as surface potential and photosensitivity. is obtained. When the first layer region (6) containing more Ma group elements than this layer region is formed, the conductivity becomes thicker in the substrate side region of the photoconductive a-5iCN (5a). Injection of carriers from the substrate side is blocked, and optical carriers generated in the entire area of the a-SiC layer flow smoothly to the substrate, and as a result,
As the surface potential increases, the photosensitivity characteristics improve.

Further, in this second layer region (7), 1×10−5 lie is applied.
The content is preferably in the range of 5 to 5 atoms χ, preferably 1×10 −5 to 5 atoms χ, and optimally 1×10 −5 to 3 atoms χ, so that the ghost phenomenon does not occur.

In this way, when He is contained in the second layer region (7), as long as the lie content is set within the above range for the entire layer region (7), it is uniform throughout the layer thickness direction. -or it is contained in a non-uniform content distribution.

Furthermore, according to the first aspect, le is indispensably contained in the second layer region (7), but le may be optionally contained in the first layer region (6). good. When the first layer region (6) also contains He, I Xl0-5
The content may be within the range of 5 to 5 atoms χ, thereby not impairing the prevention of carrier injection from the substrate side and reducing the residual potential, thereby reliably preventing the ghost phenomenon from occurring. can.

Furthermore, according to the first aspect, the carbon content is
The settings may be made as shown in the figure. In these figures,
The horizontal axis shows the layer thickness from the substrate to the photoreceptor surface, and the vertical axis shows the carbon content. Furthermore, on this horizontal axis (6)
, Each range shown in (7) represents a first layer region and a second layer region.

That is, in FIG. 4, the carbon content ratio is constant throughout the entire layer, or in FIG. 5, the carbon content is reduced in the first layer region, whereas in FIGS. This indicates that the first 9M region contains more carbon than the second layer region, which further increases the surface potential and improves the photosensitivity. Furthermore, if the carbon content is varied in the layer thickness direction as shown in FIGS. 7 to 9, the surface potential and photosensitivity will be further increased and the residual potential will be reduced.

Second Aspect According to a second aspect, there is provided an electrophotographic photoreceptor in which a photoconductive a-5iC layer is formed on a substrate, wherein the a-3iC layer is formed in at least a first layer region and a second layer region. and a third layer region, the first layer region is located closer to the substrate than the second layer region, and the second layer region is located closer to the substrate than the third layer region,
In addition, the third layer region contains more carbon than the second layer region, and the second layer region contains 0.1 to 10,000 carbon.
0 ppm I The body is provided.

That is, according to this second aspect, as shown in FIG. 1O,
A third layer region (8) is further formed on the second layer region (7) shown in the first embodiment, and the carbon content of the third layer region (8) is adjusted to the second layer region (7). (7), and the first layer region (6), the second layer region (7) and the third layer region (8) are substantially integrated to form a photoquaternically conductive a-SiC layer. (5
b).

When this third N region (8) is formed, the a-3iC layer (
The dark resistivity on the surface side of 5b) increases, and the surface potential of the photoreceptor increases markedly.

That is, the third layer region (8) is a photoconductive a-SiC layer (5
It is formed to increase the resistance of the surface side of b),
This layer can be completely distinguished from the conventionally known surface protective layer (4) described in FIG. In addition, according to the photoreceptor of the permissive separation type, which is divided into a photocarrier generation layer and a carrier transport layer,
Although the carrier transport layer is made to have a high resistance of 1013 Ω・cm or more, this layer is not required to have particularly high photoconductivity, and the ratio of photoconductivity to dark conductivity is usually less than 1000 times. It's just set. On the other hand, the third layer region (8) has a photoconductivity that is 1000 times higher in this ratio or more, and can be sufficiently distinguished from the carrier transport layer.

The layer thickness of the third layer region (8) is not more than 1 times, preferably not more than 172 times, optimally not more than 17 times, compared to the second layer region (7).
4 times or less is preferable, and this can be said to be desirable because the surface potential is significantly improved, the photosensitivity is excellent, and the residual potential is small.

According to the electrophotographic photoreceptor of the second aspect of the present invention, the +Ie element is contained in both or either of the second layer region (7) and the third layer region (8). The content is 1 x 10-5 to 5 atoms χ, preferably 1 x 10-5 to 5 atoms χ, optimally 1 x 10-
It is sufficient to set it in the range of 5 to 3 atoms χ, thereby,
Ghost phenomenon no longer occurs.

Further according to a second aspect, the photoselectrogenic a-5iC layer (5b
) are as shown in FIGS. 11 to 16, where the horizontal axis shows the layer thickness from the substrate to the surface of the photoreceptor, and the vertical axis shows the carbon content. Furthermore, on this horizontal axis,
The respective ranges shown in (6), (7), and (8) represent the first layer region, the second layer region, and the third layer region.

According to FIGS. 12, 14, 15, and 16,
The carbon content is gradually changed over the layer thickness direction, which improves the surface potential, provides excellent photosensitivity, and reduces residual potential.

Third Aspect According to a third aspect, there is provided an electrophotographic photoreceptor in which a photoconductive a-SiC layer is formed on a substrate, wherein the a-5iC layer is formed in at least a first layer region and a second layer region. A third layer region, a third layer region, and a fourth layer region are sequentially provided from the substrate side toward the photoreceptor surface, and the third layer region is more dense than the second layer region, and the fourth layer region is better than the third layer region. The second layer region contains more carbon than the first layer region, and the second layer region contains 0.1 to 10,000 carbon.
ppm of group IIIa elements, and the first layer region contains more group Ma elements than the second layer region. provided.

That is, according to the third aspect, as shown in FIG.
A fourth layer region (9) is further formed on the third layer region (8) shown in the embodiment, and the fourth layer region (9) is formed on the third layer region (8).
contains more carbon than the region (8), and substantially integrates the first layer region (6) to the fourth layer region (9) to form a photoconductive a-SiCi! (5c).

This fourth layer region (9) contains more carbon than the third layer region (8) and has a high resistance, thereby increasing the charging ability and improving the surface potential. result,
A photoreceptor with high withstand voltage and long life can be obtained.

Further according to a third aspect, a photoconductive a-3iC layer (5C
) is as shown in FIGS. 18 to 21, where the horizontal axis represents the layer thickness from the substrate to the surface of the photoreceptor, and the vertical axis represents the carbon content. Furthermore, on this horizontal axis,
(6) (7) (8) The respective ranges shown in (9) are the first layer area, the second layer area, the third layer area and the fourth layer area.
represents the area of

According to FIGS. 19 and 21, the carbon content is gradually changed over the layer thickness direction, thereby improving the surface potential and photosensitivity, and reducing the residual potential.

Fourth Embodiment According to the embodiment of FIG. 4, photoconductive a-SiCN is formed on the substrate.
and an electrophotographic photoreceptor in which an a-SiC surface protective layer is sequentially formed, the photoconductive a-5iC layer comprising at least a first layer region, a second layer region, and a third layer region,
The first layer region is located closer to the substrate than the second layer region, and the second region is located closer to the substrate than the third layer region, and the third layer region has a lower carbon content than the second layer region. The second layer region contains a large amount of 0.1 to 10.000pp.
I A photoreceptor is provided.

That is, according to this fourth aspect, as shown in FIG.
Further a on the third layer region (8) shown in the second embodiment
-SiC surface protection layer (10) is formed, and this a-SiC surface protection layer (10) is formed. (10) is photoconductive a-5
It is formed to overcoat and protect the surface of the tC layer (5b).

The a-SiC surface protection layer (10) is the same as the photoconductive a-SiC layer (5b) in that it is made of a-SiC, but it has a high carbon content to make it highly hard, thereby protecting the surface. bring about action.

This a-SiC surface layer 11N (10) can be made photoconductive or non-photoconductive by changing the composition ratio of its constituent elements; increasing the carbon content tends to make it non-photoconductive. With this, high hardness characteristics are obtained, and high hardness a-
What is the name of 3iC surface protective layer?

Furthermore, according to the fourth aspect, the carbon content distribution is as shown in FIGS. 23 and 24, where the horizontal axis represents the layer thickness from the substrate to the photoreceptor surface, and the vertical axis represents the carbon content. There is. Furthermore, on this horizontal axis (6) (7) (8) (10)
The respective ranges shown in are the first layer region, the second layer region,
It represents the third layer region and the a-SiC surface protection layer.

Thus, according to the first to fourth aspects, an electrophotographic photoreceptor with significantly higher performance than the single-composition a-3iC9 photoreceptor shown in FIG. 1 is provided.

Further, according to the present invention, the single-composition a-5iCN and the a-5iC layers of the first to third embodiments are all composed of photoconductive a-3iC layers, which makes it possible to use electrophotography for practical use. However, a conventionally known surface protective layer may be formed on the surface of these a-SiCl.

Various materials can be used for this surface protective layer as long as they themselves have high insulation properties, high corrosion resistance, and high hardness characteristics, such as organic materials such as polyimide resin, a-3
iC, 5iOz+ Sin, Al2O2, SiC layer
5i3) L, , a-Si, a-Si:H, a-5i
:F, a-SiC: 11. Inorganic materials such as a-SiC:F can be used.

Next, a method for manufacturing the electrophotographic photoreceptor of the present invention will be described.

In forming the a-SiC layer according to the present invention, a glow discharge decomposition method, an ion blating method, a reactive sputtering method, a vacuum evaporation method, a CVD method, etc. can be used. The raw material to be used may be solid, liquid, or gas.For example, SiH4,5izH is used as a gaseous raw material for glow discharge decomposition method.
Si-based gas such as 6+5iJs, ClI4. C2H2,
There are C-based gases such as CzH4, CzHh, and C311s, and He gas may be used as a carrier gas.

In manufacturing the electrophotographic photoreceptor of the present invention, when an a-SiC layer is formed from a mixed gas of a silicon (Si)-containing gas and an acetylene (CzHz) gas by glow discharge decomposition, a significantly high rate of film formation is achieved. Desirable because it can be achieved. According to experiments repeatedly conducted by the present inventors, various Si-based gases mentioned above can be used as this Si-containing gas, but for example, SiH4 gas and CzH
When z gas was used, a film formation rate of 5 to 20 μm 7 hours was obtained. Incidentally, using SiH4 gas and CH4 gas, a-
When a 5iC film is produced, the deposition rate is about 0.3 to 1 μm/hour.

Next, a capacitively coupled glow discharge decomposition device used in an embodiment of the present invention will be explained with reference to FIG.

In the figure, 1st. Second. Third. 4th. Fifth. 6th tank (1
1) (12) (13) (14) (15) (16
), 5iHt+CJz+Bzt16(He
BJ6 (contains 8 ppm IT' when diluted with tleHe gas) + He, No gas is sealed, and fle is also used as a carrier gas. These gases correspond to the first. Second. Third. 4th. Fifth. Sixth regulating valve (17) (18) (19) (20
) (21) is released by opening (22), and its flow rate is controlled by the mass flow controllers (23) and (24).
(25), (26), (27), and (28). 5th tank (11) (1
2) The gas from (13) (14) (15) is the first
The No gas from the sixth tank (16) is sent to the main pipe (29) and to the second main pipe (30). Note that (31) and (32) are stop valves. First main pipe (29) and second main pipe (30)
The gas flowing through is sent to the reaction tube (33), and a capacitively coupled discharge electrode (34) is installed inside this reaction tube (33), and the high frequency power applied to it is 50W to 3KW. However, a suitable frequency is 1 MHz to 10 MHz. Inside the reaction tube (33), a cylindrical film-forming substrate (35) made of aluminum is placed on a sample holder (36).
36) is rotatably driven by a motor (37), and the substrate (35) is heated to about 200 to 400°C, preferably about 200 to 300°C, by suitable heating means.
It is heated uniformly to a temperature of 50°C. Furthermore, a reaction tube (33
) is connected to a rotary pump (38) and a diffusion pump (39) because a high degree of vacuum condition (discharge voltage of 0.1 to 2.0 Torr) is required during a-SiC film formation.

In the glow discharge decomposition device configured as above,
For example, an a-5iC film (containing He and B) is deposited on a substrate (
35), the first. Second. Third. Open the fifth regulating valve (17) (18) (19) (21) and add SiH4, Czllz+BzHb, )He
Release gas. The release amount is determined by a mass flow controller (2
3) (24) (25) controlled by in>,
The mixed gas of SiH4+CzHz+BzHa,lle is flowed into the reaction tube (33) via the first main pipe (29).

Then, the inside of the reaction tube (33) is 0.1 to 2.0 To
rr vacuum state, substrate temperature 200 to 400℃,
The high frequency power of the capacitive discharge electrode (34) is 50W to 3
Coupled with the Kw or frequency being set to 1 to 50 MHz, glow discharge occurs, gas decomposes, and an a-5iC film containing He and B is formed on the substrate at high speed.

〔Example〕

Next, embodiments of the present invention will be described in detail.

(Example 1) In this example, a photoconductivity meter SiC layer was formed on an aluminum film-forming substrate, and its conductivity with respect to the blending ratio of C2H2 gas was measured.

That is, using the capacitively coupled glow discharge decomposition device shown in FIG.
Tie gas is released from the fifth tank (15) at a flow rate of 101005e at a flow rate of secm, and the tie gas is released from the second tank (12).
CzHz gas is released at a flow rate of 10~101005e, and a-S with a thickness of about 5 μm is produced based on the glow discharge decomposition method.
When an iC film was manufactured and its dark conductivity and photoconductivity were measured, the results shown in FIG. 26 were obtained.

According to FIG. 26, the horizontal axis is C211□ gas flow rate (scc
m), the vertical axis represents the conductivity [(Ω・cm)-”J,
・The mark is a plot of dark conductivity, and the ○ mark is a l1e-Ne laser (wavelength 632.8nm, 100μm W/cm2)
This is a plot of photoconductivity when irradiated with , and a and b are respective characteristic curves.

As is clear from Fig. 26, the dark conductivity is io-'
<Ω・cm)-' or less, and the minimum is 1O-16(Ω
・cm) -' was obtained. Further, the photoconductivity was 1000 times or more as compared to the dark conductivity, indicating that this a-5iC layer had photoconductivity sufficiently satisfactory for use in electrophotographic photoreceptors.

(Example 2) In this example, when BtHb gas (or PH, gas) was introduced and the dark conductivity and photoconductivity were measured based on (Example 1), the results shown in Figure 27 were obtained. It was done.

In the figure, the horizontal axis is B for the total flow rate of SiH4 and CzHz.
This is the pure amount of ZH6 (this represents the absolute flow rate of 8 2 lb calculated from the dilution ratio of He gas).

Furthermore, a case where the pure amount of 82II6 is replaced with the pure amount of PH3 is also described as a reference example.

According to FIG. 27, the mark is a plot of dark conductivity,
The circle marks are plots of photoconductivity (this photosensitivity is obtained in the same manner as in (Example 1)), and C1d is the respective characteristic curve.

As is clear from FIG. 27, the photoconductivity is more than 1000 times that of the dark conductivity, and the a-3iC layer doped with P and B along with He has photoconductivity that is satisfactory for use in electrophotographic photoreceptors. .

(Example 3) In this example, the spectral sensitivity characteristics were measured for the a-5iC layer obtained by setting the gas flow rate as shown below based on (Example 2), and the results are shown in Figure 28. The spectral sensitivity characteristic e was as shown in . Note that this figure shows the photoconductivity when irradiated with equal energy light at each wavelength.

Gas flow rate SiH4 gas flow rate...1003ccm1003c Gas flow rate...103103c, H6 gas flow rate (38ppm
Contains)...10031003c Gas flow rate...10
1005c As is clear from FIG. 28, photosensitivity is observed in the visible light region, with deterioration in particular on the long wavelength side, so that it can be satisfactorily used as a photoconductor for electrophotography.

(Example 4) In this example, a-3 manufactured in the same way as (Example 3)
The characteristics of surface potential, dark decay, and light decay were measured for the iC layer (thickness: 30 μm). This measurement is +5.
The surface potential was positively charged with a 6KV corona charger, and the change in surface potential over time in the dark and the change in surface potential over time immediately after irradiation with 650 nm monochromatic light were tracked.

The results are shown in FIG. 29, where f and g are the dark decay curve and the light decay curve, respectively.

As is clear from FIG. 29, the surface potential is as large as about +620V, and the dark decay is about 27χ after 5 seconds, indicating excellent charge retention ability. It can also be said that it has excellent photoconductivity and low residual potential.

In addition, the a-5iC layer obtained in (Example 4) was heated to -5.6 KV.
When positively charged with a corona charger, the surface potential was several tens of volts.

When the He content of the a-SiC photoconductor manufactured based on this (Example 4) was measured, it was approximately 0.1 atom χ, and this photoconductor was connected to the positive electrode using a +5.6KV corona charger. As a result of electrostatic charging, imagewise exposure, and magnetic brush development, a high-quality image with high image density, high contrast, and no ghost phenomenon was obtained. However, a ghost phenomenon appeared in the electrophotographic photoreceptor manufactured under the same conditions except that H2 gas was introduced at a flow rate of 101005e instead of the above-mentioned lie gas introduction.

(Example 5) In this example, a photoreceptor of the first embodiment was manufactured.

That is, the aluminum drum for the substrate is installed in the reaction tube (33) of the capacitively coupled glow discharge decomposition apparatus shown in FIG.
A gas, CzHz gas from the second tank (12), B, H from the third tank and fourth tank (13) (14)
6 gas from the fifth tank (15) and He gas from the sixth tank (16) to form the first layer region and the second layer region under the manufacturing conditions shown in Table 1. did.

The thus obtained photoreceptor was positively charged with a corona charger connected to a +5.6 KV high voltage source in the dark.
Next, the surface of the photoreceptor was irradiated with spectrally monochromatic light (650 nm), thereby obtaining the following electrophotographic characteristics. Note that the residual potential is the value 5 seconds after the start of exposure.

Surface potential...+730V Photosensitivity...0.420m2erg-1 Residual level...
29V Next, as in (Example 4), it was charged to positive polarity, imagewise exposed, and developed with a magnetic brush. As a result, the image density was high;
A high-quality image with high contrast and no ghost phenomenon was obtained.

However, the carrier gas O1e gas 101005e used in forming the first layer region and the second layer region
flow rate), as well as B2H used to form the first layer region.
4 (containing 0.2χ) and Bztlb (38 ppm) diluent He gas used to form the second layer region were replaced with H2 gas, and the other conditions were exactly the same. A ghost phenomenon was observed on the body.

(Left below) (Example 6) In this example, a photoreceptor of the second embodiment was manufactured under the conditions shown in Table 2, and the following electrophotographic properties were obtained. Further, no ghost phenomenon occurred at all.

Surface potential: +770 ■ Photosensitivity: 0.39 cm2erg Residual potential: 25 V (blank below) (Example 7) In this example, the photoreceptor of the third embodiment was manufactured under the conditions shown in Table 3. As a result, the following electrophotographic characteristics were obtained. Further, no ghost phenomenon occurred at all.

Surface potential...+800■ Photosensitivity...0.40cm2erg-'Residual potential...
35V Furthermore, when the surface potential, dark decay, and light decay characteristics of this photoreceptor were measured in the same manner as in (Example 4), the 30th
The results shown in the figure were obtained. In the figure, h and i are a dark decay curve and a light decay curve, respectively.

As is clear from FIG. 30, the surface potential is significantly large, approximately +800V, and the dark decay is approximately 15χ after 5 seconds, indicating excellent charge retention ability.

(The following is a blank space) (Example 8) In this example, a photoreceptor according to the embodiment shown in FIG. 4 was manufactured under the conditions shown in Table 4, and the following electrophotographic characteristics were obtained. Further, no ghost phenomenon occurred at all.

Surface potential...+900V Photosensitivity...0.40cm"erg-'Residual potential...
40V (Hereinafter, blank) [Effects of the Invention] As described above, according to the electrophotographic photoreceptor of the present invention, the a-SiC having photoconductivity throughout the entire layer has a high dark resistivity, and the photosensitivity characteristics are improved. Due to the excellent properties of the present invention, it was possible to substantially eliminate the need for a surface protective layer and a carrier injection blocking layer, and as a result, an electrophotographic photoreceptor consisting only of a photosensitive a-5iC layer could be provided.

Further, according to the electrophotographic photoreceptor of the present invention, by containing a predetermined amount of lle in the film, a ghost phenomenon does not occur, and as a result, an electrophotographic photoreceptor with even higher performance can be provided.

Further, according to the electrophotographic photoreceptor of the present invention, by changing the content of carbon and MA group elements in the layer thickness direction, the surface potential is improved, the photosensitivity characteristics are enhanced, and the residual potential is significantly reduced. be able to. In particular, when the carbon content is varied in the layer thickness direction, the resistivity can be controlled and a desired layer area can be obtained, and as a result, an electrophotographic photoreceptor with significantly higher performance can be provided.

Further, according to the present invention, there is provided an electrophotographic photoreceptor for negative polarity that can be advantageously charged to positive polarity.

According to the electrophotographic photoreceptor of the present invention, since the electrophotographic photoreceptor itself has excellent charging ability and environmental resistance, there is no need to particularly provide a protective layer. When the surface has deteriorated due to filming, etc., the initial characteristics of the photoconductor can be maintained without being limited in the amount of polishing even if the deteriorated surface is repeatedly polished and regenerated with an abrasive. This makes it possible to stably supply a good initial image over a long period of time.

Furthermore, when a conventional a-Si photoreceptor is used for a long period of time, local discharge damage on the photoreceptor surface is likely to occur due to corona discharge, which causes spots to appear on the image. However, according to the present invention, a-5i
The dielectric constant of a-5iC is ε=12, while the dielectric constant of a-5iC is ε=12.
7, it has excellent charging ability, and as a result, even if the surface potential is raised, the above-mentioned discharge breakdown will not occur.As a result, high quality and high reliability electrophotographic photosensitive materials can be produced. The body is provided.

Furthermore, when the electrophotographic photoreceptor of the present invention is compared with a conventional a-Si photoreceptor, the problem with this a-5t bad sensitivity is that it has poor moisture resistance, which tends to cause image deletion, and that it has poor charging ability. To solve this problem, a heater is used to heat the photoreceptor when using the a-3i photoreceptor, thereby preventing the ghost phenomenon from occurring. On the other hand, the electrophotographic photoreceptor of the present invention has an advantage in that it is not necessary to use a heater as described above because it has excellent moisture resistance and charging ability.

Further, compared to the a-5i photoreceptor, the electrophotographic photoreceptor of the present invention can obtain a wide range of spectral sensitivity characteristics (peak 600 to 700 nm) by simply changing the carbon content, and can increase the photosensitivity itself. Furthermore, there is an advantage that sensitization on the long wavelength side is also possible by doping with an impurity element as necessary.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the layer structure of the electrophotographic photoreceptor of the present invention, FIG. 2 is an explanatory diagram showing the layer structure of a conventional electrophotographic photoreceptor, and FIG. Explanatory diagrams showing the layer regions of the photoreceptor, FIG. 4, FIG. 5, FIG. 6, FIG. 7, FIG. 8, and FIG. 9 respectively show the carbon content of the photoreceptor of the first embodiment according to the present invention. FIG. 1O is an explanatory diagram showing layer regions of a photoreceptor according to the second embodiment of the present invention, FIGS. 11, 12, 13, 14, 15, and 16. The figures are an explanatory diagram showing the carbon content of the photoconductor of the second embodiment according to the present invention, FIG. 17 is an explanatory diagram showing the layer region of the photoconductor of the third embodiment according to the present invention, and FIG. Figure 19, 2nd
FIG. 0 and FIG. 21 are explanatory views showing the carbon content of the photoreceptor of the third embodiment of the present invention, respectively, and FIG. 22 is an explanatory view showing the layer regions of the photoreceptor of the fourth embodiment of the invention. , 23rd
24 and 24 are explanatory diagrams showing the carbon content of the photoreceptor of the fourth embodiment of the present invention, and FIG. 2
Figure 6 is a diagram showing the electrical conductivity versus the flow rate ratio of CzH A diagram showing the spectral sensitivity characteristics, FIG. 29 is a diagram showing the dark attenuation and optical attenuation of the amorphous silicon carbide layer, and FIG. 30 is a diagram showing the dark attenuation and optical attenuation of the amorphous silicon carbide layer of the third embodiment. 1...Substrates 5, 5a, 5b, 5c...Photoconductive amorphous silicon carbide layer 6...First layer region 7...Second layer region 8...Third Layer region 9...Fourth layer region 10...Amorphous silicon carbide surface protective layer Patent applicant (663) Kyocera Corporation Takao Kawamura

Claims (1)

[Claims] A photoconductive amorphous silicon carbide layer containing 1×10^-^5 to 5 atomic % helium and 0.1 to 10,000 ppm of Group IIIa elements of the periodic table is formed on the substrate. An electrophotographic photoreceptor that can be positively charged.