JPS62189770A - Junction-type semiconductor light emitting device - Google Patents

Abstract

PURPOSE:To convert the wavelength of emitted light into the other wavelength and visualize the invisible light and employ an array structure to provide a precision display device and so forth by a method wherein a P-N junction which is extended along the direction perpendicular to a flat plate part is incorporated in a column-shape protrusion and exposed on its top surface and a fluorescent layer covering a part of the exposed junction is provided on the top surface. CONSTITUTION:A light emitting device is constituted by a flat plate part B composed of a substrate B1 and an upper layer B2, a column-shape protrusion P provided on the one side surface of the flat plate part B, a P-type side electrode E1 provided on the side circumferential surface of the column-shape protrusion P and on the top surface of the flat plate part B, an N-type side electrode E2 provided on the bottom surface of the flat plate part B, an SiO2 layer 5 formed over the whole top surface of the column-shape protrusion P, a fluorescent layer 7 provided on the SiO2 layer 5 and an insulating layer 10 provided between the top surface of the flat plate part B and the electrode E1. As the fluorescent layer 7 is provided on the top surface of the column-shape protrusion P with the SiO2 layer 5 between for the purpose of converting the wavelength of an emitted light from the light emitting part into the other wavelength, an infrared ray can be converted into a visible light. With this constitution, a display device can be provided by arranging the light emitting devices into single- or two-dimensional array structure.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a junction type semiconductor light emitting device that can be used as a light emitting diode or a semiconductor laser, and particularly relates to a junction type semiconductor light emitting device that can be used as a light emitting diode or a semiconductor laser. A light-emitting section consisting of a protrusion, an electrode provided at an arbitrary location on the flat plate part and the columnar protrusion, and having a pn junction extending perpendicularly to the flat plate part in at least the columnar protrusion, and including the pn junction. This invention relates to a junction type semiconductor light emitting device that converts the wavelength of light emitted from a semiconductor light emitting device.

(Prior art) A light emitting element that emits light in a direction perpendicular to a substrate (flat plate part) can be easily coupled with an optical fiber, and can also be used as a surface light emitter to form a one-dimensional or two-dimensional array structure. As a result, various applications such as OA information equipment are expected, and therefore development has been progressing in the research field of semiconductor lasers and light emitting diodes, and in recent years, many types have been put into practical use.

(Problems to be Solved by the Invention) A basic structural example of a junction type semiconductor light emitting device that emits light in a direction perpendicular to the substrate by a pn junction in a columnar protrusion formed perpendicularly to the substrate is as follows. As shown in FIG. 4, a flat plate part (B), a columnar projection (P) provided on one side thereof,
It consists of a p-side electrode (El) provided on the side peripheral surface of the columnar projection (P) and the top surface of the flat plate part (B), and an n-side electrode (E2) provided on the bottom surface of the flat plate part (B). , columnar process (P
) is a pn extending perpendicularly to the flat plate part (B).
There is a joint r'N1 in the flat plate part (B), and in the flat plate part (B)
) there is a pn junction 1) N2 extending in a direction parallel to . Then, a current is injected between the electrodes (El) and ([!2) so that light in the direction perpendicular to the flat plate part (B) can be obtained by the pn junction PNI.

Such light-emitting devices inherently have better light focusing properties than conventional light-emitting devices that emit light parallel to the flat plate, or surface-emitting devices that emit light perpendicular to the flat plate, and are more efficient than optical fibers. It can be combined well.

By the way, most of this type of light emitting elements use gallium-arsenide (GaAs) as a material for the purpose of emitting light. The reason for using GaAs is
Firstly, materials are inexpensive and can be supplied stably, and secondly, reactive ion etching and reactive ion beam etching can be easily performed.

However, GaAs has a narrow bandgap and emitted light with a long wavelength of 0.91 to 0.98W, which is infrared radiation.
I can't see the luminescence. Therefore, G, jA! There is no problem when using a light-emitting element consisting of L as a light-emitting diode or a semiconductor laser, but for example, when the light-emitting element is formed into a one-dimensional or two-dimensional array structure (arrayed) and used for a display device, etc. It is necessary to convert the light into visible light, but the reality is that no light-emitting device has yet been provided with such specific means.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a junction type semiconductor light emitting device that converts the wavelength of light emitted from a light emitting part so that it can be used alone or in an array as a display device.

[Means for solving problems]

The object consists of a flat plate part, a columnar protrusion provided on one side of the flat plate part, and an electrode provided at any location on the flat plate part and the columnar protrusion. A junction type semiconductor light emitting device having a pn junction extending to the columnar protrusion, characterized in that a phosphor layer is provided on the top surface of the columnar protrusion to cover at least a portion of the light emitting portion including the pn junction exposed on the top surface. This is achieved by a junction type semiconductor light emitting device.

By the way, the junction type semiconductor light emitting device as described above has a pn junction (pn junction PN
The original purpose is to obtain light by I), and the pn junction (
It is preferable that the pn junction PN2) does not exist, or even if it does exist, various measures are taken to prevent it from emitting light as much as possible.For example, as one measure, when forming a pn junction in the columnar protrusion and the flat plate part, it is preferable to By masking the upper surface of the substrate and diffusing impurities, it is possible to obtain a junction type semiconductor light emitting device in which a pn junction PN2 extending horizontally within the flat plate portion is not substantially formed.

In the present invention, it is preferable to use a junction type semiconductor light emitting device having such a structure.

In addition, the fluorescent layer has a wavelength of light emitted from the light emitting part within the columnar protrusion.
That is, GaAs, which is often used as a constituent material of columnar projections,
In the case of , it is used to convert the emission wavelength of 0.91 to 0.98p" into another wavelength, and as a phosphor, it is used to convert the emission wavelength 0.91 to 0.98p" into another wavelength. For example, when converting visible light to red, Yo, t4Ybe, zsEro are used as phosphors for converting 0 emission into visible light.
, oloCI (emission wavelength 0.66P), green, Y
e, 54Yb+,' +5Ero, r+F s
(emission wavelength 0.55 units), blue color is Y @, 1sY
bo, 5sTlo,. . 1 F, (emission wavelength 0.47
pJ may be used, and it may be used appropriately depending on the purpose.

[Effect]

The junction type semiconductor light emitting device of the present invention converts the wavelength of light emitted from the GaAs active layer by a phosphor layer provided on the top surface of the columnar projection.

〔Example〕

Embodiments of the junction type semiconductor light emitting device of the present invention will be described below based on the drawings.

FIGS. 1 and 2 show an embodiment of the junction type semiconductor light emitting device of the present invention. The junction type semiconductor light emitting device of this example is:
G'aAs is used as the material, and the light emitted by GaAs is converted into visible light so that it can be used in display devices, etc. As the phosphor, any one of the examples shown above can be selected. As is clear, this light emitting element has a flat plate part (B) having a two-layer structure consisting of a base Fi, (Bl) and an upper part Jig (B2), and a cylindrical part provided on one side of the flat plate part (B). Protrusion (P) and cylindrical protrusion (P)
The p-side electrode ([
B1) and the n-side electrode (B2
) and Si formed on the entire top surface of the cylindrical protrusion (P).
02 layer (5), a fluorescent layer (7) provided on this 5iot layer (5), and an insulating layer (10) interposed between the upper surface of the flat plate part (B) and the electrode (El). It consists of

A cylindrical pn junction PNI extending perpendicularly to the flat plate part (B) is formed in the cylindrical projection (P); Since the pn junction PN2 extending parallel to B) is not formed, when a current is injected between the electrodes (El) and (B2), p
The n-junction PNI emits light only in the direction substantially perpendicular to the flat plate part (B), and by providing the insulating layer (10), the electrode (El) on the upper surface of the flat plate part (B) is connected to the electrode (
It is possible to prevent the current from flowing vertically across the flat plate part (B) toward B2), and from the electrode (El) on the side peripheral surface of the cylindrical projection (P) across the p-n junction r'N1. This improves the injection efficiency of the current flowing toward the electrode (B2).

A light emitting element with this structure has a phosphor layer that covers the light emitting part exposed on the top surface of the cylindrical projection (P) in order to convert the wavelength of light emitted from the light emitting part within the cylindrical projection (P) into another wavelength. (7) is provided through the 5rOt layer (5) formed on the entire surface of the top surface, so infrared rays can be converted into visible light. Therefore, by forming this light-emitting element into a one-dimensional or two-dimensional array structure, it is possible to provide a precision display device for OA information equipment, etc., which is extremely useful in practice.

Next, an example of a method for manufacturing a light emitting device having the structure shown in FIG. 1 is to use GaAs as a substrate and epitaxially grow A J GaAs on the substrate. A case in which light emission of a wavelength by GaAs is converted into visible light will be briefly described.

First, a cylindrical protrusion (P
) to form an n-type A 1 xGa+-, As epitaxial growth layer, and this epitaxial growth layer is ion-etched using, for example, a reactive ion etching method to form a cylindrical protrusion (P). The remaining part of the epitaxial growth layer from which the cylindrical protrusion (P) is cut out becomes the upper JlI (B2) shown in the figure. This upper layer (B2) is not necessarily essential, and the cylindrical protrusion extends all the way to the substrate (B1). You may cut out (P). next,
After masking the top surface of the columnar projection (P) and the surface of the upper layer (B2) and leaving the side peripheral surface of the columnar projection (P) in an unmasked state, a p-type impurity (preferably zinc) is added. ) to form a cylindrical pn junction P within the cylindrical protrusion (P).
Form NI.

After the diffusion process, a p-side electrode (El) is placed on the side peripheral surface and top surface of the cylindrical projection (P) and the top surface of the upper layer (B2), and an n-side electrode (B2) is placed on the bottom surface of the substrate (B1). establish. Thereafter, by removing unnecessary electrode materials and mask layers by a lift-off method, the substrate (B1
) A junction type semiconductor light emitting device is manufactured which can be used as a light emitting diode having only a pn junction PNI extending in a direction perpendicular to the plate portion (B) and not having a pn junction PN2 in the flat plate portion (B).

After manufacturing the light-emitting element, if any of the aforementioned phosphors for converting light emission into visible light is coated on the top surface of the cylindrical protrusion (P), the light emission wavelength shown in Fig. 1 can be changed to other wavelengths. It is possible to produce a junction type semiconductor light emitting device having a fluorescent layer (7) that can be converted into a phosphor layer (7).

Although the light emitting device of the above-mentioned embodiment has an epitaxially grown layer of the same material as the substrate provided on the substrate, the substrate alone can also be used as a light emitting device.

However, in order to obtain even stronger light emission, it is preferable to provide an epitaxially grown layer. Also, fluorescent N (7
) does not need to be provided on the entire top surface of the cylindrical projection (P), and the wavelength of the emitted light can be converted by covering at least a part of the light emitting part exposed on the top surface, but from the viewpoint of conversion efficiency, It is more preferable to provide it so as to cover the entire light emitting part.

Furthermore, a fluorescent layer (7) is formed on the top surface of the cylindrical projection (P).
It is not necessary to form the 5ift layer (5) and provide it on the 5ift layer (5), and it may be provided directly on the top surface of the cylindrical projection (P).

FIG. 3 shows a light emitting device that takes the above matters into consideration.

In the light emitting device of this example, the phosphor layer (7) has a 510 m layer (
5) It is not provided on the entire top surface of the cylindrical projection (P), but has an annular shape that covers only the light emitting part exposed on the top surface, and the flat plate part (B) consists only of the substrate, and this The first except that the cylindrical protrusion (P) is formed from the substrate.
It is the same as the light emitting element shown in the figure, and can convert light emitted from the light emitting part into visible light. In the present invention, the electrodes (El) and (B2) are not limited to the positions and sizes shown in the examples, but can be provided at arbitrary positions (■) and with any desired size.
There are no particular restrictions on the method for forming the pn junction, such as impurity diffusion, p (or n) type semiconductor layer and n (
Alternatively, epitaxial vapor phase growth of a p) type semiconductor layer (in this case, heterojunction is also possible), or other methods may be used.

In the present invention, a pn junction PNI that contributes to vertical light emission is used.
The length of can be increased by increasing the height of the columnar projection (P), so it is preferable that the height of the columnar projection (P) is at least 2P, particularly at least 10P. It is possible to form columnar protrusions (P) on the surface of a semiconductor wafer by, for example, reactive ion etching.
) can be easily manufactured.

Regarding the present invention, the "vertical direction" in the columnar projection (P)
There is no need to limit the meaning of the term to mean only a direction perpendicular to the flat plate part (B) at an angle of 90°;
This also includes cases where the angle of inclination is somewhat larger or smaller. For example, the entire columnar projection (P) or only the coaxial cylindrical pn junction PNI formed inside the columnar projection (P) may be formed into a truncated conical shape with a larger diameter at the bottom to make it easier to couple to the optical fiber. The output light may be converged, or conversely, the output light may be formed into a truncated cone shape, which is the opposite of the above, and may be appropriately diverged depending on the purpose of use.

The light-emitting materials used in the junction type semiconductor light-emitting device of the present invention include GaAs, GaP5, which are ■-v group compound semiconductors.
AJGaAs, InPs InGaAsP
, InGaP, InAjlP.

GaAsP s GaN, InAsP, InA
Zn5e, which is a II-Vl group compound semiconductor such as sSb
% ZnS ZnO, CdSe, CdTe etc., T
PbTe, Pb5n, which are V-Vl group compound semiconductors
Te.

There are materials such as Pb5nSe, and SiC, which is a group IV-rV compound semiconductor, and each material can be applied by taking advantage of its advantages.

〔Effect of the invention〕

As is clear from the above, the junction type semiconductor light emitting device of the present invention has at least one light emitting portion including a pn junction exposed on the top surface of a columnar protrusion having p and n junctions extending perpendicularly to the flat plate portion. By providing a fluorescent layer covering a part of the top surface, the wavelength of the light emitted from the light emitting part can be converted to another wavelength, for example, a fluorescent layer made of a phosphor that converts the light emission into visible light. Since the light emission can be visualized by providing an array structure, it is possible to provide a precise display device, etc., which is extremely useful in practice.

[Brief explanation of drawings]

FIG. 1 is a perspective view of one embodiment of the junction type semiconductor light emitting device of the present invention, FIG. 2 is a sectional view of the light emitting device shown in FIG. 1, and FIG.
The figure is a sectional view of another embodiment of the junction type semiconductor light emitting device of the present invention.

Claims (1)

[Claims] Consisting of a flat plate part, a columnar projection provided on one side of the flat plate part, and an electrode provided at any location on the flat plate part and the columnar projection,
In a junction type semiconductor light emitting device having a pn junction extending in a direction perpendicular to a flat plate part in at least a columnar projection,
1. A junction type semiconductor light emitting device comprising a phosphor layer provided on the top surface of a columnar protrusion to cover at least a portion of a light emitting section including a pn junction exposed on the top surface.