JPH02305482A - Semiconductor photoelectric conversion device - Google Patents

Abstract

PURPOSE:To obtain a photoelectric conversion device with an optical output of high density and quality by a method wherein an electrode formed on the surface of a semiconductor substrate where a semiconductor part is formed is formed into such a shape that it is large enough to cover the semiconductor part and provided with a through-hole of predetermined size. CONSTITUTION:When a current is applied between electrodes formed on both the sides of a one-way conductivity type semiconductor substrate, and light is emitted adjacent to the junction between the electrodes and a semiconductor part in the light emitting region of the semiconductor substrate. In this case, an electrode 17 formed on the surface of the semiconductor substrate where the semiconductor part is formed is formed large enough to cover the semiconductor part and provided with a through-hole 17d of predetermined size. Therefore, the emitted light is outputted only through the through-hole 17d, so that the same effect as a case in which a light emitting region is made narrow can be obtained. By this setup, when a semiconductor part is formed through a diffusion technique, a mask used for diffusion is not required to be unnecessarily improved in processing accuracy and a light emitting region of high density and quality can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to semiconductor photoelectric conversion devices such as light emitting diodes (LEDs).

2. Description of the Related Art In recent years, so-called optical printers using electrophotographic technology have been developed as printing devices. This optical printer uses a plurality of LEDs (light emitting diodes) arranged in the axial direction of the photosensitive drum to form an electrostatic latent image on the photosensitive drum in an electrophotographic device.
A printer head containing an ED array is used.

FIG. 11 shows a cross-sectional view of the configuration of a typical conventional LED I, and FIG. 12 is a graph showing the output characteristics of the LED I. In LEDI, for example, a p-type semiconductor region 3 is formed on one surface of an n-type semiconductor substrate 2, electrodes 4 and 5 are formed on both surfaces of the n-type semiconductor substrate 2, and an arrow mark A1 is formed between these electrodes 4 and 5. Light emitting output can be obtained by applying current in the direction. The width W1 of the light emitting region 6 that outputs light is approximately 50 μm when the ED array is, for example, 300 DPI (dots/inch).

When the value of the current flowing between the electrodes 5 and 4 is increased in EDI, the optical output increases to line I 1, 12 shown in FIG.
．． It gradually increases like 13.

Problem to be Solved by the Invention In such an LEDI, the light emission width W1 and the LED
According to experiments by the inventor of the present invention, the relationship between the printing line width on the recording paper of an optical printer using an array and the printing line width can be expanded several times as shown by line 14.15 in Fig. 13. was detected. In recent years, printing devices or printing devices used in computers, word processors, etc. are required to have higher output densities, and it is therefore desired to shorten the printing line width.

However, in conventional optical printers, the technology for shortening the print line width is not adopted, especially regarding the structure of LEDl. In other words, the width W1 in FIG.
In order to reduce the light emitting region 6, it is necessary to narrow the light emitting region 6. However, when forming the p-type semiconductor region 3 on the n-type semiconductor substrate 2 by diffusion technology, the mask used for diffusion is In forming the upper part selectively,
This requires extremely high-precision positioning technology, making it difficult to form in practice.

An object of the present invention is to solve the above-mentioned technical problems and provide a semiconductor photoelectric conversion device that can obtain high-density and high-quality optical output.

Means for Solving the Problems The invention as set forth in claim 1 forms a semiconductor portion of one conductive type in a predetermined light emitting region of a semiconductor substrate of one conductive type, and forms electrodes on both surfaces of the semiconductor substrate, In a semiconductor photoelectric conversion device that obtains light emission output by passing current between electrodes, the electrode formed on the surface of the semiconductor substrate on which the semiconductor portion is formed has a size that covers the semiconductor portion,
The semiconductor charging/converting device is characterized in that it is carried in a shape having a through hole of a predetermined size.

The invention according to claim 2 is a semiconductor photoelectric conversion device, characterized in that the semiconductor portions of the semiconductor substrate are formed in a shape in which the depths of their contact surfaces from the surface of the semiconductor substrate have a plurality of levels. It is.

According to the invention of claim 1 for ft, electricity is passed between the electrodes formed on both surfaces of a one-sided conductive type semiconductor substrate, and light is generated near the junction surface with the semiconductor portion in the light emitting region of the semiconductor substrate. Ru. At this time, the electrode formed on the surface of the semiconductor substrate on which the semiconductor portion is formed has a size that covers the semiconductor portion, and is formed in a shape having a through hole of a predetermined size. The light thus generated is output only from the through hole, and the same result as when the light emitting region is formed narrowly can be obtained.

According to the invention of claim 2, it is possible to obtain a high-density and high-quality light-emitting region without unnecessarily improving the processing accuracy of the mask used for diffusion when forming a semiconductor part by diffusion technology. Accordingly, the semiconductor portions of the semiconductor substrate are formed in such a shape that the depths of their bonding surfaces from the surface of the semiconductor substrate have a plurality of levels. It has been discovered that the light output level of a semiconductor photoelectric conversion device increases as the depth of the bonding surface becomes relatively smaller when the amount of current applied is the same.Therefore, the above configuration improves the photoelectric conversion efficiency. be able to.

Embodiment FIG. 1 is a plan view of LED II, which is a semiconductor photoelectric conversion device according to an embodiment of the present invention, and FIGS. It is a cross-sectional view,
Figure 4 shows an optical printer head 1 in which LEI) 11 is used.
2 is a plan view of FIG. This embodiment will be described with reference to these drawings.

The optical printer head 12 according to this embodiment is used in a so-called optical printer using electrophotographic technology, and is aligned in the axial direction of the photoreceptor drum when forming an electrostatic latent image on the photoreceptor drum by light irradiation in an electrophotographic apparatus. It includes a number of LEDs 11 arranged in a line.

Substrate 1 made of electrically insulating material of optical printer head 12
A common lead wire 14 is formed on the surface of 3. The LED 11 is formed on the common lead 14, and its cathode is connected, for example, to act as one electrode for applying power to the LED 11 to cause it to emit light.

A driving integrated circuit 15 is provided on the substrate 13 in parallel to the direction in which the light emitting diodes 11 are arranged.

The connection lead wires 16 are formed on the substrate 13 and are connected to the individual electrodes 17 of the light emitting diodes 11 and the output terminals 15εt of the a-product circuit 15 via bonding wires 18, respectively. Input terminal 15b of integrated circuit 15 is connected to individual drive leads 20 on substrate 13 by a single bonding wire. The individual drive lead wires 20 are connected to a large number of printed wirings 22 provided on a flexible circuit wiring board 21.

1121st to 3rd I2I'i:9 again, LED
Reference numeral 11 shows ASH3 (arsine) and PH on an n-type first semiconductor layer 25 made of GaAs (gallium-arsenide).

A gas containing appropriate amounts of (phosphine) and Ga (gallium) is brought into contact to grow an n-type second semiconductor layer 26 made of GaAsP (gallium-arsenic-phosphorus) on the surface thereof.
Next, a diffusion mask layer 27 made of 5izNi (silicon nitride) or SiO2 (silicon oxide) is formed on the surface of this second semiconductor layer 26. This mask layer 27
An opening 28 for diffusion is formed by, for example, a photoetching technique.

Thereafter, Z[1 (zinc) gas is brought into contact with the opening 28 to diffuse Zr+ into a predetermined region of the second semiconductor 126 to form an n-type semiconductor layer 29 as a semiconductor portion. The p-type semiconductor layer 29 and the second semiconductor layer 26 constitute a pntl&, and the light emitting region 3 of the LIXL2
0 is formed.

Individual electrodes 17 as shown in FIG. 1 are formed overlying the light emitting region 30. The individual wire 8ii17 has a connecting portion 17a used for connection with the bonding wire 18 and substantially rectangular branch portions 17b, 17 integrally formed with the connecting portion 17a.
c, and a through hole 17d is formed between them.

The width D1 of the through hole 17d in the left-right direction in FIG. 1 is 1/4 to 1/4 of the desired print line width when printing on recording paper in electrophotography using the optical printer 12 of this embodiment.
A value of about 115 is selected.

Furthermore, when forming the individual electrodes 17 on the light emitting region 30, due to mask alignment accuracy etc. when forming the individual electrodes 17 using a technique such as photoetching,
Figure 1 ±δ (δ=5
It is known that a positioning error of ~10 μm) occurs. Therefore, the width D2 of the technical parts 17b and 17c in the left-right direction in FIG. D3 is selected as follows: 0 The first part of the part covered by the technical parts 17b and 17c of the light emitting region 30 when the individual electrode 17 is properly arranged on the light emitting region 30.
Length L3 in the left-right direction of the figure. With respect to L4, the positional shift occurs as shown in FIG. 5(1), and for example, the branch 17c
For example, when the edge facing the through hole 17d and the edge of the light emitting fjR region 30 almost match, for example, the width D2 of the branch 17b
However, if D2=L3+δ (1) is selected, it is possible to prevent the light emitting region 30 from protruding from the technical part 17b.

Similarly, the width D3 of the branch portion 17c may be selected as follows: D3=L4+δ (2).

On the other hand, the length L5 of the branch parts 17b and 17c in the vertical direction in FIG.
For the same reason, L5=12+2xδ...(3) is selected, that is, even if the individual electrode 17 has a positional deviation of 1δ in the vertical direction in Figure 1, as shown in Figure 5 (2). , a light emitting area having a width D1 and a length L2 can be realized in the through hole 17d.

By employing the individual electrodes 17 having such a structure and shape, when forming the semiconductor layer 29 on the second semiconductor layer 26 by a diffusion technique, it is not necessary to use an unnecessarily high-precision positioning technique, and The selectable light emitting region width can be selected within the range of 17/4 to 115 of the expected print line width. This enables high-density printing.

FIG. 6 is a plan view of an LED 31 according to another embodiment of the present invention, and FIG. 7 is a cross-sectional view taken along the section line ``---'' in FIG. 6 and a diagram showing the characteristics of the LED 31. The LED 31 will be described with reference to these drawings. This embodiment is similar to the previous embodiment, and corresponding parts are given the same reference numerals.

The noteworthy point of this embodiment is that a plurality of openings 28a, 28b, 28c, and 28d were formed in the mask layer 27. That is, as shown in FIG. 7(1), the mask layer 27
The portion of the second semiconductor layer 26 covered with the strip 27a has a shallow contact surface, and the portions corresponding to the openings 28a to 28d have deep contact surfaces.

The driving current injected from the individual electrode 17 in such an LED 31 is indicated by the arrow A2 in FIG.
The current density along the left-right direction of FIG. 7(1) is shown in FIG. 7(2). The emission intensity distribution obtained by such a current density distribution is shown in FIG. 7(3). That is, the emission intensity in the portion of the mask layer 27 corresponding to the band-shaped portion 27a has peaks PL, P2. P3 appears, and a peak P3 also appears in the portions of the mask layer 17 facing the openings 28a and 28d.
4. P5 appears.

That is, two p-type semiconductor layers and an n-type second semiconductor layer 26
The light generated at the prl interface with the semiconductor layer 2
One part of the light is absorbed and the remaining light is emitted to the outside. Therefore, when the thickness of the semiconductor layer 29 that absorbs light changes, the emission intensity also changes in correlation with this change.

FIG. 8 is a cross-sectional view schematically showing a configuration example of the LED 31 of this embodiment, and FIGS. 9 and 10111 are diagrams illustrating its characteristics. Experiments were conducted by setting the free end portion of the individual electrode 17 facing the light emitting region 32 at two types of electrode positions P1 and P2 as shown in FIG. 8, and the results shown in FIGS. 9 and 10 were obtained. .

That is, the relationship between the light emitting region 32 and the individual electrodes 27 at electrode position P1 is shown in FIG. 9 (1), and in the case of electrode position P2, it is shown in FIG. 10 (1).

The amount of emitted light in these cases is shown in FIG. 9 (2) and FIG. 10 (2), respectively.
The closer the free end portion is to the interface between the two semiconductor layers and the second semiconductor layer 26, which is relatively close to the surface of the second semiconductor layer 26, the greater the amount of emitted light is obtained. In this embodiment, in consideration of this phenomenon, technical parts 27b and 27 are formed on the semiconductor layer 29 exposed in the openings 28Eh to 28d.
c is arranged, the amount of emitted light is further increased based on the above-mentioned principle.

Effects of the Invention As described above, according to the invention of claim 1, the electrode formed on the surface of the semiconductor substrate on which the semiconductor portion is formed has a size that covers the semiconductor portion, and has a predetermined size. The shape is chosen to have a through hole of the same size. The light thus generated is output only from the through hole, and a result similar to that obtained by reducing the light emitting area can be obtained. According to the invention of claim 2, it is thereby possible to obtain a smaller light emitting region when forming a semiconductor portion by diffusion technology without unnecessarily improving the processing accuracy of a mask used for diffusion. For example, the semiconductor portions of the semiconductor substrate are selected to have a shape in which the depth of their bonding surfaces from the surface of the semiconductor substrate has a plurality of levels. It has been discovered that when the amount of current applied is the same, the light output level of a semiconductor photoelectric conversion device increases as the depth of the contact surface becomes relatively smaller.Therefore, the above configuration improves the photoelectric conversion efficiency. can do.

[Brief explanation of drawings]

FIG. 1 is a plan view of an LED 11 according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the section line 1I21 - ■, and FIG. 3 is a section along the section line ■--■ in FIG. 1. 4 is a plan view of the gutter 12 to the optical printer, FIG. 5 is a plan view explaining the movement of this embodiment, and FIG. 6 is a sectional view of the ED 31 of another embodiment of the present invention. 7 (21 is a diagram explaining the characteristics of the LED 31, FIG. 8 is a sectional view explaining the principle of this embodiment, FIGS. 9 and 10 are diagrams explaining the effect of this embodiment, FIG. 11 is a diagram explaining a comparative example of this embodiment, and FIG.
The figure is a cross-sectional view of a typical conventional LED L, and Figure 13 is a sectional view of a typical conventional LED L.
FIG. 3 is a diagram illustrating characteristics of the amount of light emitted by EDI. 11...LED, 12...Optical printer head, 13
...Substrate, 14...Common lead wire, 17...Individual electrode, 17a...Connection part, 171), 17c=...
Branch portion, 17d... Through hole, 25... First semiconductor layer, 26...
- Second semiconductor layer, 27... mask layer, 28... opening, two... semiconductor layer, 30... light emitting region, 31...
・LIED agent Patent attorney Kei Saikyo Part of the drawings: (Changes to the contents - □ in Figure 1) Figure 2<14 Figure 3 Figure 5 Figure 6FA Figure 7] Hitomi Totoshi Figure 9 Figure 10 Distance reM=;11
figure,/ ? Figure 12, Figure 13” Written amendment to the procedure for making the amendment (method) 1. Indication of the case Patent application Hei 1-126882 2. Name of the invention Semiconductor photoelectric conversion device 3. rFlj application with the person making the amendment Person Address Name (663) Kyocera Corporation Representative 4, Agent Address 1-13-38 Nishihonmachi, Nishi-ku, Osaka Shinkobu Building Country Equipment EXO525-5985rNTAPT J
International FAX (06) 538-0247 (representative) 6, drawings to be amended 7, content of amendments: engraving of the drawings (no change in content). that's all

Claims (2)

[Claims] (1) Semiconductor photoelectric conversion in which a semiconductor portion of one conductivity type is formed in a predetermined light emitting region of a semiconductor substrate of one conductivity type, electrodes are formed on both surfaces of the semiconductor substrate, and electricity is passed between the electrodes to obtain light emission output. In the device, the electrode formed on the surface of the semiconductor substrate on which the semiconductor portion is formed is selected to have a size that covers the semiconductor portion and a shape having a through hole of a predetermined size. Semiconductor photoelectric conversion device. (2) The semiconductor photoelectric conversion device according to claim 1, wherein the semiconductor portion of the semiconductor substrate is formed in such a shape that the depth of their bonding surfaces from the surface of the semiconductor substrate has a plurality of levels.