JPS631079A - Semiconductor light-receiving element and manufacture thereof - Google Patents

Abstract

PURPOSE:To form a PIN photodiode having high performance by forming and growing a light absorption layer in low concentration onto a substrate in high impurity concentration, selectively introducing an impurity to shape a P-type region and depleting the whole regions by reverse bias voltage. CONSTITUTION:An N<->-InP buffer layer 2 in low concentration, an N<->-In GaAs light absorption layer 3 in low impurity concentration, an N-InP layer 4' functioning as a window layer and an N<->-InP layer 4'' in low concentration are grown continuously onto an N<+>-InP substrate 1 in high impurity concentration through a vapor growth technique. An impurity is introduced selectively, using an SiNx film formed through plasma CVD as a mask to shape a P-type region 5. The whole regions are depleted by predetermined reverse bias voltage because the impurity concentration of the region 3 is low at that time. When beams are projected to an element, incident beams are absorbed approximately in the region 3, and optical pumping carriers are col lected to a junction 10 by a drift field. Accordingly, optical pumping carriers are collected approximately without recombination.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor light-receiving device, and particularly to one that has sensitivity at a low bias voltage, or even zero bias voltage, and has a small dark current.

[Conventional technology]

In general, in photodiodes, in order to achieve high sensitivity and high speed response, it is desirable to operate with a low bias voltage in the 6-wire structure that uses a PIN type structure, so the first layer has a high resistance (high purity). , is designed to become a depletion layer at low voltage. By the way, in photodiodes using compound semiconductors such as Inp-based and GaSb-based, a semiconductor with a narrow bandgap (Ell) is used in one layer that absorbs light to extend the wavelength limit of sensitivity toward longer wavelengths. A measure to reduce dark current by forming a junction formed by selectively introducing impurities within a material with a large forbidden band width (E#) or near the interface with a material with a small forbidden band width through it. (Unexamined Japanese Patent Publication No. 53-16593)
) However, in a compound semiconductor PIN type photodiode having such a hetero-interface made of materials having different bandgap widths and in which both materials have low impurity concentrations, there are problems as described below.

In order to operate at high speed with a low bias voltage, the impurity concentration of at least one layer (substance with small CEx) is set to be on the order of 10 taaw-' or less, and the entire layer is designed to be a depletion layer. In the conventional method, the impurity concentration of a material with a large Ew with which a junction is formed is designed to be about the same as that of a single layer in order to increase the reverse dielectric strength and obtain stable operation. However, Applied Physics Letter 43.6 (1983)
Pages 594 to 596 (Appl, Phys, Lett
, 43, 6 (1983) pp594-596), when the impurity level is 10za
-3, diffusion occurs at an extremely fast diffusion rate.
Problems have arisen in that it becomes difficult to control the junction, and that lateral diffusion along the interface occurs depending on the lattice mismatch of the heterointerface, resulting in a substantial junction.

These phenomena increase the capacitance of the device and degrade high-speed response as a result of the junction substantially widening.
This increases dark current and causes deterioration of the S/N ratio. In addition, because the controllability of diffusion deteriorates, if the junction is formed far from a material with a small E□, the depletion layer will not reach one of the eight layers unless the reverse bias voltage is increased. Sensitivity decreases. In particular, in compound semiconductors that have a hetero interface, there is an energy gap between the hetero layers and a short carrier lifetime, so if the depletion layer extending from the junction does not reach one layer (8 layers of material) that becomes the light absorption layer. , the sensitivity is significantly reduced. On the other hand, if the junction is formed deep within a substance with a small Recombination occurs before the reaction occurs, reducing sensitivity.

Therefore, it becomes difficult to realize an element with low bias voltage, high sensitivity, and high speed response.

In addition, in conventional InGaAs PIN photodiodes, a pn junction is formed using selective diffusion technology in the InGaAs light absorption layer with a low impurity concentration, as was done with Thomson C3F's POULAIN, and the bias voltage of the device is (Electronics Letter Vol. 21, pp. 441-2, 1)
985 (Electronics Letters,
VoQ, 21 (1985) 441-442)).

Furthermore, as an example of optical technology using InGaAs for the window layer, B
The only example is the avalanche photodiode by F. Capasso et al.
Taking advantage of the small energy difference of 0.2 eV in the valence band between GaAs and I n A Q A s, we aim to effectively move photoexcited carriers to the avalanche multiplication region by The purpose was to reduce dark current, and it was not actively used to reduce dark current.

Further, in recent years, optical communication and information processing technology using light with a wavelength in the 1 to 1.6 μm band has made remarkable progress.

As the light receiving element in this case, a compound semiconductor element mainly composed of Inp+ InGaAs is expected.

In particular, as a light receiving element for monitoring the excavation state of a semiconductor laser, it operates without a bias voltage.

It is desirable to have an element with a low dark current and a low capacitance.
985) pp. 441-442) and shown in FIG.
After growing a A s into a double heterostructure, I n G a is grown from above the upper InP layer through the upper InPM.
By diffusing impurities into the A s layer, I n G
It was known that this could be obtained by locating the PN junction within the a As layer. However, no consideration was given to how to position the PN junction at a predetermined position in InGaAs 77) with good reproducibility.

Furthermore, InPM and InG with relatively low impurity concentrations
When thermal diffusion of impurities is performed in the vertical direction to the heterojunction of the aAs layer, there is a phenomenon in which lateral diffusion occurs along the junction surface when the impurity reaches the heterojunction surface. For this reason, planar PIN photodiodes based on selective thermal diffusion using a diffusion mask have had problems with increased capacitance and dark current due to lateral diffusion at the heterojunction surface. In the above-mentioned literature, a mesa type structure is adopted to avoid this problem, but a countermeasure for a planar type with excellent productivity has not been known so far.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology does not take into account the control of junction formation in consideration of the hetero-interface of the amount of material with a low impurity concentration, nor the undesirable diffusion depending on the interface.

There have been problems with deterioration of element performance, such as a decrease in sensitivity, deterioration in response speed, and fluctuations in the appropriate operating bias voltage.

In addition, it is known that when the impurity concentration is reduced to lXl0"cm-3, the diffusion rate increases, making it difficult to control the pn junction front. s When formed within the light absorption layer,
As the two layers in the InGaAs layer become thicker, incident light is absorbed, resulting in a decrease in quantum efficiency. The above-mentioned conventional technology has problems in that the controllability of the diffusion front within InGaAs is poor, and the two layers become too thick, resulting in a decrease in quantum efficiency.

Furthermore, conventional long-wavelength photodiodes use a vapor phase growth method that allows for highly purified crystals, and use I as a window layer/light absorption layer.
It adopted an nP/InGaAs structure. However, from the growth of the I n Ga As layer, the I
When moving on to nPM growth, due to the influence of residual arsenic gas, I n
There was a problem in that a modified layer with an undefined composition was likely to be formed between the GaAs layer and the InPM. This modified layer increases the r6 current of the photodiode as a generated current.

In addition, in the above-mentioned conventional technology, no consideration is given to the position controllability of the PN junction surface and the suppression of lateral diffusion at the heterojunction surface, and the quantum efficiency is reduced due to the PN junction reaching deep into the InGaAs layer. There have been problems such as an increase in capacitance and dark current caused by a decrease in the junction area and an abnormal increase in the junction area at the heterojunction surface.6 The purpose of the present invention is to consider the impurity concentration, the interface layer, and the position of the main junction. By doing so, the object is to realize a stable semiconductor light-receiving element with low bias voltage, or even zero bias voltage, high sensitivity, high speed, and low dark current.

Means for Solving Problem C] The above object is to devise the impurity concentration distribution constituting the photodiode, as shown in FIGS. 1 to 4.

This allows the joint position to be controlled and achieves high performance.

That is, Eg in which a junction is formed by selectively introducing impurities.
The material 4 with a high impurity concentration consists of a region 4' with a low impurity concentration and a thin region 4' with a relatively high impurity concentration. In a zero impurity concentration structure in which the material 3 with a low impurity concentration and low El that acts as a light absorption layer is in contact with the region 4', when an impurity of the other conductivity type is introduced from the surface of the region 4', the junction is formed. It is formed beyond the region 41, which has a fast diffusion coefficient, and within the region 4', which has a high impurity concentration and has a slow diffusion rate.

In order to operate at a low bias voltage in this state, it is necessary that the depletion layer extending from the junction reaches the boundary between regions 4' and 3, at least due to the built-in potential. In this case, sensitivity can be obtained with zero bias voltage, and the externally applied voltage is effectively used to make region 3 a depletion layer.

- On the other hand, if the depletion layer does not reach the boundary, when the depletion layer first extends to the boundary due to an externally applied voltage, the photoexcited carriers generated in region 3 are collected at the junction and contribute to the photocurrent. It becomes like this.

The diffusion potential of compound semiconductors with relatively large Eo, such as InP and GaAs, can be considered to be approximately 1V.
In order for at least 4a to become a depletion layer at the diffusion potential, the region 4'
The relationship between the impurity concentration N and the thickness d is given by the following equation.

E N-d2<□ (1) where q: electron charge element, E: dielectric constant For example, in the case of InP, the above equation becomes as follows.

N<1.4 X 1 0 56/d2
(2) From the literature and experiments mentioned above,
In order to control the junction position and prevent lateral diffusion at the hetero interface, the impurity concentration should be at least I x 1018cxr-”
The above was found to be effective (concentrations below this have no significant effect on diffusion, etc.).For this purpose, the thickness must be approximately 0.3 μm or less from equation (2). It becomes necessary. Considering the accuracy of controlling the bonding position by the region 4', the thickness needs to be 0.1 μm. In this case, the impurity concentration will be approximately I x 1017 tym-3 or less from equation (2). These results have been experimentally verified, and it has been found that it is appropriate to set the impurity level in the 4' layer to 101B-1017 pieces-8 and a thickness of 0.1 to 0.3 μm. Do you get it. As can be seen from equation (1), there is not much difference in dielectric constant between semiconductors, so this relationship can also be applied to other conductors.

Furthermore, the above purpose is to insert a T nAQAs layer between the InGaAs light absorption layer and the InP window layer,
This can also be achieved by forming a pn junction within.

In addition, the above purpose is to configure the InGaAs light absorption layer with two layers, a layer with a relatively high impurity concentration and a layer with a low impurity concentration, and to form a pn junction in the light absorption layer with a relatively high impurity concentration. This is achieved by forming.

Further, the above purpose is to form an InP layer with a slightly higher impurity concentration below the upper InP layer, and to
The impurity concentration is relatively high on the top of the FIAs layer.
nGaas! ? 4, and by forming impurity diffusion at the top or inside the TnGaAs layer having a high impurity concentration.

[Effect]

In FIG. 1, a region 4' made of a material with a large Ex and having a relatively high impurity concentration operates to position the pn junction within the region 4'. Further, since a junction is formed within 4', abnormal diffusion can be prevented along the hetero interface between regions 4 and 3.

These technical means make it possible to stably control the position of the junction and prevent abnormal diffusion along the hetero interface, making it possible to obtain a photodiode with uniform and excellent characteristics with good reproducibility.

In the InGaAs layer, which has a relatively high impurity concentration, the diffusion rate is slow, and there is a controllability within the InGaAs layer.
A pn junction can be formed. Therefore p −I
Since the thickness of the nGaAs layer can be made thinner, the bias voltage O can be reduced without reducing the quantum efficiency.
■It becomes possible to operate. Further, when a bias voltage is applied, the depletion layer extends to InGaAs having a low impurity concentration, and the depletion layer can be greatly extended even with a low bias voltage. Therefore, it is possible to keep the capacitance small with a low bias voltage, and it is also possible to realize a high-speed response limited by the CR time constant.

In the vapor phase growth method, I
When moving on to the growth of nAl2As#, since the arsenic gas is not turned off, a modified layer due to residual arsenic gas does not occur.
When moving from the growth of A s and Q to the InP layer, the influence of residual arsenic remains, but since the pn junction is formed within the InARAs layer, the heterointerface of the InGaAs layer InP is affected by dark current degradation as a photodiode. therefore does not affect.

According to the present invention, a photodiode with low dark current can be realized.

Furthermore, since the impurity concentration of the crystal growth layer is low, the capacitance can be kept low, and high-speed response controlled by the CR time constant can also be realized.

Furthermore, when an InP-based semiconductor is used, the upper InP
The InP layer with a slightly high impurity concentration formed at the bottom of the layer is
6-way serves to alleviate and prevent abnormal lateral diffusion caused by stress at the interface between the upper InP layer and the InGaAs layer.

In r nGaAsM, which has a relatively high impurity concentration and is formed at a relatively upper portion of the I n Ga As layer, the diffusion rate is slow, so it is easy to stop the PN junction at the upper end or inside the layer.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

Example 1 This example describes the case where an InP-based material is used, but the essence of the present invention does not change even when other compound semiconductors such as other GaSb-based materials are used.

On the n+-■nP substrate 1 with a high impurity concentration, continuously low-concentration n--
InP buffer layer 2. n--InGaA with low impurity concentration
s light absorption layer 3. Grow <n-InPH4' and a low concentration n-1nP layer 4' to serve as a window layer. Region 3 has an impurity concentration of 1 x 10"Ql-8 and a thickness of 2.5 pm. The 4' layer and 4' layer each have an impurity concentration of 2 x
IQ “cxs-”.

I x 1018cm-”, 7m [length 0.2μm,
It is 1.8 μm. S formed by plasma CVD
Using the xN film as a mask, impurities are selectively introduced to form a p-type head region 5. The optical end of the region 5 is in contact with or inside the region 4'. In forming the p-type impurity region, thermal diffusion of Zn, Cd, etc., or ion implantation of Be, Mg, etc. is used. The tip of the pn junction is indicated by 10. Next, as a passivation film, S
xNx/PSG/Si○2 three-layer film 6, full-layer film 6, and SiN layer 7 were used as the antireflection film. 8. T i / P d / Au vapor deposited film on the p-type electrode. nJ
T161! An AuGeNi/P d /Au vapor deposited film 9 was formed on the pole.

In the present invention, due to the diffusion potential, the edge of the depletion layer from the junction is In
The depletion layer reaches the GaAs region 3, and by applying a bias voltage, the depletion layer extends to the entire region 3. Area 3
Because the impurity concentration is low.

With a reverse bias of 5V, the entire region becomes a depletion layer. When light is incident on this element, most of the incident light is absorbed within region 3,
Photoexcited carriers are collected at junction 10 by the drift electric field. For this reason, photoexcited carriers are collected with almost no recombination, resulting in high quantum efficiency, and since they migrate by drift, high-speed response is possible. 1.55μm
Experiments using a semiconductor laser showed a quantum efficiency of 90%,
Pulse rise and fall times of less than ins were obtained.

According to this embodiment, the junction is formed in a thin region with a relatively high impurity concentration, and the influence of the hetero interface can be reduced, so that the dark current is reduced. Furthermore, since the depletion layer reaches the light absorption region with no bias voltage, it has high sensitivity even with zero bias. Furthermore, since the light absorption region becomes a depletion layer at a low bias voltage, a voltage that is compatible with IC power supplies such as TTL (
For example, 5V), high-speed response can be achieved. Furthermore, since a substance with a low impurity concentration and a large E+t is formed on the surface (region 4'), the withstand voltage in the reverse direction becomes large.

Example 2 This will be explained with reference to FIG.

FIG. 2 is a longitudinal cross-sectional view of an InGaAs PIN photodiode.

An n--InP buffer layer 2 is formed on an n-type 1nP substrate (S-doped) 1. n--InGaAsnGaAs light absorption layer nGa
As layer 14. The n--InP window layer 15 is formed by MOCVD (or chloride VPE).

Continuous growth is performed using hydride VPE method, MBE method). The pn junction 16 is formed in the n-InGaAs light absorption layer by selective thermal diffusion of Zn or Cd or ion implantation of Be or Mg. n to prevent the diffusion constant from becoming large.
-The impurity concentration of the I n Ga As layer is IXIO
lGam-8, and the controllability of the diffusion front of the pn junction is set to ±0.1 μm.

The passivation film 17 is Si○x/PSG/S
Adopts 3Mm structure of i N x, S i N, / I
The nP interface level is suppressed to less than 5 × 10” country-1,
This prevents dark current deterioration due to surface leakage current.

The antireflection film 18 is made of Si used as a passivation film.
By adopting an Nx film and optimizing the film thickness to the 1.5 μm band, the reflectance can be suppressed to z or higher.

The p-type ohmic electrode is A u / P t / T i
19. The n-type ohmic electrode is A u / P d /
Good ohmic characteristics are achieved by using A u G s N 1110.

The incident light is absorbed by the InGaAs light absorption layer. Light absorption in the p-InGaAs layer results in loss a I
Since the absorption coefficient of nGaAs is 10'ay+-',
If the thickness is within 0.1 μm, the loss will be about 10%, and there are almost no other loss factors, so 90%
% or more quantum efficiency can be expected. Also, InGaAs
The forbidden band width of InP (1,35ev) is o, 75eV.
Since the dark current is smaller than that of the InP layer, the dark current is slightly larger than that of the pn junction in the InP layer, but the bias voltage of 10V
This can be suppressed to a practical level of about 1 nA.

Since the impurity concentration of the n-I n Ga As layer is low, the depletion layer is greatly extended at a low bias voltage, and a capacitance of about 0.5 PF can be expected at 1 o.

The high-speed response of the photodiode is limited by the CR time constant, so if the load resistance is 50Ω, the CR time constant is 25P.
S, and high-speed response of 10 GHz or more can be expected.

Example 3 This will be explained with reference to FIG.

Figure 3 shows I n P / I n A n A s /
FIG. 2 is a longitudinal cross-sectional view of an InGaA 5PIN photodiode.

On n-type InP substrate 1 (S or Sn doped), MO
By CVD method (or VPE method, MBE method), n--
InP buffer layer 2. n--InGaAsnGaAs light absorption layer nAQAs window layer 24. An InB" window layer 25 is continuously grown. The impurity concentration of the n-layer is lXl0I" -8. Next, selective thermal diffusion of Zn was carried out using the SiN film formed by plasma CVD method as a diffusion mask, and p+
-InB layer.

A p+ InAaAs layer 26 is formed. Next, SiNx by plasma CVD method and SiOx by thermal CVD method.
/ After passivating with the three-layer structure 7 of PSG, 5iOz/PSG is removed and S i N x
An antireflection film 8 is formed.

Finally, p-type ohmic electrode (A u / P t /
T i )29, n-type ohmic electrode (Au/Pd/A
uGeN1) 210 is formed.

Light incident on the photodiode is absorbed by the InGaAs layer, which is biased and becomes a depletion layer, and carriers are generated. The generated carriers drift and advance within the depletion layer, reach the pn junction, and are taken out from the electrode as a photocurrent to an external circuit.

The photodiode of this example has good characteristics of low dark current. If the thickness of InGaAs is about 53 μm, the internal quantum efficiency will be close to 100%. In addition, the non-reflective coating of the SiNx film can suppress surface reflection to 1% or less, so an external quantum efficiency of 90% can be expected. Furthermore, since the impurity concentration of the crystal growth layer is as low as 1X10130-3, a low capacitance of 0.5 pF can be achieved at IOV. In addition, the dark current is also I n A Q A s / I n Ga
Since it is possible to prevent the dark current from deteriorating at the A s hetero interface, it is possible to suppress the dark current to 1 nA or less at 10V. Furthermore, the high frequency characteristics are usually band controlled by the CR time constant, and high-speed operation of 10 GHz or higher is possible due to the low capacity.

As described above, it can be seen that this example exhibits good electrical and optical characteristics with low voltage operation.

In addition, since the impurity content of the A Q I n A s layer is relatively high, a pn junction can be formed with an accuracy of ±0.2 μm, and a high yield can be expected when photodiodes are industrially produced.

Example 4 This will be explained with reference to FIG. Figure 3 shows InP/InG
FIG. 2 is a longitudinal cross-sectional view of an a As planar PIN photodiode.

(n--In on 1+ InP substrate (S-doped) 1
P buffer M2. n--I nGaAs light absorption layer 3. n
-InGaAs layer 34. n-1nP window layer 35. n--I
The nP window layer 36 was continuously grown by MOCVD. The thickness of each layer and the impurity concentration are 2; 0.5 pm, I
X 10”am-8,3; 2 μm.

lXl0"m-', 34; 0.4pm, 2xlO1
6cts-”, 35; 0.2μm, 2X1016a
n-'', 36; 3 pm, I x 10''cm-'
It is. Next, a 5iOz/PSG film was placed on top of 36.
D, and a diffusion mask pattern was formed by photolithography.

The diffusion diameter is 100 μmφ. Next, ZnPz was thermally diffused at 550°C using a closed tube method, and the PN junction surface was heated to 320t.
p-type 1 n P 7 l p p-type InGaAs7-
2 was formed. The passivation film 38 is made of SiOx/
PSG/SiNx three-layer structure film 2 anti-reflection film 39 is SiN
It is x. The p-type electrode 310 has A u /P t /
Ti and Au/P d/A for the n-type electrode 311.
uGeNi was used.

After device fabrication, P is etched using EB IC method and stain etch method.
When I checked the N junction position, I found that PNN junction Freon 8 was placed n
- It was located at the upper end or inside the InGaAs layer 34 with good reproducibility, and no abnormal lateral diffusion was observed along the bonding surfaces between the layers 36 and 35 and 35 and 34.

The obtained device had a quantum efficiency of 80% without a bias voltage, and had a high performance with a junction capacitance of about 2 pF.

〔Effect of the invention〕

According to the present invention, the structure is such that a material with a relatively high impurity concentration and a large bandgap width is in contact with a material with a small bandgap width and a low degree of impurity tA, and the material is formed in a region with a large bandgap width. Since the depletion layer extends from the junction to the region where the forbidden band width is small at the diffusion potential, the following effects are produced.

(1) The bonding position can be formed near the light-absorbing head region with good reproducibility.

(2) The influence of abnormal impurity diffusion due to the influence of hetero-interfaces can be reduced.

(3)! ! High insensitivity can be achieved with bias or low bias.

(4) The junction is located in a region where E5 is large, and the influence of the hetero interface is eliminated, so the dark current becomes small.

Further, according to the present invention, since the modified layer due to residual arsenic gas at the hetero interface between the light absorbing layer and the window layer can be removed, there is an effect that deterioration of dark current due to lattice defects can be suppressed to a low level.

Further, according to the present invention, a high-performance (low capacitance, low dark current, high quantum efficiency) planar PIN photodiode that has sensitivity at zero bias voltage can be produced with good reproducibility.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of an element showing Example 1, FIG. 2 is a cross-sectional view of InP/InAlAs/InGaAs of Example 2, and FIG. 3 is a cross-sectional view of an element using InGa'As of Example 3. FIG. 4 is a sectional view of an element shown in Example 4, and FIG. 5 is a sectional view of a conventional light receiving element. 1-n+ -I nP substrate, 2-n--I nP buffer layer, 3-n--I nGaAs light absorption layer, 4'...
n-InP thin layer, 4'-n--I nP window layer, 5...
・p-InP diffusion layer, 6...passivation layer, 7
...Anti-reflection film, 8...p-side electrode, 9...n-side electrode, 10-p-n junction, 14-n--I nAffA
sg layer, 15-n--I n P window layer, 16-p-
I n P layer. p −I n A Q A s M (Z n diffusion),
1 '7-3 iOz/PSG/SiNx (2000
72,000 people/2,000 people), 18-8iNx (
1900 people), 19...p-type ohmic electrode A u
/ P t / T i (1.0 μm10.1 μm1
0.1 μm), 110'''nn type ohmic electrode Au/Pd/AuGeNi(
1.0μm10. tumlo, 1 μm),
24...n-1nGaAs light absorption layer, 25-n--
InP window layer, 26-p-InP, p-InG, aAs layer (selective thermal diffusion of Zn or Cd), 27...passivation film Si○z / P S G / S x N
x, 28...Anti-reflection film (S x N x t
1900 people), 29...P-type ohmic electrode (Au/
Pt/Ti), 210” n-type ohmic electrode (A u
/ P d / AuGeN1), 34 = −n −
InGaAs light absorption layer, 35-n-In
P window layer, 36-n--I n P window layer, 37-p-I
nP, 37-p-I n Ga As, 38 ・
...Passivation film, 39...Antireflection film, 31
0...p-type electrode, 311...n-type electrode, 320...
・PN junction surface. ”＼

Claims (1)

[Claims] 1. A semiconductor light-receiving device comprising a semiconductor laminated structure including a main junction having a light-receiving device function on a substrate, which has one conductivity type, has a large forbidden band width, and emits light. Between the semiconductor layer that absorbs (light absorption layer) and the semiconductor layer (window layer) that transmits light with a small forbidden band width, one or more intermediate layers are provided whose impurity concentration is higher than that of the light absorption layer and the window layer. A semiconductor light-receiving element comprising the intermediate layer. 2. A patent in which the intermediate layer is a region of the window layer in which the impurity concentration is increased in the light absorption layer side portion, and/or a region in which the impurity concentration in the window layer side portion of the absorption layer is increased. A semiconductor light-receiving device according to claim 1. 3. The semiconductor light-receiving device according to claim 1, wherein the window layer and the light absorption layer are made of InP, and the intermediate layer is made of InAlAs. 4. The window layer is InP, and the intermediate layer is InAl.
The semiconductor light receiving element according to claim 1, which is made of As. 5. The window layer is InP, the light absorption layer is InGaAs, the intermediate layer is a region of the light absorption layer with a high impurity concentration, and the junction is within the intermediate layer, claim 1. The semiconductor photodetector described above. 6. The semiconductor light-receiving device according to claim 1, wherein the main junction is formed within the intermediate layer. 7. The impurity concentration of the intermediate layer is 1×10^1^6 to 1×
10^1^7cm^3, and this thickness is 0.1 to 0.3μ
The semiconductor light-receiving device according to claim 1, which is m. 8. The impurity concentration of the intermediate layer is 1×10^1^6 cm^
-^3 or more, and the impurity concentration of the window layer and the light absorption layer is 10^1^6 cm^-^1 or less. 9. The impurity concentration of the intermediate layer is 5×10^1^6~5×
The semiconductor light-receiving element according to claim 1, which has a diameter of 10^1^6 cm^-^3 and a thickness of 0.5 μm or less. 10. A method for manufacturing a semiconductor light-receiving device comprising steps of forming a semiconductor layer structure including a main junction having a light-receiving device function on a substrate, which has one conductivity type, has a large forbidden band width, and does not emit light. The process of forming a semiconductor layer that absorbs light (light absorption layer) and the semiconductor layer that has a small forbidden band width and transmits light (window layer)
1. A method for manufacturing a semiconductor light-receiving device, comprising the step of forming an intermediate layer between the steps of forming the semiconductor light-receiving device. 11. The method of manufacturing a semiconductor light receiving element according to claim 10, wherein the main junction is formed in an intermediate layer. 12. The method of manufacturing a semiconductor light receiving element according to claim 10, wherein the main junction is formed by thermal diffusion of Zn.