Semiconductor photodetector

Abstract

To provide a semiconductor light-receiving element having a long absorption edge wavelength.SOLUTION: A semiconductor light-receiving element comprises a first group III-V semiconductor layer of a first conductivity type, a second group III-V semiconductor layer of a second conductivity type, and a light-receiving layer provided between the first group III-V semiconductor layer and the second group III-V semiconductor layer in a first direction. The light-receiving layer includes a plurality of unit structures laminated in the first direction. Each of the plurality of unit structures includes a gallium arsenide layer and an indium arsenide layer, and a gallium arsenide antimony layer. The gallium arsenide layer and the indium arsenide layer have a thickness smaller than a thickness of the gallium arsenide antimony layer.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a semiconductor light receiving element. [Background technology]

[0002] Non-Patent Document 1 discloses a photodiode with an absorption layer provided on an n-type indium phosphide (InP) substrate. The absorption layer has 150 pairs of type II superlattices. Each pair includes a gallium indium arsenide (GaInAs) layer and a gallium arsenide antimonide (GaAsSb) layer. This photodiode achieves a cutoff wavelength (absorption edge wavelength) of 2.39 μm.

[0003] Non-Patent Document 2 discloses a photodiode having an absorption layer provided on an n-type InP substrate. The absorption layer has 100 pairs of type II superlattices. Each pair includes a GaInAs layer and a GaAsSb layer. The absorption layer has a strain-compensated quantum well structure. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Rubin Sidhu, et al, "ALong-Wavelength Photodiode on InP Using Lattice-Matched GaInAs-GaAsSb Type-IIQuantum Wells" IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 17, NO. 12, DECEMBER 2005, p.2715-2717 [Non-patent document 2] Baile Chen, et al, "SWIR / MWIRInP-Based pin Photodiodes with InGaAs / GaAsSb Type-II Quantum Wells" IEEEJOURNAL OF QUANTUM ELECTRONICS, VOL. 47, NO. 9, SEPTEMBER 2011, p.1244-1250 Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure provides a semiconductor light-receiving element having a long absorption edge wavelength. [Means for solving the problem]

[0006] A semiconductor light-receiving element according to one aspect of the present disclosure includes a first III-V semiconductor layer of a first conductivity type, a second III-V semiconductor layer of a second conductivity type, and a light-receiving layer provided in a first direction between the first III-V semiconductor layer and the second III-V semiconductor layer, the light-receiving layer including a plurality of unit structures stacked in the first direction, each of the plurality of unit structures including a gallium arsenide layer, an indium arsenide layer, and a gallium arsenide antimony layer, the gallium arsenide layer and the indium arsenide layer having a thickness smaller than a thickness of the gallium arsenide antimony layer. [Effects of the Invention]

[0007] According to the present disclosure, a semiconductor light-receiving element having a long absorption edge wavelength is provided. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view schematically showing a semiconductor light-receiving element according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view schematically showing a light-receiving layer included in the semiconductor light-receiving element of FIG. [Figure 3] FIG. 3 is a cross-sectional view schematically showing a unit structure included in the absorption layer of FIG. [Figure 4] FIG. 4 is a graph showing an example of an energy band diagram in the absorption layer of the semiconductor light receiving element according to the first experiment. [Figure 5] FIG. 5 is a graph showing an example of an energy band diagram in the absorption layer of the semiconductor light receiving element according to the second experiment. [Figure 6] FIG. 6 is a graph showing an example of the spectrum of the optical absorption coefficient obtained in the third and fourth experiments. [Figure 7] FIG. 7 is a cross-sectional view schematically showing a modified example of the unit structure included in the absorption layer of FIG. [Figure 8] FIG. 8 is a graph showing an example of the spectrum of the optical absorption coefficient obtained in the fourth and fifth experiments. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described.

[0010] (1) A semiconductor light-receiving element includes a first III-V semiconductor layer of a first conductivity type, a second III-V semiconductor layer of a second conductivity type, and a light-receiving layer provided between the first III-V semiconductor layer and the second III-V semiconductor layer in a first direction, the light-receiving layer including a plurality of unit structures stacked in the first direction, each of the plurality of unit structures including a gallium arsenide layer, an indium arsenide layer, and a gallium arsenide antimony layer, the gallium arsenide layer and the indium arsenide layer having a thickness smaller than a thickness of the gallium arsenide antimony layer.

[0011] The absorption edge wavelength of the semiconductor optical device described above can be made longer than when the electron well layer in each unit structure is made of only GaInAs layers. This is thought to be because the intrinsic energy of the wave function of the conduction band in the electron well layer is different.

[0012] (2) In the above (1), each of the plurality of unit structures may further include a gallium indium arsenide layer, and the gallium arsenide layer and the indium arsenide layer may be disposed between the gallium indium arsenide layer and the gallium arsenide antimony layer in the first direction. In this case, by adjusting the gallium composition in the gallium indium arsenide layer, lattice strain caused by the gallium arsenide layer and the indium arsenide layer can be canceled. Therefore, the average amount of strain in the electron well layer can be reduced.

[0013] (3) In the above (2), the gallium indium arsenide layer may have a gallium composition of 0.4 to 0.55.

[0014] (4) In the above (2) or (3), the thickness of the gallium indium arsenide layer may be 0.8 to 2.1 nm.

[0015] (5) In any one of the above (1) to (4), the thickness of the gallium arsenide layer may be 0.2 to 1.5 nm.

[0016] (6) In any one of the above (1) to (5), the thickness of the indium arsenide layer may be 0.2 to 1.6 nm.

[0017] (7) In any one of the above (1) to (6), the thickness of the gallium arsenide antimonide layer may be 2.5 to 6.3 nm.

[0018] (8) In any one of the above (1) to (7), the number of pairs including the gallium arsenide layer and the indium arsenide layer in each of the plurality of unit structures may be 1 to 10.

[0019] (9) In any one of the above (1) to (8), the arsenic composition of the gallium arsenide antimonide layer may be 0.45 to 0.6.

[0020] (10) In any one of (1) to (9) above, the semiconductor light receiving element may further include an indium phosphide substrate, and in the first direction, the first III-V semiconductor layer may be provided between the indium phosphide substrate and the light receiving layer.

[0021] [Details of the embodiments of the present disclosure] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or equivalent elements are designated by the same reference numerals, and redundant description will be omitted.

[0022] FIG. 1 is a cross-sectional view schematically illustrating a semiconductor light-receiving element according to one embodiment. The semiconductor light-receiving element 10 illustrated in FIG. 1 includes a first III-V semiconductor layer 12 of a first conductivity type, a second III-V semiconductor layer 14 of a second conductivity type, and a light-receiving layer 16. The first conductivity type is, for example, n-type. The second conductivity type is opposite to the first conductivity type. The second conductivity type is, for example, p-type. The light-receiving layer 16 is undoped. The semiconductor light-receiving element 10 is, for example, a photodiode. The light-receiving layer 16 is disposed between the first III-V semiconductor layer 12 and the second III-V semiconductor layer 14 in a first direction D1. The first direction D1 is the thickness direction of the light-receiving layer 16. The first direction D1 may be a direction from the first III-V semiconductor layer 12 toward the second III-V semiconductor layer 14. The first direction D1 may be a crystal growth direction. Alternatively, the first direction D1 may be a direction from the second III-V semiconductor layer 14 toward the first III-V semiconductor layer 12. The first direction D1 may be a direction opposite to the crystal growth direction.

[0023] The first III-V semiconductor layer 12 may be an indium phosphide (InP) layer. The dopant concentration in the first III-V semiconductor layer 12 is 1×10 23 From 1×10 24 m -3 The first III-V semiconductor layer 12 may have a thickness of 0.1 to 1 μm. Examples of n-type dopants include silicon (Si), tellurium (Te), and tin (Sn).

[0024] The second III-V semiconductor layer 14 may be an InP layer. The dopant concentration in the second III-V semiconductor layer 14 is 1×10 23 From 1×10 24 m -3 The second III-V semiconductor layer 14 may have a thickness of 0.1 to 1 μm. Examples of p-type dopants include zinc (Zn) and beryllium (Be).

[0025] The semiconductor light-receiving device 10 may further include a substrate 18. The substrate 18 may be a III-V semiconductor substrate such as an InP substrate. The substrate 18 may be a semi-insulating substrate. The first III-V semiconductor layer 12 may be provided between the substrate 18 and the light-receiving layer 16 in the first direction D1. The first III-V semiconductor layer 12 may be provided on a primary surface of the substrate 18. The primary surface of the substrate 18 may be a (100) plane. The primary surface of the substrate 18 may be perpendicular to the first direction D1.

[0026] The semiconductor light receiving element 10 may further include a first conductivity type III-V semiconductor layer 20. The III-V semiconductor layer 20 is provided between the first III-V semiconductor layer 12 and the substrate 18 in the first direction D1. The III-V semiconductor layer 20 may be a contact layer. The III-V semiconductor layer 20 may be an InP layer. An electrode 30 may be connected to the III-V semiconductor layer 20.

[0027] The semiconductor light receiving element 10 may further include a second conductivity type III-V group semiconductor layer 22. In the first direction D1, the second III-V group semiconductor layer 14 is provided between the III-V group semiconductor layer 22 and the light receiving layer 16. The III-V group semiconductor layer 22 may be a contact layer. The III-V group semiconductor layer 22 is Ga z In 1-z It may be an As layer (also called a GaInAs layer). z is the gallium (Ga) composition. z is greater than 0 and less than 1. An electrode 40 may be connected to the III-V semiconductor layer 22.

[0028] The semiconductor light receiving element 10 can detect incident light L. The incident light L may be visible light or infrared light having a wavelength of 0.4 to 3 μm. The incident light L may travel in a first direction D1. The incident light L may pass through the substrate 18 and enter the light receiving layer 16. The semiconductor light receiving element 10 may be used in a spectroscopy system, an imaging system, or an optical communication system of a gas analyzer.

[0029] 2 is a cross-sectional view schematically illustrating a light-receiving layer included in the semiconductor light-receiving element of FIG. 1. As illustrated in FIG. 2, the light-receiving layer 16 includes a plurality of unit structures U1 stacked in a first direction D1. Adjacent unit structures U1 may be in contact with each other. The number of unit structures U1 may be 100 to 500. The plurality of unit structures U1 form a superlattice.

[0030] 3 is a cross-sectional view schematically illustrating a unit structure included in the absorption layer of FIG. 2. As shown in FIG. 3, each unit structure U1 is made of gallium arsenide antimonide (GaAs y Sb 1-y The layer L1 includes an indium arsenide (InAs) layer L2 and a gallium arsenide (GaAs) layer L3. y is the arsenic (As) composition. y is greater than 0 and less than 1. y may be 0.45 to 0.6. In this case, GaAs y Sb 1-y Layer L1 can be lattice matched to the InP layer. y Sb 1-y The layer L1, the InAs layer L2, and the GaAs layer L3 may be stacked in a first direction D1. y Sb 1-y The layer L1, the InAs layer L2, and the GaAs layer L3 may be stacked in this order in the first direction D1. y Sb 1-y It may be provided between the layer L1 and the GaAs layer L3. y Sb 1-y The layer L1, the GaAs layer L3, and the InAs layer L2 may be stacked in this order in the first direction D1. y Sb 1-yThe InAs layer L2 may be in contact with the adjacent GaAs layer L3. y Sb 1-y The layer L1 may be in contact with an adjacent layer (InAs layer L2 or GaAs layer L3). In one unit structure U1, a layer (InAs layer L2 or GaAs layer L3) located at an end in the first direction D1 may be in contact with the GaAs layer in the adjacent unit structure U1. y Sb 1-y Layer L1 may be in contact with GaAs. y Sb 1-y Layer L1 can function as an electron barrier layer or a hole well layer, and InAs layer L2 and GaAs layer L3 can function as electron well layers or hole barrier layers.

[0031] In each unit structure U1, the number of pairs including a single InAs layer L2 and a single GaAs layer L3 is k. k may be 1 to 10. k may be 2 or more. In this case, the InAs layer L2 and the GaAs layer L3 may be alternately arranged. The InAs layer L2 and the GaAs layer L3 may contact each other. As shown in FIG. 3, the GaAs y Sb 1-y In each of the k pairs on the layer L1, an InAs layer L2 and a GaAs layer L3 may be stacked in this order in the first direction D1. y Sb 1-y In each of the k pairs on the layer L1, a GaAs layer L3 and an InAs layer L2 may be stacked in this order in the first direction D1.

[0032] The InAs layer L2 and the GaAs layer L3 are GaAs y Sb 1-y The thickness of the InAs layer L2 may be the same as or different from the thickness of the GaAs layer L3. y Sb 1-y The thickness of layer L1 may be 2.5 to 6.3 nm, the thickness of InAs layer L2 may be 0.2 to 1.6 nm, and the thickness of GaAs layer L3 may be 0.2 to 1.5 nm.

[0033] In the semiconductor light-receiving element 10, the InAs layer L2 and GaAs layer L3 in each unit structure U1 function as electron well layers. The absorption edge wavelength (cutoff wavelength) of the semiconductor light-receiving element 10 can be made longer than when the electron well layer in each unit structure consists of only a GaInAs layer. This is thought to be because the intrinsic energy of the wave function of the conduction band in the electron well layer is different. Furthermore, the semiconductor light-receiving element 10 can reduce the average strain of each layer in each unit structure U1. The average strain of each layer is, for example, about 0.1%.

[0034] Various experiments conducted to evaluate the unit structure U1 of Fig. 3 will be described below. The experiments described below do not limit the present disclosure.

[0035] (First experiment) The light-receiving layer of the semiconductor light-receiving element in the first experiment had the following structure: Each unit structure in the light-receiving layer was a GaAs layer with a thickness of 5 nm. y Sb 1-y The layer includes an InAs layer having a thickness of 0.62 nm and a GaAs layer having a thickness of 0.56 nm (see FIG. 3). y is 0.52. The number of pairs including an InAs layer and a GaAs layer is four. y Sb 1-y The InAs and GaAs layers function as electron barrier layers, and the InAs and GaAs layers function as electron well layers.

[0036] (Second experiment) The light-receiving layer of the semiconductor light-receiving element in the second experiment had the following structure: Each unit structure of the light-receiving layer was a GaAs layer with a thickness of 5 nm. y Sb 1-y a Ga layer with a thickness of 5 nm x In 1-x The GaAs layer is included. y is 0.51. x is 0.47. y Sb 1-y The Ga layer acts as an electron barrier layer. x In 1-x The As layer functions as an electron well layer.

[0037] (First experiment results) For the absorption layers of the semiconductor light-receiving elements according to Experiments 1 and 2, the band offset energy and the square of the absolute value of the magnitude of the wave function were calculated by simulation. The results are shown in FIGS. 4 and 5.

[0038] 4 and 5 are graphs showing examples of energy band diagrams in the absorption layer of the semiconductor light-receiving element according to the first and second experiments, respectively. In the graphs of FIGS. 4 and 5, the horizontal axis indicates the position of each atom in the first direction D1. The vertical axis on the left side of the graph indicates the band offset energy (eV). ECBO indicates the band offset energy of the conduction band (also called the conduction band edge) at the Γ point where the wave number is 0. EVBO indicates the band offset energy of the valence band (also called the valence band edge) at the Γ point where the wave number is 0. The vertical axis on the right side of the graph indicates the square of the absolute value of the magnitude of the wave function (arbitrary units). |ψCBM| 2 denotes the square of the absolute value of the wave function magnitude at the conduction band edge. |ψCBM| 2 is located above 0 on the right vertical axis. |ψVBM| 2 denotes the square of the absolute value of the wave function magnitude at the valence band edge. |ψVBM| 2 is located below 0 on the right vertical axis.

[0039] As shown in FIGS. 4 and 5, the energy bands and wave functions in the electron well layer are different between the first and second experiments.

[0040] (Third experiment) The light-receiving layer of the semiconductor light-receiving element according to the third experiment had the following structure: Each unit structure of the light-receiving layer was a GaAs layer with a thickness of 5 nm. y Sb 1-y The layer includes an InAs layer, an InAs layer having a thickness of 1.2 nm, and a GaAs layer having a thickness of 1.1 nm (see Figure 3). y is 0.53. The number of pairs including an InAs layer and a GaAs layer is two. y Sb 1-y The InAs and GaAs layers function as electron barrier layers, and the InAs and GaAs layers function as electron well layers.

[0041] GaAs with a thickness of 5 nm y Sb 1-y The layer is 17 GaAs y Sb 1-y The monolayer refers to a layer containing a single molecule (III-V compound semiconductor molecule) in the thickness direction. y Sb 1-y The monolayer is a single GaAs y Sb 1-y The InAs layer has a thickness of 1.2 nm and contains four InAs monolayers. Each InAs monolayer contains a single InAs molecule across its thickness. The GaAs layer has a thickness of 1.1 nm and contains four GaAs monolayers. Each GaAs monolayer contains a single GaAs molecule across its thickness.

[0042] (Experiment 4) The absorption layer of the semiconductor light-receiving element according to the fourth experiment had the following structure: Each unit structure of the absorption layer was a GaAs layer with a thickness of 5 nm. y Sb 1-y a Ga layer with a thickness of 5 nm x In 1-x The y is 0.51 and the x is 0.47. The Ga layer has a thickness of 5 nm. x In 1-x The As layer has 17 Ga atoms. x In 1-x Contains a monolayer of As. y Sb 1-y The Ga layer acts as an electron barrier layer. x In 1-x The As layer functions as an electron well layer.

[0043] (Second experiment results) For the absorption layers of the semiconductor light receiving elements according to the third and fourth experiments, the spectrum of the optical absorption coefficient at an operating temperature of 200 K was calculated by simulation. The results are shown in FIG.

[0044] FIG. 6 is a graph showing an example of the spectrum of the optical absorption coefficient obtained in the third and fourth experiments. In the graph of FIG. 6, the vertical axis represents the optical absorption coefficient (cm -1 ) The horizontal axis represents wavelength (μm). The solid line E1 represents the spectrum obtained for the absorption layer of the semiconductor light receiving element in the third experiment. The dashed line E2 represents the spectrum obtained for the absorption layer of the semiconductor light receiving element in the fourth experiment.

[0045] As shown in Figure 6, the absorption edge wavelength indicated by the solid line E1 was approximately 2.8 μm. The absorption edge wavelength indicated by the dashed line E2 was approximately 2.5 μm. In the third experiment, a longer absorption edge wavelength was obtained than in the fourth experiment. This shows that when the electron well layer contains an InAs layer and a GaAs layer, a longer absorption edge wavelength can be obtained than when the electron well layer consists of only a GaInAs layer. Furthermore, in the third experiment, it can be seen that the reduction in the optical absorption coefficient is suppressed in the wavelength range below 2.5 μm.

[0046] Modified examples of the unit structures included in the light-receiving layer 16 will be described below.

[0047] 7 is a cross-sectional view schematically illustrating a modified example of the unit structure included in the absorption layer of FIG. 2. The unit structure U2 shown in FIG. 7 may be included in the absorption layer 16 of FIG. 2 in place of the unit structure U1 of FIG. 3. As shown in FIG. 7, the unit structure U2 is Ga x In 1-x The unit structure U1 has the same configuration as the unit structure U1 except that it further includes an As layer L4. x is the Ga composition. x is greater than 0 and less than 1. x may be 0.4 to 0.55. The InAs layer L2 and the GaAs layer L3 are arranged in the first direction D1. y Sb 1-y Layers L1 and Ga x In 1-x It is arranged between the As layer L4 and the Ga x In 1-x The As layer L4 may contact the adjacent layer (InAs layer L2 or GaAs layer L3). x In 1-x The As layer L4 is a GaAs layer in the adjacent unit structure U2. y Sb1-y It may contact the layer L1. x In 1-x The As layer L4 can function as an electron well layer or a hole barrier layer together with the InAs layer L2 and the GaAs layer L3.

[0048] Ga x In 1-x The As layer L4 may have a thickness greater than the thickness of the InAs layer L2 and the thickness of the GaAs layer L3. x In 1-x The As layer L4 is GaAs y Sb 1-y It may have a thickness smaller than that of layer L1. x In 1-x The thickness of the As layer L4 may be 0.8 to 2.1 nm.

[0049] The semiconductor light-receiving element having the unit structure U2 can have a longer absorption edge wavelength, similar to the semiconductor light-receiving element 10 having the unit structure U1. x In 1-x By adjusting the Ga composition x in the As layer L4, the lattice strain caused by the InAs layer L2 and the GaAs layer L3 can be canceled, thereby reducing the average strain in the electron well layer.

[0050] Various experiments conducted to evaluate the unit structure U2 of Fig. 7 will be described below. The experiments described below do not limit the present disclosure.

[0051] (5th experiment) The light-receiving layer of the semiconductor light-receiving element according to the fifth experiment had the following structure: Each unit structure of the light-receiving layer was a GaAs y Sb 1-y a 0.6 nm thick InAs layer; a 0.6 nm thick GaAs layer; and a 1.5 nm thick GaAs layer. x In 1-x The number of pairs including an InAs layer and a GaAs layer is three (see Figure 7). y is 0.51. x is 0.50. y Sb 1-yThe InAs layer, GaAs layer, and GaAs layer act as electron barrier layers. x In 1-x The As layer acts as an electron well layer. The 0.6 nm thick InAs layer contains two InAs monolayers. The 0.6 nm thick GaAs layer contains two GaAs monolayers. The 1.5 nm thick GaAs layer contains two GaAs monolayers. x In 1-x The As layer is composed of five 1.5 nm thick Ga layers. x In 1-x Contains an AsAs monolayer.

[0052] (Third experiment results) For the absorption layers of the semiconductor light receiving elements according to the fourth and fifth experiments, the spectrum of the optical absorption coefficient at an operating temperature of 200 K was calculated by simulation. The results are shown in FIG.

[0053] Fig. 8 is a graph showing examples of the spectra of the optical absorption coefficient obtained in Experiments 4 and 5. The axes of the graph in Fig. 8 are the same as those of the graph in Fig. 6. The solid line E3 shows the spectrum obtained for the absorption layer of the semiconductor light receiving element in Experiment 5.

[0054] As shown in Figure 8, the absorption edge wavelength of the solid line E3 was approximately 2.7 μm. The absorption edge wavelength of the dashed line E2 was approximately 2.5 μm. In the fifth experiment, a longer absorption edge wavelength was obtained than in the fourth experiment. This shows that when the electron well layer includes an InAs layer, a GaAs layer, and a GaInAs layer, a longer absorption edge wavelength can be obtained than when the electron well layer consists of only a GaInAs layer.

[0055] Although the preferred embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the above embodiments.

[0056] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above meaning, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0057] 10...Semiconductor light receiving element 12...First III-V semiconductor layer 14...Second III-V group semiconductor layer 16...Light-receiving layer 18... Circuit board 20...III-V group semiconductor layer 22...III-V semiconductor layer 30...Electrode 40...electrode D1…first direction E1…solid line E2...dashed line E3…solid line L…Incoming light L1...GaAs y Sb 1-y layer L2…InAs layer L3: GaAs layer L4…Ga x In 1-x As layer U1...Unit structure U2...Unit structure

Claims

1. a first group III-V semiconductor layer of a first conductivity type; a second group III-V semiconductor layer of a second conductivity type; a light-receiving layer provided between the first group III-V semiconductor layer and the second group III-V semiconductor layer in a first direction; Equipped with the light receiving layer includes a plurality of unit structures stacked in the first direction, each of the plurality of unit structures includes a gallium arsenide layer, an indium arsenide layer, and a gallium arsenide antimony layer; a pair including the gallium arsenide layer and the indium arsenide layer functions as a hole barrier layer and an electron well layer for the gallium arsenide antimonide layer; The semiconductor light-receiving element, wherein the gallium arsenide layer and the indium arsenide layer have a thickness smaller than a thickness of the gallium arsenide antimonide layer.

2. Each of the plurality of unit structures further comprises a gallium indium arsenide layer; 2. The semiconductor light-receiving element according to claim 1, wherein the gallium arsenide layer and the indium arsenide layer are disposed between the gallium indium arsenide layer and the gallium arsenide antimony layer in the first direction.

3. 3. The semiconductor light-receiving element according to claim 2, wherein the gallium indium arsenide layer has a gallium composition of 0.4 to 0.

55.

4. 4. The semiconductor light-receiving element according to claim 2, wherein the thickness of said gallium indium arsenide layer is 0.8 to 2.1 nm.

5. 3. The semiconductor light-receiving element according to claim 1, wherein the thickness of said gallium arsenide layer is 0.2 to 1.5 nm.

6. 3. The semiconductor light-receiving element according to claim 1, wherein the thickness of said indium arsenide layer is 0.2 to 1.6 nm.

7. 3. The semiconductor light-receiving element according to claim 1, wherein the thickness of said gallium arsenide antimonide layer is 2.5 to 6.3 nm.

8. 3. The semiconductor light-receiving element according to claim 1, wherein the number of pairs including the gallium arsenide layer and the indium arsenide layer in each of the plurality of unit structures is 1 to 10.

9. 3. The semiconductor light-receiving element according to claim 1, wherein the arsenic composition of said gallium arsenide antimonide layer is 0.45 to 0.

6.

10. Further comprising an indium phosphide substrate, 3. The semiconductor light-receiving element according to claim 1, wherein the first III-V semiconductor layer is provided between the indium phosphide substrate and the light-receiving layer in the first direction.

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