Search

US-12622072-B2 - Semiconductor photodetector

US12622072B2US 12622072 B2US12622072 B2US 12622072B2US-12622072-B2

Abstract

A semiconductor photodetector includes 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 an optical absorption layer disposed between the first group III-V semiconductor layer and the second group III-V semiconductor layer in a first direction. The optical absorption 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 antimonide layer. The gallium arsenide layer and the indium arsenide layer each have a thickness smaller than a thickness of the gallium arsenide antimonide layer.

Inventors

  • Takashi Kato

Assignees

  • SUMITOMO ELECTRIC INDUSTRIES, LTD.

Dates

Publication Date
20260505
Application Date
20230906
Priority Date
20220930

Claims (14)

  1. 1 . A semiconductor photodetector comprising: 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 an optical absorption layer disposed between the first group III-V semiconductor layer and the second group III-V semiconductor layer in a first direction, wherein the optical absorption layer includes a plurality of unit structures stacked in the first direction, wherein each of the plurality of unit structures includes a gallium arsenide layer, an indium arsenide layer, and a gallium arsenide antimonide layer, wherein the gallium arsenide layer and the indium arsenide layer each have a thickness smaller than a thickness of the gallium arsenide antimonide layer, wherein the gallium arsenide antimonide layer functions as an electron-barrier layer or a hole-well layer, and the gallium arsenide layer and the indium arsenide layer function as an electronic well layer or a hole barrier layer, and wherein the gallium arsenide antimonide layer is in contact with the gallium arsenide layer or the indium arsenide layer within each of the plurality of unit structures.
  2. 2 . The semiconductor photodetector according to claim 1 , wherein each of the plurality of unit structures further includes a gallium indium arsenide layer, and the gallium arsenide layer and the indium arsenide layer are disposed between the gallium indium arsenide layer and the gallium arsenide antimonide layer in the first direction.
  3. 3 . The semiconductor photodetector according to claim 2 , wherein the gallium indium arsenide layer has a gallium fraction of 0.4 to 0.55.
  4. 4 . The semiconductor photodetector according to claim 2 , wherein the gallium indium arsenide layer has a thickness of 0.8 nm to 2.1 nm.
  5. 5 . The semiconductor photodetector according to claim 1 , wherein the gallium arsenide layer has a thickness of 0.2 nm to 1.5 nm.
  6. 6 . The semiconductor photodetector according to claim 1 , wherein the indium arsenide layer has a thickness of 0.2 nm to 1.6 nm.
  7. 7 . The semiconductor photodetector according to claim 1 , wherein the gallium arsenide antimonide layer has a thickness of 2.5 nm to 6.3 nm.
  8. 8 . The semiconductor photodetector according to claim 1 , wherein, in each of the plurality of unit structures, the number of pairs including the gallium arsenide layer and the indium arsenide layer is 1 to 10.
  9. 9 . The semiconductor photodetector according to claim 1 , wherein the gallium arsenide antimonide layer has an arsenic fraction of 0.45 to 0.6.
  10. 10 . The semiconductor photodetector according to claim 1 , further comprising: an indium phosphide substrate, wherein the first group III-V semiconductor layer is disposed between the indium phosphide substrate and the optical absorption layer in the first direction.
  11. 11 . The semiconductor photodetector according to claim 1 , wherein the number of the plurality of unit structures is 100 to 500.
  12. 12 . The semiconductor photodetector according to claim 1 , wherein the plurality of unit structures constitute a superlattice.
  13. 13 . The semiconductor photodetector according to claim 1 , wherein, in each of the plurality of unit structures, the indium arsenide layer is disposed between the gallium arsenide antimonide layer and the gallium arsenide layer in the first direction.
  14. 14 . The semiconductor photodetector according to claim 1 , wherein the optical absorption layer has an optical absorption edge wavelength of 2.5 μm or more.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application claims priority based on Japanese Patent Application No. 2022-157888 filed on Sep. 30, 2022, and the entire contents of the Japanese patent application are incorporated herein by reference. TECHNICAL FIELD The present disclosure relates to a semiconductor photodetector. BACKGROUND Non-PTL 1 discloses a photodiode comprising an optical absorption layer provided on an n-type indium phosphide (InP) substrate. The optical absorption layer has 150 pairs of type-II superlattices. One pair includes a gallium indium arsenide (GaInAs) layer and a gallium arsenide antimonide (GaAsSb) layer. With this photodiode, a cut-off wavelength (a wavelength of the optical absorption edge) of 2.39 μm is obtained. Non-PTL 2 discloses a photodiode comprising an optical absorption layer provided on an n-type InP substrate. The optical absorption layer has 100 pairs of type-II superlattices. One pair includes a GaInAs layer and a GaAsSb layer. The optical absorption layer has a strain-compensated quantum well structure. Non-PTL 1: Rubin Sidhu, et al, “A Long-Wavelength Photodiode on InP Using Lattice-Matched GaInAs—GaAsSb Type-II Quantum Wells” IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 17, NO. 12, DECEMBER 2005, p. 2715 to 2717 Non-PTL 2: Baile Chen, et al, “SWIR/MWIR InP-Based p-i-n Photodiodes with InGaAs/GaAsSb Type-II Quantum Wells” IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 47, NO. 9, SEPTEMBER 2011, p. 1244 to 1250 SUMMARY A semiconductor photodetector according to one aspect of the present disclosure includes 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 an optical absorption layer disposed between the first group III-V semiconductor layer and the second group III-V semiconductor layer in a first direction. The optical absorption 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 antimonide layer. The gallium arsenide layer and the indium arsenide layer each have a thickness smaller than a thickness of the gallium arsenide antimonide layer. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view illustrating a semiconductor photodetector according to an embodiment. FIG. 2 is a schematic cross-sectional view illustrating an optical absorption layer included in the semiconductor photodetector of FIG. 1. FIG. 3 is a schematic cross-sectional view illustrating a unit structure included in the optical absorption layer of FIG. 2. FIG. 4 is a graph illustrating an example of an energy band diagram in an optical absorption layer of a semiconductor photodetector according to a first experiment. FIG. 5 is a graph illustrating an example of an energy band diagram in an optical absorption layer of a semiconductor photodetector according to a second experiment. FIG. 6 is a graph illustrating examples of spectra of optical absorption coefficients obtained in a third experiment and a fourth experiment. FIG. 7 is a schematic cross-sectional view illustrating a modification of a unit structure included in the optical absorption layer of FIG. 2. FIG. 8 is a graph illustrating examples of spectra of optical absorption coefficients obtained in the fourth experiment and a fifth experiment. DETAILED DESCRIPTION The present disclosure provides a semiconductor photodetector having a long wavelength of the optical absorption edge. Description of Embodiments of Present Disclosure First, embodiments of the present disclosure will be listed and explained. (1) A semiconductor photodetector according to one aspect of the present disclosure includes 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 an optical absorption layer disposed between the first group III-V semiconductor layer and the second group III-V semiconductor layer in a first direction. The optical absorption 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 antimonide layer. The gallium arsenide layer and the indium arsenide layer each have a thickness smaller than a thickness of the gallium arsenide antimonide layer. According to the semiconductor light-receiving element, a wavelength of the optical absorption edge can be made longer than in the case where the electronic well layer in each unit structure is composed only of a GaInAs layer. This is considered to be because the eigenenergy of the wave function of the conduction band in the electronic well layer is different. (2) In (1), each of the plurality of unit structures may further include a gallium indium arsenide layer. The gallium arsenide layer and the indium arseni