# US 2021/0242361 A1 · Photodetection element > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0242361 A1 - Document ID: US20210242361A1 - Status: Published application - Kind: A1 - Application number: 17/053,604 - Filed: 2018-05-11 - Published: 2021-08-05 - Earliest claimed: 2018-05-11 - Assignees: NEC Corporation - Applicants: NEC Corporation - Inventors: Yuichi IGARASHI - Web page: https://patentgrep.com/patent/US20210242361A1 ## CPC - H10F 30/2215: {the devices comprising active layers made of only Group III-V materials} - H10F 30/21: the devices being sensitive to infrared, visible or ultraviolet radiation - H10F 30/223: the potential barrier being a PIN barrier - H10F 77/1248: {having three or more elements, e.g. GaAlAs, InGaAs or InGaAsP} - H10F 77/14: Shape of semiconductor bodies; Shapes, relative sizes or dispositions of semiconductor regions within semiconductor bodies - H10F 77/146: {Superlattices; Multiple quantum well structures} - H10F 77/147: {Shapes of bodies} - H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION ## Abstract A photodetection element that includes: a substrate with a high infrared transmittance in a desired wavelength region; an electron barrier layer of a type-I superlattice structure, the electron barrier layer being formed above the substrate and lattice-matched to the substrate; and a light-receiving layer of a type-II superlattice structure, formed in contact with the electron barrier layer. ## Claims ### Claim 1 A photodetection element comprising: a substrate with a high infrared transmittance in a desired wavelength region; an electron barrier layer of a type-I superlattice structure, the electron barrier layer being formed above the substrate and lattice-matched to the substrate; and a light-receiving layer of a type-II superlattice structure, formed in contact with the electron barrier layer. ### Claim 2 (depends on 1) The photodetection element according to claim 1, wherein ground-state energy of a hole miniband of the electron barrier layer is substantially equal to ground-state energy of a hole miniband of the light-receiving layer. ### Claim 3 (depends on 1) The photodetection element according to claim 1, wherein the substrate is an InP substrate. ### Claim 4 (depends on 1) The photodetection element according to claim 1, wherein the electron barrier layer includes a first barrier layer and a second barrier layer, and a thickness of the second barrier layer is adjusted in such a way that the ground-state energy of the hole miniband of the electron barrier layer matches the ground-state energy of the hole miniband of the light-receiving layer. ### Claim 5 (depends on 4) The photodetection element according to claim 4, wherein the first barrier layer is made of AlAsSb, and the second barrier layer is made of GaAsSb in the electron barrier layer. ### Claim 6 (depends on 5) The photodetection element according to claim 5, wherein the light-receiving layer includes a first light-receiving layer and a second light-receiving layer, and the first light-receiving layer is made of InGaAs, and the second light-receiving layer is made of GaAsSb. ### Claim 7 (depends on 6) The photodetection element according to claim 6, wherein ratios of As and Sb in the first barrier layer and the second barrier layer are equal. ### Claim 8 (depends on 6) The photodetection element according to claim 6, wherein ratios of As and Sb in the second barrier layer included in the electron barrier layer and the second light-receiving layer included in the light-receiving layer are equal. ### Claim 9 (depends on 8) The photodetection element according to claim 8, wherein a common layer is used as the second barrier layer of the electron barrier layer and as the second light-receiving layer of the light-receiving layer at a boundary between the electron barrier layer and the light-receiving layer. ### Claim 10 (depends on 6) The photodetection element according to claim 6, wherein rates of As among group V elements contained in the first barrier layer and the second barrier layer are each 0.55. ### Claim 11 (depends on 6) The photodetection element according to claim 6, wherein a rate of In among group III elements contained in the first light-receiving layer is 0.52, and a rate of As among group V elements contained in the second light-receiving layer is 0.55. ### Claim 12 (depends on 6) The photodetection element according to claim 6, wherein at least one of the electron barrier layer and the light-receiving layer contains P. ### Claim 13 (depends on 1) The photodetection element according to claim 1, further comprising: two contact layers sandwiching the electron barrier layer and the light-receiving layer. ### Claim 14 (depends on 13) The photodetection element according to claim 13, wherein both of the two contact layers contain an n-type dopant. ### Claim 15 (depends on 13) The photodetection element according to claim 13, wherein one of the two contact layers contains a p-type dopant, another of the two contact layers contains an n-type dopant, and the electron barrier layer is disposed between the contact layer containing the p-type dopant and the light-receiving layer. ### Claim 16 (depends on 13) The photodetection element according to claim 13, further comprising: a buffer layer disposed between at least one of the two contact layers and the substrate, the buffer layer being made of a same material as the substrate and lattice-matched to the substrate. ### Claim 17 (depends on 15) The photodetection element according to claim 15, wherein a hole barrier layer is disposed between the light-receiving layer and the contact layer. ### Claim 18 (depends on 1) The photodetection element according to claim 1, wherein a degree of mismatch between lattice constants of the electron barrier layer and the substrate is less than 1%. ### Claim 19 (depends on 1) The photodetection element according to claim 1, further comprising: an infrared detecting structure in which detection units each including at least the electron barrier layer and the light-receiving layer are arranged in an array on the substrate. ### Claim 20 (depends on 19) An infrared detecting apparatus comprising: the photodetection element according to claim 19; a readout circuit that reads electrical signal of infrared rays detected by the photodetection element for each of the detection units, the readout circuit being flip-chip bonded to the photodetection element; an infrared optical system that focuses infrared light on the infrared detecting structure of the photodetection element; and an output circuit that outputs a signal based on infrared light detected for each of the detection units.