# US 12,009,450 B2 · Optical receiving element and manufacturing method therefor

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- Number: US 12,009,450 B2
- Document ID: US12009450B2
- Status: Granted
- Kind: B2
- Application number: 17/776,367
- Filed: 2019-11-18
- Published: 2022-12-15
- Granted: 2024-06-11
- Earliest claimed: 2019-11-18
- Assignees: Nippon Telegraph and Telephone Corporation
- Applicants: Nippon Telegraph and Telephone Corporation
- Inventors: Yuki Yamada; Masahiro Nada
- Web page: https://patentgrep.com/patent/US12009450B2

## CPC

- H10F 30/2255: {in which the active layers form heterostructures, e.g. SAM structures}
- H10F 71/1272: {comprising at least three elements, e.g. GaAlAs or InGaAsP}
- H10F 71/139: {using temporary substrates}
- H10F 77/1248: {having three or more elements, e.g. GaAlAs, InGaAs or InGaAsP}
- H10F 77/147: {Shapes of bodies}
- H10F 77/241: {comprising ring electrodes}
- H10F 77/413: {directly associated or integrated with the devices, e.g. back reflectors (directly associated or integrated with photovoltaic cells H10F77/42)}
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION

## Abstract

A first n-type contact layer, a second n-type contact layer, a multiplication layer, an electric field control layer, a light absorbing layer, and a p-type contact layer are layered in this order on a substrate. The second n-type contact layer is formed between the first n-type contact layer and the light absorbing layer, is made to have an area smaller than that of the light absorbing layer in a plan view, and is disposed inside the light absorbing layer in a plan view.

## Claims

### Claim 1

A light receiving element, comprising:
a first n-type contact layer on a substrate, the first n-type contact layer being composed of a first n-type semiconductor;
a light absorbing layer on the first n-type contact layer, the light absorbing layer being composed of a first semiconductor;
a p-type contact layer on the light absorbing layer, the p-type contact layer being composed of a p-type semiconductor;
a second n-type contact layer between the first n-type contact layer and the light absorbing layer, the second n-type contact layer being composed of a second n-type semiconductor, the second n-type contact layer having an area smaller than an area of the light absorbing layer in a plan view, the second n-type contact layer overlapping the light absorbing layer in the plan view;
a first electrode on the p-type contact layer;
a second electrode on the first n-type contact layer around a region of the second n-type contact layer; and
a reflection layer formed on the p-type contact layer, the reflection layer having an area smaller than an area of the p-type contact layer in the plan view and being disposed inside the p-type contact layer in the plan view, wherein the first electrode is disposed on the p-type contact layer around the reflection layer.

### Claim 2 (depends on 1)

The light receiving element according to claim 1, further comprising:
a multiplication layer between the second n-type contact layer and the light absorbing layer, the multiplication layer being composed of a second semiconductor; and
an electric field control layer between the multiplication layer and the light absorbing layer, the electric field control layer being composed of a third semiconductor.

### Claim 3 (depends on 1)

The light receiving element according to claim 1, wherein the substrate is composed of a fourth semiconductor having a thermal conductivity higher than a thermal conductivity of InP.

### Claim 4

A method for producing a light receiving element, the method comprising:
forming a first n-type contact layer composed of a first n-type semiconductor on a substrate;
forming, on another substrate, a p-type contact layer composed of a p-type semiconductor, a light absorbing layer composed of a first semiconductor, and a semiconductor layer composed of a second n-type semiconductor in this order;
patterning the semiconductor layer to a predetermined area in a plan view to form a second n-type contact layer;
bonding the substrate and the other substrate such that a side on which the first n-type contact layer is formed and a side on which the second n-type contact layer faces each other;
removing the other substrate after the substrate and the other substrate are bonded to each other to layer the first n-type contact layer, the second n-type contact layer, the light absorbing layer, and the p-type contact layer in this order on the substrate;
patterning the light absorbing layer and the p-type contact layer to make an area of each of the light absorbing layer and the p-type contact layer larger than the area of the second n-type contact layer in the plan view such that the second n-type contact layer is disposed inside the light absorbing layer in the plan view;
forming a first electrode on the p-type contact layer;
forming a second electrode on the first n-type contact layer around a region where the second n-type contact layer is formed; and
forming a reflection layer on the p-type contact layer, the reflection layer having an area smaller than an area of the p-type contact layer in the plan view and being disposed inside the p-type contact layer in the plan view, wherein the first electrode is disposed on the p-type contact layer around the reflection layer.

### Claim 5 (depends on 4)

The method for producing a light receiving element according to claim 4, wherein:
in the forming of, on the other substrate, the p-type contact layer, the light absorbing layer, and the semiconductor layer in this order, the p-type contact layer, the light absorbing layer, an electric field control layer composed of a semiconductor, a multiplication layer composed of a semiconductor, and the semiconductor layer are formed in this order,
in the removing of the other substrate after the substrate and the other substrate are bonded to each other to layer the first n-type contact layer, the second n-type contact layer, the light absorbing layer, and the p-type contact layer in this order on the substrate, the first n-type contact layer, the second n-type contact layer, the multiplication layer, the electric field control layer, the light absorbing layer, and the p-type contact layer are layered in this order on the substrate, and
in the patterning of the light absorbing layer and the p-type contact layer to make the area of each of the light absorbing layer and the p-type contact layer larger than the area of the second n-type contact layer in the plan view such that the second n-type contact layer is disposed inside the light absorbing layer in the plan view, the multiplication layer, the electric field control layer, the light absorbing layer, and the p-type contact layer are patterned to make an area of each of the multiplication layer, the electric field control layer, the light absorbing layer, and the p-type contact layer larger than the area of the second n-type contact layer in the plan view, and the second n-type contact layer is disposed inside the light absorbing layer in the plan view.

### Claim 6 (depends on 4)

The method for producing a light receiving element according to claim 4, wherein the substrate is composed of a semiconductor having a thermal conductivity higher than a thermal conductivity of InP.

### Claim 7

A method for forming a light receiving element, the method comprising:
forming a first n-type contact layer comprising a first n-type semiconductor on a first substrate;
forming, on a second substrate, a p-type contact layer comprising of a p-type semiconductor, a light absorbing layer comprising of a first semiconductor, and a semiconductor layer comprising of a second n-type semiconductor in this order;
patterning the semiconductor layer to have a first area in a plan view to form a second n-type contact layer;
bonding the first substrate and the second substrate such that a side on which the first n-type contact layer is formed and a side on which the second n-type contact layer faces each other;
removing the second substrate after bonding the first substrate to the second substrate;
patterning the light absorbing layer and the p-type contact layer to make a second area of the light absorbing layer and a third area of the p-type contact layer larger than the first area of the second n-type contact layer in the plan view such that the second n-type contact layer overlaps the light absorbing layer in the plan view; and
forming a reflection layer on the p-type contact layer, the reflection layer having a fourth area smaller than the third area of the p-type contact layer in the plan view and overlapping the p-type contact layer in the plan view.

### Claim 8 (depends on 7)

The method for producing a light receiving element according to claim 7, further comprising:
forming a first electrode on the p-type contact layer; and
forming a second electrode on the first n-type contact layer around a region where the second n-type contact layer is formed.