# US 2014/0197373 A1 · Light-receiving device and method for producing the same

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- Number: US 2014/0197373 A1
- Document ID: US20140197373A1
- Status: Published application
- Kind: A1
- Application number: 14/154,861
- Filed: 2014-01-14
- Published: 2014-07-17
- Earliest claimed: 2013-01-15
- Assignees: Sumitomo Electric Industries, Ltd.
- Applicants: Sumitomo Electric Industries, Ltd.
- Inventors: Yasuhiro IGUCHI; Youichi NAGAI
- Web page: https://patentgrep.com/patent/US20140197373A1

## CPC

- H10F 30/222: the potential barrier being a PN heterojunction
- H10F 30/2215: {the devices comprising active layers made of only Group III-V materials}
- H10F 30/223: the potential barrier being a PIN barrier
- H10F 39/107: {having multiple elements covered by H10F30/00 in a repetitive configuration, e.g. radiation detectors comprising photodiode arrays}
- H10F 71/1272: {comprising at least three elements, e.g. GaAlAs or InGaAsP}
- H10F 77/1248: {having three or more elements, e.g. GaAlAs, InGaAs or InGaAsP}
- H10F 77/146: {Superlattices; Multiple quantum well structures}
- H10F 77/1468: {Doped superlattices, e.g. N-I-P-I superlattices}
- H10H 20/824: comprising only Group III-V materials, e.g. GaP
- Y02E 10/544: Solar cells from Group III-V materials
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- H10H: INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A light-receiving device includes a light-receiving layer having an undoped multi-quantum well structure; a cap layer disposed on the light-receiving layer, the cap layer including a semiconductor layer doped with a p-type impurity; a mesa structure including the cap layer; a p-type region extending from the p-type semiconductor layer toward the light-receiving layer, the p-type region including the p-type impurity diffused from the semiconductor layer in the mesa structure; a p-n junction formed at an end of the p-type region; and an electrode disposed on the cap layer of the mesa structure. The mesa structure is defined by a trench surrounding the mesa. The trench has a bottom that reaches the vicinity of an upper surface of the light-receiving layer. The p-n junction is located in the light-receiving layer or at the boundary between the light-receiving layer and the cap layer disposed on the light-receiving layer.

## Claims

### Claim 1

A light-receiving device comprising:
a light-receiving layer disposed on a substrate, the light-receiving layer having an undoped multi-quantum well structure;
a cap layer disposed on the light-receiving layer, the cap layer including a p-type semiconductor layer doped with a p-type impurity;
a mesa structure disposed on the substrate, the mesa structure including the cap layer;
a p-type region extending from the p-type semiconductor layer toward the light-receiving layer, the p-type region including the p-type impurity diffused from the p-type semiconductor layer in the cap layer in the mesa structure;
a p-n junction formed at an end of the p-type region; and
an electrode disposed on the cap layer of the mesa structure,
wherein the mesa structure is defined by a trench surrounding the mesa,
the trench has a bottom that reaches the vicinity of an upper surface of the light-receiving layer, and
the p-n junction is located in the light-receiving layer or at the boundary between the light-receiving layer and the cap layer disposed on the light-receiving layer.

### Claim 2 (depends on 1)

The light-receiving device according to claim 1, wherein the cap layer includes a p-type contact layer doped with the p-type impurity and a concentration adjusting layer, the concentration adjusting layer being not doped or being doped with a lower concentration of an impurity than the p-type contact layer,
the concentration adjusting layer is disposed between the p-type contact layer and the light-receiving layer, and
the electrode is disposed on the p-type contact layer.

### Claim 3 (depends on 2)

The light-receiving device according to claim 2, wherein the p-type contact layer is formed of one selected from an InGaAs layer and an InP layer.

### Claim 4 (depends on 2)

The light-receiving device according to claim 2, wherein the concentration adjusting layer is formed of at least one selected from an InGaAs layer and an InP layer.

### Claim 5 (depends on 1)

The light-receiving device according to claim 1, wherein the p-type region has a concentration of the p-type impurity of 5×1016 cm−3 or less at the boundary between the light-receiving layer and the cap layer disposed on the light-receiving layer.

### Claim 6 (depends on 1)

The light-receiving device according to claim 1, wherein the light-receiving layer includes an undoped type-II multi-quantum well structure.

### Claim 7 (depends on 6)

The light-receiving device according to claim 6, wherein the substrate is made of InP, and
the type-II multi-quantum well structure of the light-receiving layer includes InGaAs layers and GaAsSb layers alternately stacked.

### Claim 8 (depends on 6)

The light-receiving device according to claim 6, wherein the type-II multi-quantum well structure of the light-receiving layer includes GaSb layers and InAs layers alternately stacked.

### Claim 9

A method for producing a light-receiving device, the method comprising the steps of:
growing a light-receiving layer on a substrate, the light-receiving layer having an undoped multi-quantum well structure;
growing a cap layer on the light-receiving layer, the cap layer including a p-type semiconductor layer doped with a p-type impurity;
forming a mesa structure by etching the cap layer, the mesa structure being defined by a trench surrounding the mesa;
after the step of forming the mesa structure, forming a protective film on an upper surface and a side surface of the mesa structure; and
after the step of forming the protective film, forming a p-n junction in the light-receiving layer or at the boundary between the light-receiving layer and the cap layer by annealing with the upper surface and the side surface of the mesa structure covered with the protective film at a predetermined temperature,
wherein, in the step of forming the mesa structure, the trench reaches the vicinity of an upper surface of the light-receiving layer, and
in the step of forming the p-n junction, the p-type impurity in the p-type semiconductor layer is diffused from the cap layer in the mesa structure to the light-receiving layer.

### Claim 10 (depends on 9)

The method according to claim 9, wherein the cap layer includes a concentration adjusting layer formed on the light-receiving layer and a p-type contact layer formed on the concentration adjusting layer, the p-type contact layer being doped with the p-type impurity,
the concentration adjusting layer is not doped or is doped with a p-type or an n-type impurity at a lower concentration than that of the p-type contact layer, and
in the step of forming the p-n junction, the p-type impurity is diffused from the p-type contact layer in the mesa structure to the light-receiving layer through the concentration adjusting layer.

### Claim 11 (depends on 9)

The method according to claim 9, wherein, in the step of growing the cap layer, the p-type semiconductor layer in the cap layer is grown while the p-type impurity is doped with a concentration gradually or stepwise increased with the lapse of growth time from the beginning of the growth.

### Claim 12 (depends on 9)

The method according to claim 9, wherein the light-receiving layer and the cap layer are grown at a growth temperature of 425° C. to 575° C. by a metal-organic vapor phase epitaxy method using metal-organic compounds for a III group source material and a V group source material.

### Claim 13 (depends on 9)

The method according to claim 9, wherein the light-receiving layer includes an undoped type-II multi-quantum well structure.

### Claim 14

A method for producing a light-receiving device, the method comprising the steps of:
growing a light-receiving layer on a substrate, the light-receiving layer having an undoped multi-quantum well structure;
forming a selective growth mask on the light-receiving layer, the selective growth mask including an opening through which the light-receiving layer is exposed;
selectively growing a concentration adjusting layer and a p-type contact layer, in that order, on the light-receiving layer using the selective growth mask, the p-type contact layer being doped with a p-type impurity; and
forming a p-n junction in the light-receiving layer or at the boundary between the light-receiving layer and the concentration adjusting layer,
wherein the concentration adjusting layer is not doped or is doped with a p-type or an n-type impurity at a lower concentration than that of the p-type contact layer, and
in the step of forming the p-n junction, the p-type impurity doped in the p-type contact layer is diffused to the light-receiving layer through the concentration adjusting layer during growing the p-type contact layer.