# US 10,121,656 B2 · Buffer layers having composite structures

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- Number: US 10,121,656 B2
- Document ID: US10121656B2
- Status: Granted
- Kind: B2
- Application number: 15/432,226
- Filed: 2017-02-14
- Published: 2017-09-07
- Granted: 2018-11-06
- Earliest claimed: 2016-03-02
- Assignees: Xiamen Changelight Co., Ltd.
- Applicants: Xiamen Changelight Co., Ltd.
- Inventors: Kaixuan Chen; Wei Jiang; Zhiwei Lin; Xiangjing Zhuo; Tianzu Fang; Yang Wang; Jichu Tong
- Web page: https://patentgrep.com/patent/US10121656B2

## CPC

- H10P 14/3252: {Alternating layers, e.g. superlattice}
- C30B 25/183: {being provided with a buffer layer, e.g. a lattice matching layer}
- C30B 29/406: {Gallium nitride}
- H10F 77/169: Thin semiconductor films on metallic or insulating substrates
- H10H 20/815: having stress relaxation structures, e.g. buffer layers
- H10P 14/24: using chemical vapour deposition [CVD]
- H10P 14/3216: {Nitrides}
- H10P 14/3218: {Phosphides}
- H10P 14/3221: {Arsenides}
- H10P 14/3222: {Antimonides}
- H10P 14/3251: {consisting of three or more layers}
- H10P 14/3416: {Nitrides}
- H10H 20/0137: {the light-emitting regions comprising nitride materials}
- H10H 20/825: containing nitrogen, e.g. GaN
- H10P 14/3214: {being Group IIIA-VA semiconductors}
- Y02E 10/50: Photovoltaic [PV] energy
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- C30B: SINGLE-CRYSTAL GROWTH (by using ultra-high pressure, e.g. for the formation of diamonds, B01J3/06); UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL (zone-refining of metals or alloys C22B); PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (casting of metals, casting of other substances by the same processes or devices B22D; working of plastics B29; modifying the physical structure of metals or alloys C21D, C22F); SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (for producing semiconductor devices or parts thereof H10); APPARATUS THEREFOR
- 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

Disclosed is a wafer or a material stack for semiconductor-based optoelectronic or electronic devices that minimizes or reduces misfit dislocation, as well as a method of manufacturing such wafer of material stack. A material stack according to the disclosed technology includes a substrate; a basis buffer layer of a first material disposed above the substrate; and a plurality of composite buffer layers disposed above the basis buffer layer sequentially along a growth direction. The growth direction is from the substrate to a last composite buffer layer of the plurality of composite buffer layers. Each composite buffer layer except the last composite buffer layer includes a first buffer sublayer of the first material, and a second buffer sublayer of a second material disposed above the first buffer sublayer. The thicknesses of the first buffer sublayers of the composite buffer layers decrease along the growth direction.

## Claims

### Claim 1

A material stack for semiconductor-based optoelectronic or electronic devices, comprising:
a substrate;
a basis buffer layer of a first material disposed above the substrate; and
a plurality of composite buffer layers disposed above the basis buffer layer sequentially along a growth direction from the substrate to a last composite buffer layer of the plurality of composite buffer layers, each composite buffer layer except the last composite buffer layer including:
a first buffer sublayer of the first material, and
a second buffer sublayer of a second material disposed above the first buffer sublayer;
wherein thicknesses of the first buffer sublayers of the composite buffer layers decrease along the growth direction.

### Claim 2 (depends on 1)

The material stack of claim 1, wherein thicknesses of the second buffer sublayers of the composite buffer layers increase along the growth direction.

### Claim 3 (depends on 1)

The material stack of claim 1, wherein the basis buffer layer of the first material has a relaxed lattice constant for the first material, and the first buffer sublayer of a first composite buffer layer among the composite buffer layers has the relaxed lattice constant for the first material.

### Claim 4 (depends on 1)

The material stack of claim 1, wherein the last composite buffer layer includes a buffer sublayer of the second material and does not include a buffer sublayer of the first material, and the buffer sublayer of the second material of the last composite buffer layer has a relaxed lattice constant for the second material.

### Claim 5 (depends on 1)

The material stack of claim 1, wherein the first buffer sublayers and the second buffer sublayers of the composite buffer layers contain substantially no misfit dislocation due to lattice mismatch between the first material and the second material.

### Claim 6 (depends on 1)

The material stack of claim 1, wherein first material is aluminum nitride (AlN) and the second material is gallium nitride (GaN).

### Claim 7 (depends on 6)

The material stack of claim 6, wherein the plurality of composite buffer layers have the same thickness.

### Claim 8 (depends on 7)

The material stack of claim 7, wherein the thickness of the first buffer sublayer of each composite buffer layer is less than a critical thickness of the first material at which stress is fully released by misfit dislocation.

### Claim 9 (depends on 7)

The material stack of claim 7, wherein thickness of the second buffer sublayer of each composite buffer layer is less than a critical thickness of the second material at which stress is fully released by misfit dislocation.

### Claim 10 (depends on 7)

The material stack of claim 7, further comprising:
one or more functional layers above the last composite buffer layer, the one or more functional layers including a conductive layer, an active layer, or an electron-blocking layer.

### Claim 11 (depends on 1)

The material stack of claim 1, wherein the first material is a nitride compound, an alloy of nitride compounds, an arsenide compound, an alloy of arsenide compounds, a phosphide compound, an alloy of phosphide compounds, an antimonide compound, an alloy of antimonide compounds, a ternary alloy of group III elements and group V elements, or a quaternary alloy of group III elements and group V elements; and the second material is a nitride compound, an alloy of nitride compounds, an arsenide compound, an alloy of arsenide compounds, a phosphide compound, an alloy of phosphide compounds, an antimonide compound, an alloy of antimonide compounds, a ternary alloy of group III elements and group V elements, or a quaternary alloy of group III elements and group V elements.

### Claim 12

An optoelectronic or electronic device, comprising:
a substrate;
a basis buffer layer of a first material disposed above the substrate; and
a plurality of composite buffer layers disposed above the basis buffer layer sequentially along a growth direction from the substrate to a last composite buffer layer of the plurality of composite buffer layers, each specific composite buffer layer except the last composite buffer layer including:
a first buffer sublayer of the first material, and
a second buffer sublayer of a second material disposed above the first buffer sublayer, the specific composite buffer layer having a thickness ratio that is a ratio of a thickness of the second buffer sublayer to a thickness of the first buffer sublayer;
wherein the thickness ratios of the composite buffer layers increase along the growth direction.

### Claim 13 (depends on 12)

The device of claim 12, wherein lattice constants of the second buffer sublayers of the composite buffer layers increase along the growth direction.

### Claim 14 (depends on 12)

The device of claim 12, wherein the first buffer sublayer of a first composite buffer layer among the composite buffer layers has a relaxed lattice constant for the first material, and the second buffer sublayer of the first composite buffer layer has a lattice constant that is between the relaxed lattice constant for the first material and a relaxed lattice constant for the second material.

### Claim 15 (depends on 12)

The device of claim 12, wherein the last composite buffer layer includes a buffer sublayer of the second material and does not include a buffer sublayer of the first material, and the buffer sublayer of the second material of the last composite buffer layer has a relaxed lattice constant for the second material.

### Claim 16 (depends on 12)

The device of claim 12, wherein the thickness of the first buffer sublayer of each composite buffer layer is less than a critical thickness of the first material at which stress is fully released by misfit dislocation, and the thickness of the second buffer sublayer of each composite buffer layer is less than a critical thickness of the second material at which stress is fully released by misfit dislocation.

### Claim 17 (depends on 12)

The device of claim 12, wherein the thicknesses of the first buffer sublayers of the composite buffer layers decrease along the growth direction.

### Claim 18

A wafer for semiconductor-based optoelectronic or electronic devices, comprising:
a substrate;
a basis buffer layer of a first material disposed above the substrate; and
a plurality of composite buffer layers disposed above the basis buffer layer sequentially along a growth direction from the substrate to a last composite buffer layer of the plurality of composite buffer layers, each composite buffer layer except the last composite buffer layer including:
a first buffer sublayer of the first material, and
a second buffer sublayer of a second material disposed above the first buffer sublayer;
wherein lattice constants of the second buffer sublayers of the composite buffer layers increase along the growth direction.

### Claim 19 (depends on 18)

The wafer of claim 18, wherein the last composite buffer layer includes a buffer sublayer of the second material and does not include a buffer sublayer of the first material, and the buffer sublayer of the second material of the last composite buffer layer has a relaxed lattice constant for the second material.

### Claim 20 (depends on 18)

The wafer of claim 18, wherein lattice constants of the first buffer sublayers of the composite buffer layers increase along the growth direction.