# US 8,541,252 B2 · Abbreviated epitaxial growth mode (AGM) method for reducing cost and improving quality of LEDs and lasers

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- Number: US 8,541,252 B2
- Document ID: US8541252B2
- Status: Granted
- Kind: B2
- Application number: 12/972,418
- Filed: 2010-12-17
- Published: 2011-06-23
- Granted: 2013-09-24
- Earliest claimed: 2009-12-17
- Assignees: Lehigh University
- Applicants: Nelson Tansu; Helen M. Chan; Richard P. Vinci; Yik-Khoon Ee; Jeffrey Biser
- Inventors: Nelson Tansu; Helen M. Chan; Richard P. Vinci; Yik-Khoon Ee; Jeffrey Biser
- Web page: https://patentgrep.com/patent/US8541252B2

## CPC

- H10H 20/01335: {the light-emitting regions comprising nitride materials}
- C30B 25/183: {being provided with a buffer layer, e.g. a lattice matching layer}
- C30B 29/406: {Gallium nitride}
- H10P 14/2921: {being crystalline insulating materials}
- H10P 14/2925: {Surface structures}
- H10P 14/3216: {Nitrides}
- H10P 14/3416: {Nitrides}
- H10P 14/36: {characterised by treatments done before the formation of the materials}
- H10H 20/819: characterised by their shape, e.g. curved or truncated substrates
- H10H: INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
- 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
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

The use of an abbreviated GaN growth mode on nano-patterned AGOG sapphire substrates, which utilizes a process of using 15 nm low temperature GaN buffer and bypassing etch-back and recovery processes during epitaxy, enables the growth of high-quality GaN template on nano-patterned AGOG sapphire. The GaN template grown on nano-patterned AGOG sapphire by employing abbreviated growth mode has two orders of magnitude lower threading dislocation density than that of conventional GaN template grown on planar sapphire. The use of abbreviated growth mode also leads to significant reduction in cost of the epitaxy. The growths and characteristics of InGaN quantum wells (QWs) light emitting diodes (LEDs) on both templates were compared. The InGaN QWs LEDs grown on the nano-patterned AGOG sapphire demonstrated at least a 24% enhancement of output power enhancement over that of LEDs grown on conventional GaN templates.

## Claims

### Claim 1

A method of growing a GaN template on a substrate, comprising:
performing an abbreviated GaN growth mode (AGGM) on a patterned sapphire substrate, said AGGM including:
growing a thin low-temperature GaN layer on said substrate; and
growing a thick high-temperature GaN layer on said thin layer.

### Claim 2 (depends on 1)

The method of claim 1, wherein said growing of said thick high-temperature GaN layer is performed immediately following the growing of said thin low-temperature GaN layer.

### Claim 3 (depends on 2)

The method of claim 2, wherein said thin low-temperature GaN layer has a thickness in the range of about 10-20 nm.

### Claim 4 (depends on 3)

The method of claim 3, wherein said thick high-temperature GaN layer has a thickness in the range of about 0.10-0.30 μm.

### Claim 5 (depends on 3)

The method of claim 3, wherein said thick high-temperature GaN layer has a thickness of about 0.25 μm.

### Claim 6 (depends on 5)

The method of claim 5, wherein said low-temperature GaN layer is grown at a temperature in the range of about 525-545° C.

### Claim 7 (depends on 6)

The method of claim 6, wherein said high-temperature GaN layer is grown at a temperature in the range of about 1070-1090° C.

### Claim 8 (depends on 6)

The method of claim 6, wherein said high-temperature GaN layer is grown at a temperature of about 1080° C.

### Claim 9 (depends on 6)

The method of claim 6, wherein said patterned sapphire comprises nano-patterned sapphire etched using an AGOG process.

### Claim 10 (depends on 5)

The method of claim 5, wherein said low-temperature GaN layer is grown at a temperature of about 535° C.

### Claim 11 (depends on 2)

The method of claim 2, wherein said thin low-temperature GaN layer has a thickness of about 15 nm.

### Claim 12 (depends on 1)

The method of claim 1, wherein said patterned sapphire comprises nano-patterned sapphire.

### Claim 13

An LED formed using the following steps:
growing a GaN template on a substrate, comprising:
performing an abbreviated GaN growth mode (AGGM) on a patterned sapphire substrate, said AGGM including:
growing a thin low-temperature GaN layer on said substrate; and
growing a thick high-temperature GaN layer on said thin layer; and
growing an InGaN QWs LED on said GaN template.

### Claim 14 (depends on 13)

The method of claim 13, wherein said patterned sapphire comprises nano-patterned sapphire.