# US 9,039,834 B2 · Non-polar gallium nitride thin films grown by metalorganic chemical vapor deposition

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- Number: US 9,039,834 B2
- Document ID: US9039834B2
- Status: Granted
- Kind: B2
- Application number: 13/151,491
- Filed: 2011-06-02
- Published: 2011-09-22
- Granted: 2015-05-26
- Earliest claimed: 2002-04-15
- Assignees: The Regents of the University of California
- Applicants: Michael D. Craven; James Stephen Speck
- Inventors: Michael D. Craven; James Stephen Speck
- Web page: https://patentgrep.com/patent/US9039834B2

## CPC

- C30B 29/403: {AIII-nitrides}
- C30B 25/02: Epitaxial-layer growth
- C30B 25/04: Pattern deposit, e.g. by using masks
- C30B 25/105: {by irradiation or electric discharge}
- C30B 25/18: characterised by the substrate
- C30B 29/406: {Gallium nitride}
- C30B 29/605: {Products containing multiple oriented crystallites, e.g. columnar crystallites}
- H10P 14/24: using chemical vapour deposition [CVD]
- H10P 14/271: {characterised by the preparation of substrate for selective deposition}
- H10P 14/276: {Lateral overgrowth}
- H10P 14/2901: {Materials}
- H10P 14/2921: {being crystalline insulating materials}
- H10P 14/2926: {Crystal orientations}
- H10P 14/3216: {Nitrides}
- H10P 14/3416: {Nitrides}
- H10P 14/3466: {Crystal orientation}
- 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

Non-polar (11 20) a-plane gallium nitride (GaN) films with planar surfaces are grown on (1 102) r-plane sapphire substrates by employing a low temperature nucleation layer as a buffer layer prior to a high temperature growth of the non-polar (11 20) a-plane GaN thin films.

## Claims

### Claim 1

A method of growing non-polar Gallium Nitride (GaN), comprising:
growing GaN, including a non-polar a-plane GaN film, on an r-plane of a sapphire substrate using metalorganic chemical vapor deposition (MOCVD) and growth conditions including growth temperature, growth pressure, and a V/III ratio, including:
(a) depositing a GaN layer on the r-plane sapphire substrate at a first growth temperature between 400° C. and 900° C. and at atmospheric pressure; and
(b) growing the non-polar a-plane GaN film on the GaN layer at a growth pressure of 0.2 atmospheres or less, at the growth temperature higher than the first growth temperature, and using a V/III ratio of ˜1300, wherein:
the non-polar a-plane GaN film has:
a crystalline quality characterized by an on-axis Omega rocking curve having a full-width half-maximum (FWHM) of no more than 0.29° (1037″) and an off-axis Omega rocking curve having a FWHM of no more than 0.46° (1659″),
a threading dislocation density of no more than 2.6×1010 cm−2,
a threading dislocation line direction parallel to a film normal of the non-polar a-plane GaN film,
stacking faults aligned perpendicular to a c-axis of the non-polar a-plane GaN film with a stacking fault density of no more than 3.8×105 cm−1,
a top surface with a surface roughness of no more than 2.6 nanometers (nm) over an area of 5 micrometers by 5 micrometers, and
surface pitting on a sub-micron scale with a density within an order of magnitude of the threading dislocation density.

### Claim 2 (depends on 1)

The method of claim 1, wherein the non-polar a-plane GaN film comprises a coalesced film and has a wurtzite structure.

### Claim 3 (depends on 1)

The method of claim 1, wherein the non-polar a-plane GaN film has a planar top surface.

### Claim 4 (depends on 1)

The method of claim 1, wherein the non-polar a-plane GaN film is suitable for subsequent growth of device-quality III-nitride layers.

### Claim 5 (depends on 1)

The method of claim 1, wherein the non-polar a-plane GaN film has a top surface that is a device substrate or base for subsequent growth of non-polar III-nitride device layers on the top surface of the non-polar a-plane GaN film.

### Claim 6 (depends on 1)

The method of claim 1, wherein the GaN layer is
a nucleation and/or buffer layer.

### Claim 7 (depends on 1)

The method of claim 1, wherein
the growth temperature for the non-polar a-plane GaN film is about 1100° C.

### Claim 8 (depends on 1)

The method of claim 1, wherein the growth conditions and the substrate obtain the non-polar a-plane GaN film having no c-plane content.

### Claim 9 (depends on 1)

The method of claim 1, wherein the stacking fault density is at the top surface.

### Claim 10 (depends on 1)

The method of claim 1, wherein the growth conditions obtain the non-polar a-plane GaN film with a stable a-plane orientation.

### Claim 11 (depends on 1)

The method of claim 1, wherein the non-polar a-plane GaN film includes a thickness of 1.5 micrometers.

### Claim 12 (depends on 11)

The method of claim 11, wherein the GaN layer is a buffer layer and/or nucleation layer having at thickness of 1-100 nanometers.

### Claim 13 (depends on 1)

The method of claim 1, wherein growing the non-polar a-plane GaN film includes using 30 μmol per minute Ga flow and 40,000 μmol per minute N flow, thereby providing a VIII ratio of approximately 1300.