# US 7,745,315 B1 · Highly aligned vertical GaN nanowires using submonolayer metal catalysts

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- Number: US 7,745,315 B1
- Document ID: US7745315B1
- Status: Granted
- Kind: B1
- Application number: 11/866,684
- Filed: 2007-10-03
- Granted: 2010-06-29
- Earliest claimed: 2007-10-03
- Assignees: Sandia Corporation
- Inventors: George T. Wang; Qiming Li; J. Randall Creighton
- Web page: https://patentgrep.com/patent/US7745315B1

## CPC

- H10P 14/3416: {Nitrides}
- C30B 11/12: Vaporous components, e.g. vapour-liquid-solid-growth
- C30B 25/00: Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
- C30B 29/406: {Gallium nitride}
- C30B 29/60: characterised by shape
- H10P 14/24: using chemical vapour deposition [CVD]
- H10P 14/271: {characterised by the preparation of substrate for selective deposition}
- H10P 14/274: {using seed materials}
- H10P 14/279: {Vapour-liquid-solid growth}
- H10P 14/2921: {being crystalline insulating materials}
- H10P 14/3462: {Nanowires}
- Y10S 977/762: Nanowire or quantum wire, i.e. axially elongated structure having two dimensions of 100 nm or less
- Y10S 977/816: III-N based compounds, e.g. AlxGayInzN
- Y10S 977/891: Vapor phase deposition
- 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
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

A method for forming vertically oriented, crystallographically aligned nanowires (nanocolumns) using monolayer or submonolayer quantities of metal atoms to form uniformly sized metal islands that serve as catalysts for MOCVD growth of Group III nitride nanowires.

## Claims

### Claim 1

A method for fabricating vertically oriented nanowires on a substrate, the method comprising:
depositing up to approximately a monolayer of catalyst metal atoms on a surface of a crystallographic template substrate;
heating the crystallographic template substrate to induce surface diffusion of the catalyst metal atoms to form a plurality of metal nanoclusters; and
reacting gallium atom precursor molecules and nitrogen precursor molecules at the metal nanoclusters to form vertically oriented single-crystal gallium nitride nanowires epitaxially aligned with the crystallographic template substrate, wherein the ratio of nitrogen precursor molecules to gallium atom precursor molecules is greater than 1.

### Claim 2 (depends on 1)

The method of claim 1, wherein a submonolayer of catalyst metal atoms is deposited using a metal evaporation technique and wherein a nominal thickness of catalyst metal is less than or equal to approximately 3 Å.

### Claim 3 (depends on 1)

The method of claim 1, wherein the step of heating the crystallographic template substrate is performed under a reducing atmosphere.

### Claim 4 (depends on 1)

The method of claim 1, wherein the gallium atom precursor molecules are selected from the group consisting of trimethylgallium, triethylgallium, gallium-containing hydrocarbon compounds, gallium, gallium oxide, and gallium nitride.

### Claim 5 (depends on 1)

The method of claim 1, wherein the nitrogen precursor molecules are selected from the group consisting of ammonia, and nitrogen.

### Claim 6 (depends on 1)

The method of claim 1, wherein the catalyst metal atoms are selected from the group consisting of Ni, Au, Pt, Ga, In, Co, and Fe.

### Claim 7 (depends on 1)

The method of claim 1, wherein the step of reacting is performed at a temperature between approximately 650° C. and approximately 850° C.

### Claim 8 (depends on 1)

The method of claim 1, wherein the crystallographic template substrate is selected from the group consisting of r-plane sapphire and a substrate comprising a surface layer of epitaxially grown GaN.