# US 8,772,829 B2 · Zinc-oxide based epitaxial layers and devices

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- Number: US 8,772,829 B2
- Document ID: US8772829B2
- Status: Granted
- Kind: B2
- Application number: 12/951,308
- Filed: 2010-11-22
- Published: 2011-03-17
- Granted: 2014-07-08
- Earliest claimed: 2008-05-21
- Assignees: Key Trans Investments, LLC
- Applicants: Bunmi T. Adekore; Jonathan Pierce
- Inventors: Bunmi T. Adekore; Jonathan Pierce
- Web page: https://patentgrep.com/patent/US8772829B2

## CPC

- C30B 25/18: characterised by the substrate
- C30B 29/16: Oxides
- H10H 20/0125: {with a substrate not being Group II-VI materials}
- H10P 14/24: using chemical vapour deposition [CVD]
- H10P 14/2914: {Oxides}
- H10P 14/2918: {being semiconductor metal oxides (Group IIB-VIA materials H10P14/2913)}
- H10P 14/2926: {Crystal orientations}
- H10P 14/3426: {Oxides}
- H10P 14/3434: {being oxide semiconductor materials (Group IIB-VIA semiconductor materials H10P14/3424)}
- H10P 14/3442: {N-type}
- H10P 14/3444: {P-type}
- H10P 14/3446: {Transition metal elements; Rare earth elements}
- 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
- H10H: INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

Methods of forming planar zinc-oxide based epitaxial layers, associated heterostructures, and devices are provided.

## Claims

### Claim 1

A method of forming a zinc-oxide based epitaxial layer, the method comprising:
providing a vicinal wurtzite substrate, wherein the vicinal wurtzite substrate includes an off-cut slice of a hexagonal crystal, and wherein the off-cut slice is offset from a principal crystallographic plane of the hexagonal crystal; and
forming a zinc-oxide based epitaxial layer on the vicinal wurtzite substrate using metalorganic chemical vapor deposition.

### Claim 2 (depends on 1)

The method of claim 1, wherein said forming the zinc-oxide based epitaxial layer on the vicinal wurtzite substrate comprises heating the vicinal wurtzite substrate to a temperature between about 400 degrees Celsius and about 900 degrees Celsius.

### Claim 3 (depends on 2)

The method of claim 2, wherein said heating the vicinal wurtzite substrate comprises heating the vicinal wurtzite substrate to a temperature between about 550 degrees Celsius and about 650 degrees Celsius.

### Claim 4 (depends on 1)

The method of claim 1, wherein the vicinal wurtzite substrate is a zinc-oxide based substrate.

### Claim 5 (depends on 1)

The method of claim 1, wherein the metalorganic chemical vapor deposition supersaturation ratio of Group VI elements to Group II elements is less than 8000.

### Claim 6 (depends on 1)

The method of claim 1, wherein the zinc-oxide based epitaxial layer further comprises at least one element selected from the group consisting of gold, silver, and potassium.

### Claim 7 (depends on 1)

The method of claim 1, wherein the vicinal wurtzite substrate has an off-cut angle from the m-plane ranging from about 2 degrees to about 15 degrees.

### Claim 8 (depends on 1)

The method of claim 1, wherein the vicinal wurtzite substrate comprises an m-plane or vicinal m-plane wurtzite substrate.

### Claim 9 (depends on 1)

The method of claim 1, wherein the vicinal wurtzite substrate comprises a Group III-nitride.

### Claim 10 (depends on 1)

The method of claim 1, further comprising slicing a hexagonal crystal of the vicinal wurtzite substrate to create a slice offset from the principal plane of the hexagonal crystal prior to said forming the zinc-oxide based epitaxial layer on the vicinal wurtzite substrate.

### Claim 11 (depends on 1)

The method of claim 1, wherein the vicinal wurtzite substrate is electrically-conductive.

### Claim 12 (depends on 1)

The method of claim 1, wherein the vicinal wurtzite substrate is electrically-insulative.

### Claim 13 (depends on 1)

The method of claim 1, wherein said forming the zinc-oxide based epitaxial layer on the vicinal wurtzite substrate comprises introducing a first gas including zinc and a second gas including oxygen to the vicinal wurtzite substrate.

### Claim 14 (depends on 1)

A device having an epitaxial layer produced according to the method of claim 1.

### Claim 15

A method of forming a zinc-oxide based epitaxial layer, the method comprising:
providing a wurtzite substrate, wherein the wurtzite substrate is a zinc-oxide based substrate and
forming a zinc-oxide based epitaxial layer on the wurtzite substrate using metalorganic chemical vapor deposition.

### Claim 16 (depends on 15)

The method of claim 15, further comprising heating the wurtzite substrate to a temperature between about 400 degrees Celsius and about 900 degrees Celsius.

### Claim 17 (depends on 15)

The method of claim 15, wherein the metalorganic chemical vapor deposition supersaturation ratio of Group VI elements to Group II elements is less than 8000.

### Claim 18 (depends on 15)

The method of claim 15, wherein the wurtzite substrate comprises a semi-polar wurtzite substrate, and wherein the semi-polar wurtzite substrate has a deposition surface parallel or substantially parallel to a plane belonging to the {11-22} or {10-12} plane families.

### Claim 19 (depends on 15)

A device having an epitaxial layer produced according to the method of claim 15.

### Claim 20

A method of forming a zinc-oxide based epitaxial layer, the method comprising:
providing a wurtzite substrate, wherein the wurtzite substrate is a zinc-oxide based substrate; and
forming a zinc-oxide based epitaxial layer on the wurtzite substrate using metalorganic chemical vapor deposition, wherein the zinc-oxide based epitaxial layer further comprises at least one element selected from the group consisting of gold, silver, and potassium.

### Claim 21

An apparatus comprising:
a vicinal wurtzite substrate, wherein the vicinal wurtzite substrate includes an off-cut slice of a hexagonal crystal, and wherein the off-cut slice is offset from a principal crystallographic plane of the hexagonal crystal; and
a zinc-oxide based epitaxial layer deposited on the vicinal wurtzite substrate.

### Claim 22 (depends on 21)

The apparatus of claim 21, wherein the vicinal wurtzite substrate comprises an m-plane or vicinal m-plane wurtzite substrate.

### Claim 23 (depends on 22)

The apparatus of claim 22, wherein the vicinal wurtzite substrate has an off-cut angle from the m-plane ranging from about 2 degrees to about 15 degrees.

### Claim 24 (depends on 21)

The apparatus of claim 21, wherein the vicinal wurtzite substrate comprises a Group III-nitride.

### Claim 25 (depends on 21)

The apparatus of claim 21, wherein the vicinal wurtzite substrate comprises a zinc-oxide based material.

### Claim 26 (depends on 21)

The apparatus of claim 21, wherein the zinc-oxide based epitaxial layer comprises at least one element selected from the group consisting of gold, silver, and potassium.

### Claim 27

An apparatus comprising:
a semi-polar wurtzite substrate, wherein the semi-polar wurtzite substrate includes an off-cut slice of a hexagonal crystal, and wherein the off-cut slice is offset from a principal crystallographic plane of the hexagonal crystal, and wherein the semi-polar wurtzite substrate comprises at least one plane selected from the group consisting of a (10-11) plane, a (10-1-1) plane, (10-12), a (10-1-2) plane, a (11-2-1) plane, a (11-21) plane, a (11-2-2) plane, and a (11-22) plane; and
a zinc-oxide based epitaxial layer deposited on the semi-polar wurtzite substrate.

### Claim 28 (depends on 27)

The apparatus of claim 27, wherein the semi-polar wurtzite substrate comprises a deposition surface parallel or substantially parallel to a plane belonging to the {11-22} or {10-12} plane families.