# US 8,569,153 B2 · Method and system for carbon doping control in gallium nitride based devices

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- Number: US 8,569,153 B2
- Document ID: US8569153B2
- Status: Granted
- Kind: B2
- Application number: 13/307,108
- Filed: 2011-11-30
- Published: 2013-05-30
- Granted: 2013-10-29
- Earliest claimed: 2011-11-30
- Assignees: Avogy, Inc.
- Applicants: David P. Bour; Thomas R. Prunty; Linda Romano; Richard J. Brown; Isik C. Kizilyalli; Hui Nie
- Inventors: David P. Bour; Thomas R. Prunty; Linda Romano; Richard J. Brown; Isik C. Kizilyalli; Hui Nie
- Web page: https://patentgrep.com/patent/US8569153B2

## CPC

- H10P 14/27: {using selective deposition, e.g. simultaneous growth of monocrystalline and non-monocrystalline semiconductor materials}
- H10D 8/051: {of Schottky diodes}
- H10D 30/01: Manufacture or treatment
- H10D 62/8503: {Nitride Group III-V materials, e.g. AlN or GaN}
- H10D 62/854: further characterised by the dopants
- 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 14/3416: {Nitrides}
- H10P 14/3442: {N-type}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

A method of growing an n-type III-nitride-based epitaxial layer includes providing a substrate in an epitaxial growth reactor, forming a masking material coupled to a portion of a surface of the substrate, and flowing a first gas into the epitaxial growth reactor. The first gas includes a group III element and carbon. The method further comprises flowing a second gas into the epitaxial growth reactor. The second gas includes a group V element, and a molar ratio of the group V element to the group III element is at least 5,000. The method also includes growing the n-type III-nitride-based epitaxial layer.

## Claims

### Claim 1

A method of growing an n-type III-nitride-based epitaxial layer, the method comprising:
providing a substrate in an epitaxial growth reactor;
forming a masking material coupled to a portion of a surface of the substrate;
flowing a first gas into the epitaxial growth reactor, wherein the first gas includes a group III element and carbon; and
flowing a second gas into the epitaxial growth reactor, wherein the second gas includes a group V element, wherein a molar ratio of the group V element to the group III element is at least 5,000; and
growing the n-type III-nitride-based epitaxial layer.

### Claim 2 (depends on 1)

The method of claim 1 wherein growing the n-type III-nitride-based epitaxial layer comprises a selective regrowth.

### Claim 3 (depends on 1)

The method of claim 1 wherein the masking material comprises an oxide.

### Claim 4 (depends on 1)

The method of claim 1 wherein the first gas comprises at least one of tri-methyl gallium or tri-ethyl gallium.

### Claim 5 (depends on 1)

The method of claim 1 wherein the second gas comprises ammonia.

### Claim 6 (depends on 1)

The method of claim 1 wherein the n-type III-nitride-based epitaxial layer has a carbon concentration less than 1×1016 cm−3.

### Claim 7 (depends on 1)

The method of claim 1 wherein a growth rate of the n-type III-nitride-based epitaxial layer is between 1 μm/hr and 2 μm/hr.

### Claim 8 (depends on 1)

The method of claim 1 wherein the n-type III-nitride-based epitaxial layer comprises a channel region of a vertical JFET.

### Claim 9

A method of manufacturing a vertical JFET, the method comprising:
providing an n-type GaN-based substrate having a surface and a first electrical contact opposing the surface;
forming an epitaxial n-type drift layer coupled to at least a portion of the n-type GaN-based substrate and operable to conduct current in a direction substantially orthogonal to the surface;
forming a masking material coupled to a portion of the epitaxial n-type drift layer;
forming an n-type channel structure coupled to the epitaxial n-type drift layer, wherein gases including a group V element and a group III element used in forming the n-type channel structure are adjusted such that a molar ratio of the group V element to the group III element is at least 5,000;
forming an n-type contact layer coupled to the n-type channel structure and substantially parallel to the surface;
forming a second electrical contact electrically coupled to the n-type contact layer;
forming a p-type gate region electrically coupled to the n-type channel structure; and
forming a third electrical contact electrically coupled to the p-type gate region.

### Claim 10 (depends on 9)

The method of claim 9 wherein a concentration of carbon in the n-type channel structure is less than 1×1016 cm−3.

### Claim 11 (depends on 9)

The method of claim 9 wherein the molar ratio of the group V element to the group III element is at least 10,000.

### Claim 12 (depends on 9)

The method of claim 9 wherein a thickness of the epitaxial n-type drift layer is greater than 1 μm.

### Claim 13 (depends on 9)

The method of claim 9 wherein a concentration of carbon in the epitaxial n-type drift layer is less than 1×1016 cm−3.

### Claim 14 (depends on 9)

The method of claim 9 wherein a growth rate of the n-type channel structure is between 1 μm/hr and 2 μm/hr.

### Claim 15

A method of growing an n-type GaN-based epitaxial layer, the method comprising:
placing a GaN-based substrate in an MOCVD reactor;
forming an oxide coupled to a portion of a surface of the GaN-based substrate;
flowing a gas containing gallium and carbon into the MOCVD reactor; and
flowing a gas containing nitrogen into the MOCVD reactor, wherein a molar ratio of nitrogen to gallium is at least 5,000; and
growing the n-type GaN-based epitaxial layer.

### Claim 16 (depends on 15)

The method of claim 15 wherein the gas containing nitrogen comprises at least one of ammonia or cracked ammonia.

### Claim 17 (depends on 15)

The method of claim 15 wherein the gas containing gallium comprises at least one of tri-methyl gallium, tri-ethyl gallium, cracked tri-methyl gallium, or cracked tri-ethyl gallium.

### Claim 18 (depends on 15)

The method of claim 15 wherein the n-type GaN-based epitaxial layer has a carbon concentration less than 1×1016 cm−3.

### Claim 19 (depends on 15)

The method of claim 15 wherein a growth rate of the n-type GaN-based epitaxial layer is between 1 μm/hr and 2 μm/hr.

### Claim 20 (depends on 15)

The method of claim 15 wherein the n-type GaN-based epitaxial layer comprises a channel region of a vertical JFET.

### Claim 21 (depends on 15)

The method of claim 15 wherein the GaN-based substrate comprises an n-type GaN substrate.