# US 8,772,758 B2 · Suppression of inclined defect formation and increase in critical thickness by silicon doping on non-c-plane (Al,Ga,In)N

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- Number: US 8,772,758 B2
- Document ID: US8772758B2
- Status: Granted
- Kind: B2
- Application number: 13/470,598
- Filed: 2012-05-14
- Published: 2012-11-15
- Granted: 2014-07-08
- Earliest claimed: 2011-05-13
- Assignees: The Regents of the University of California
- Applicants: Matthew T. Hardy; Po Shan Hsu; Steven P. DenBaars; James S. Speck; Shuji Nakamura
- Inventors: Matthew T. Hardy; Po Shan Hsu; Steven P. DenBaars; James S. Speck; Shuji Nakamura
- Web page: https://patentgrep.com/patent/US8772758B2

## CPC

- H10P 14/3416: {Nitrides}
- H10P 14/2908: {Nitrides}
- H10P 14/2926: {Crystal orientations}
- H10P 14/3216: {Nitrides}
- H10P 14/3256: {Microstructure}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

A method for fabricating a III-nitride based semiconductor device, including (a) growing one or more buffer layers on or above a semi-polar or non-polar GaN substrate, wherein the buffer layers are semi-polar or non-polar III-nitride buffer layers; and (b) doping the buffer layers so that a number of crystal defects in III-nitride device layers formed on or above the doped buffer layers is not higher than a number of crystal defects in III-nitride device layers formed on or above one or more undoped buffer layers. The doping can reduce or prevent formation of misfit dislocation lines and additional threading dislocations. The thickness and/or composition of the buffer layers can be such that the buffer layers have a thickness near or greater than their critical thickness for relaxation. In addition, one or more (AlInGaN) or III-nitride device layers can be formed on or above the buffer layers.

## Claims

### Claim 1

A method for fabricating a Group III-nitride based semiconductor device, comprising:
(a) growing one or more buffer layers on or above a semi-polar or non-polar GaN substrate, wherein the buffer layers are semi-polar or non-polar Group III-nitride buffer layers; and
(b) doping the buffer layers so that a number of crystal defects in Group III-nitride device layers formed on or above the doped buffer layers is not higher than a number of crystal defects in Group III-nitride device layers formed on or above one or more undoped buffer layers.

### Claim 2 (depends on 1)

The method of claim 1, wherein the buffer layers are doped with a doping concentration of more than 3×1018 cm−3.

### Claim 3 (depends on 1)

The method of claim 1, wherein the buffer layers are doped with Silicon (Si).

### Claim 4 (depends on 1)

The method of claim 1, further comprising forming one or more Group III-nitride device layers above the buffer layers.

### Claim 5 (depends on 1)

The method of claim 1, wherein the Group III-nitride device layers are coherently grown on or above the doped buffer layers.

### Claim 6 (depends on 1)

The method of claim 1, wherein one or more of the Group III-nitride device layers formed on or above the doped buffer layers, including an active region, have a threading dislocation density of 107 cm−2 or less.

### Claim 7 (depends on 6)

The method of claim 6, wherein an indium composition of one or more of the Group III-nitride device layers formed on or above the doped buffer layers, including the active region, is at least 30%, or sufficient for the device to emit light having a peak intensity at a wavelength in a green wavelength range or longer.

### Claim 8 (depends on 7)

The method of claim 7, wherein the Group III-nitride device layers formed on or above the doped buffer layers comprise one or more waveguiding layers or one or more cladding layers, or the one or more waveguiding layers and the one or more cladding layers.

### Claim 9 (depends on 1)

The method of claim 1, wherein the doping reduces or prevents formation of misfit dislocations with line directions inclined with respect to an in-plane m- or a-direction of the Group III-nitride device layers formed on or above the doped buffer layers.

### Claim 10 (depends on 9)

The method of claim 9, where the doping prevents formation of additional threading dislocations during growth of the buffer layers and the Group III-nitride device layers on or above the doped buffer layers.

### Claim 11 (depends on 1)

The method of claim 1, wherein the doping reduces or prevents formation of misfit dislocation lines resulting from c-plane slip where the line direction is parallel to an in-plane m- or a-direction of the Group III-nitride device layers formed on or above the doped buffer layers.

### Claim 12 (depends on 1)

The method of claim 1, wherein the doping and a thickness, a composition, or the thickness and the composition, of the doped buffer layers are such that the doped buffer layers have a thickness near or greater than their critical thickness for relaxation.

### Claim 13 (depends on 1)

The method of claim 1, further comprising increasing or maximizing a critical thickness of the buffer layers by the doping, or wherein the doping is such that the critical thickness is thicker as compared to without the doping.

### Claim 14 (depends on 1)

A device fabricated according to the method claim 1.

### Claim 15 (depends on 1)

The method of claim 1, wherein the buffer layers comprise InGaN.

### Claim 16 (depends on 1)

The method of claim 1, wherein the buffer layers comprise AlGaN.

### Claim 17

A Group III-nitride based semiconductor device structure, comprising:
one or more buffer layers on or above a semi-polar or non-polar GaN substrate, wherein:
the buffer layers are semi-polar or non-polar Group III-nitride buffer layers, and
a doping concentration in the buffer layers is optimized such that a number of crystal defects in Group III-nitride device layers formed on or above the doped buffer layers is not higher than a number of crystal defects in Group III-nitride device layers formed on or above one or more undoped buffer layers.

### Claim 18 (depends on 17)

The device structure of claim 17, wherein the doping concentration is more than 3×1018 cm−3.

### Claim 19 (depends on 17)

The device structure of claim 17, wherein the buffer layers are doped with Silicon (Si).

### Claim 20 (depends on 17)

The device structure of claim 17, further comprising one or more Group III-nitride device layers formed above the buffer layers.

### Claim 21 (depends on 17)

The device structure of claim 17, wherein the Group III-nitride device layers are coherently grown on or above the doped buffer layers.

### Claim 22 (depends on 17)

The device structure of claim 17, wherein one or more of the Group III-nitride device layers formed on or above the doped buffer layers, including an active region, have a threading dislocation density of 107 cm−2 or less.

### Claim 23 (depends on 22)

The device structure of claim 22, wherein an indium composition of one or more of the Group III-nitride device layers formed on or above the doped buffer layers, including the active region, is at least 30% or sufficient for the device to emit light having a peak intensity at a wavelength in a green wavelength range or longer.

### Claim 24 (depends on 23)

The device structure of claim 23, wherein the Group III-nitride device layers formed on or above the doped buffer layers comprise one or more waveguiding layers or one or more cladding layers, or the one or more waveguiding layers and the one or more cladding layers.

### Claim 25 (depends on 17)

The device structure of claim 17, wherein the doping concentration reduces or prevents formation of misfit dislocations with line directions inclined with respect to an in-plane m- or a-direction of the Group III-nitride device layers formed on or above the doped buffer layers.

### Claim 26 (depends on 25)

The device structure of claim 25, where the doping concentration prevents formation of additional threading dislocations in the Group III-nitride device layers on or above the doped buffer layers.

### Claim 27 (depends on 17)

The device structure of claim 17, wherein the doping concentration reduces or prevents formation of misfit dislocation lines resulting from c-plane slip where the line direction is parallel to the in-plane m- or a-direction.

### Claim 28 (depends on 17)

The device structure of claim 17, wherein the doping concentration and a thickness or composition of the doped buffer layers is such that the doped buffer layers are near or greater than their critical thickness for relaxation.

### Claim 29 (depends on 17)

The device structure of claim 17, wherein the buffer layers comprise InGaN.

### Claim 30 (depends on 17)

The device structure of claim 17, wherein the buffer layers comprise AlGaN.

### Claim 31 (depends on 17)

The device structure of claim 17, wherein the Group III-nitride device layers formed on or above the doped buffer layers are the layers of a laser diode (LD), light emitting diode (LED), solar cell, or transistor.

### Claim 32 (depends on 17)

The device structure of claim 17, wherein the Group III-nitride device layers formed on or above the doped buffer layers are layers of a laser diode, including cladding layers, waveguiding layers, and an active region.