# US 8,541,253 B2 · III-nitride semiconductor laser device, and method of fabricating the III-nitride semiconductor laser device

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- Number: US 8,541,253 B2
- Document ID: US8541253B2
- Status: Granted
- Kind: B2
- Application number: 13/416,844
- Filed: 2012-03-09
- Published: 2012-08-09
- Granted: 2013-09-24
- Earliest claimed: 2009-09-30
- Assignees: Sumitomo Electric Industries, Ltd.
- Applicants: Yusuke Yoshizumi; Yohei Enya; Takashi Kyono; Masahiro Adachi; Shinji Tokuyama; Takamichi Sumitomo; Masaki Ueno; Takatoshi Ikegami; Koji Katayama; Takao Nakamura
- Inventors: Yusuke Yoshizumi; Yohei Enya; Takashi Kyono; Masahiro Adachi; Shinji Tokuyama; Takamichi Sumitomo; Masaki Ueno; Takatoshi Ikegami; Koji Katayama; Takao Nakamura
- Web page: https://patentgrep.com/patent/US8541253B2

## CPC

- H01S 5/320275: {semi-polar orientation}
- B82Y 20/00: Nanooptics, e.g. quantum optics or photonic crystals
- H01S 5/0287: {Facet reflectivity}
- H01S 5/0202: {Cleaving}
- H01S 5/028: Coatings {; Treatment of the laser facets, e.g. etching, passivation layers or reflecting layers}
- H01S 5/2009: {by using electron barrier layers}
- H01S 5/2031: {characterized by special waveguide layers, e.g. asymmetric waveguide layers or defined bandgap discontinuities}
- H01S 5/2201: {in a specific crystallographic orientation}
- H01S 5/3213: {asymmetric clading layers}
- H01S 5/34333: {with a well layer based on Ga(In)N or Ga(In)P, e.g. blue laser}
- H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES

## Abstract

A method of fabricating a III-nitride semiconductor laser device includes: preparing a substrate with a semipolar primary surface, the semipolar primary surface including a hexagonal III-nitride semiconductor; forming a substrate product having a laser structure, an anode electrode, and a cathode electrode, the laser structure including a substrate and a semiconductor region, and the semiconductor region being formed on the semipolar primary surface; after forming the substrate product, forming first and second end faces; and forming first and second dielectric multilayer films for an optical cavity of the nitride semiconductor laser device on the first and second end faces, respectively.

## Claims

### Claim 1

A method of fabricating a III-nitride semiconductor laser device, comprising the steps of:
preparing a substrate with a semipolar primary surface, the semipolar primary surface comprising a hexagonal III-nitride semiconductor;
forming a substrate product having a laser structure, an anode electrode, and a cathode electrode, the laser structure comprising a substrate and a semiconductor region, and the semiconductor region being formed on the semipolar primary surface;
after forming the substrate product, forming first and second end faces; and
forming first and second dielectric multilayer films for an optical cavity of the nitride semiconductor laser device on the first and second end faces, respectively,
the first and second end faces intersecting with a reference plane, the reference plane being defined by a normal axis to the semipolar primary surface and any one crystal axis of a- and m-axes of the hexagonal III-nitride semiconductor,
the semiconductor region comprising a first cladding layer of a first conductivity type gallium nitride-based semiconductor, a second cladding layer of a second conductivity type gallium nitride-based semiconductor, and an active layer, and the active layer being provided between the first cladding layer and the second cladding layer,
the first cladding layer, the second cladding layer, and the active layer being arranged in a direction of the normal axis,
the active layer comprising a gallium nitride-based semiconductor layer,
the semipolar primary surface of the substrate being inclined at an angle in a range of not less than 45 degrees and not more than 80 degrees and of not less than 100 degrees and not more than 135 degrees with respect to a plane perpendicular to a c+ axis vector, and the c+ axis vector indicating a direction of the <0001> axis of the nitride semiconductor,
the c+ axis vector making an acute angle with a waveguide vector, and the waveguide vector indicating a direction from the second end face to the first end face, and
a thickness of the second dielectric multilayer film being smaller than a thickness of the first dielectric multilayer film.

### Claim 2 (depends on 1)

The method according to claim 1, further comprising a step of, prior to forming the first and second dielectric multilayer films, determining plane orientations of the first and second end faces.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the step of forming the first and second end faces comprises the steps of:
scribing a first surface of the substrate product; and
breaking the substrate product by press against a second surface of the substrate product to form a laser bar having the first and second end faces,
the first and second end faces of the laser bar being formed by the breaking,
the first surface being opposite to the second surface,
the semiconductor region being provided between the first surface and the substrate, and
each of the first and second end faces of the laser bar being included in a fractured face, and the fractured face extending from the first surface to the second surface and being formed by the breaking.

### Claim 4 (depends on 1)

The method according to claim 1, wherein a c-axis of the III-nitride semiconductor is inclined toward a direction of the m-axis of the nitride semiconductor.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the primary surface of the substrate is inclined in a range of not less than −4 degrees and not more than +4 degrees with respect to any one of {10-11}, {20-21}, {20-2-1}, and {10-1-1} planes.

### Claim 6 (depends on 1)

The method according to claim 1, wherein a c-axis of the III-nitride semiconductor is inclined toward a direction of an a-axis of the nitride semiconductor.

### Claim 7 (depends on 1)

The method according to claim 1, wherein the primary surface of the substrate is inclined in the range of not less than −4 degrees and not more than +4 degrees from any one of {11-22}, {11-21}, {11-2-1}, and {11-2-2} planes.

### Claim 8 (depends on 1)

The method according to claim 1, wherein formation of the active layer comprises a step of growing a well layer of a strained gallium nitride-based semiconductor, and the strained gallium nitride-based semiconductor contains indium as a constituent element.

### Claim 9 (depends on 1)

The method according to claim 1, wherein the active layer is provided to generate light at a wavelength of 430-550 nm.

### Claim 10 (depends on 1)

The method according to claim 1, wherein the III-nitride semiconductor comprises GaN.

### Claim 11 (depends on 1)

The method according to claim 1, wherein the first dielectric multilayer film has a dielectric layer, and the a dielectric layer in the first dielectric multilayer film is formed using at least one of silicon oxide, silicon nitride, silicon oxynitride, titanium oxide, titanium nitride, titanium oxynitride, zirconium oxide, zirconium nitride, zirconium oxynitride, zirconium fluoride, tantalum oxide, tantalum nitride, tantalum oxynitride, hafnium oxide, hafnium nitride, hafnium oxynitride, hafnium fluoride, aluminum oxide, aluminum nitride, aluminum oxynitride, magnesium fluoride, magnesium oxide, magnesium nitride, magnesium oxynitride, calcium fluoride, barium fluoride, cerium fluoride, antimony oxide, bismuth oxide, and gadolinium oxide, and
wherein the second dielectric multilayer film has a dielectric layer, and the dielectric layer in the second dielectric multilayer film is formed using at least one selected from silicon oxide, silicon nitride, silicon oxynitride, titanium oxide, titanium nitride, titanium oxynitride, zirconium oxide, zirconium nitride, zirconium oxynitride, zirconium fluoride, tantalum oxide, tantalum nitride, tantalum oxynitride, hafnium oxide, hafnium nitride, hafnium oxynitride, hafnium fluoride, aluminum oxide, aluminum nitride, aluminum oxynitride, magnesium fluoride, magnesium oxide, magnesium nitride, magnesium oxynitride, calcium fluoride, barium fluoride, cerium fluoride, antimony oxide, bismuth oxide, and gadolinium oxide.