# US 2013/0156057 A1 · Semiconductor laser device and method of fabricating the same

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- Number: US 2013/0156057 A1
- Document ID: US20130156057A1
- Status: Published application
- Kind: A1
- Application number: 13/545,889
- Filed: 2012-07-10
- Published: 2013-06-20
- Earliest claimed: 2011-12-16
- Assignees: Electronics and Telecommunications Research Institute
- Inventors: In Gyoo KIM; Gyungock KIM; Sang Hoon KIM; JiHo JOO; Ki Seok JANG
- Web page: https://patentgrep.com/patent/US20130156057A1

## CPC

- H01S 5/021: {Silicon based substrates}
- H01S 5/1032: {Coupling to elements comprising an optical axis that is not aligned with the optical axis of the active region}
- H01S 5/3027: {IV compounds}
- H01S 3/0637: {Integrated lateral waveguide, e.g. the active waveguide is integrated on a substrate made by Si on insulator technology (Si/SiO2)}
- H01S 5/0205: {during growth of the semiconductor body}
- H01S 5/026: Monolithically integrated components, e.g. waveguides, monitoring photo-detectors, drivers (stabilisation of output H01S5/06)
- H01S 5/028: Coatings {; Treatment of the laser facets, e.g. etching, passivation layers or reflecting layers}
- H01S 5/125: Distributed Bragg reflector [DBR] lasers
- H01S 5/2272: {grown by a mask induced selective growth}
- 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

## Abstract

The inventive concept provides semiconductor laser devices and methods of fabricating the same. According to the method, a silicon-crystalline germanium layer for emitting a laser may be formed in a selected region by a selective epitaxial growth (SEG) method. Thus, surface roughness of both ends of a Fabry Perot cavity formed of the silicon-crystalline germanium layer may be reduced or minimized, and a cutting process and a polishing process may be omitted in the method of fabricating the semiconductor laser device.

## Claims

### Claim 1

A method of fabricating a semiconductor laser device, comprising:
forming a mask layer on a substrate;
patterning the mask layer to form a mask pattern having an opening exposing the substrate;
forming a single-crystalline germanium layer used as a Fabry Perot cavity in the opening by a selective epitaxial growth (SEG) method; and
forming an electrode on the single-crystalline germanium layer,
wherein patterning the mask layer includes:
after etching the mask layer by one of a dry etching process and a wet etching process, etching the mask layer by the other of the dry etching process and the wet etching layer for improving a surface roughness of sidewalls of the mask pattern.

### Claim 2 (depends on 1)

The method of claim 1, wherein the mask layer is formed of silicon oxide.

### Claim 3 (depends on 2)

The method of claim 2, wherein the wet etching process uses hydrofluoric acid.

### Claim 4 (depends on 1)

The method of claim 1, wherein the substrate is a silicon substrate or a silicon-on-insulator (SOI) substrate.

### Claim 5 (depends on 1)

The method of claim 1, further comprising:
forming a spacer adjacent to a first end of the Fabry Perot cavity.

### Claim 6 (depends on 5)

The method of claim 5, wherein the spacer includes metal or silicon oxide.

### Claim 7 (depends on 5)

The method of claim 5, wherein the spacer includes a grating mirror.

### Claim 8 (depends on 7)

The method of claim 7, wherein the grating mirror has a photonic band gap structure.

### Claim 9 (depends on 5)

The method of claim 5, wherein the spacer and the Fabry Perot cavity are spaced apart from each other by the mask layer.

### Claim 10 (depends on 5)

The method of claim 5, further comprising:
forming an optical coupler adjacent to a second end of the Fabry Perot cavity.

### Claim 11 (depends on 10)

The method of claim 10, wherein the optical coupler includes an optical waveguide.

### Claim 12 (depends on 11)

The method of claim 11, wherein the optical waveguide includes single-crystalline silicon or silicon nitride.

### Claim 13 (depends on 10)

The method of claim 10, wherein the mask layer fills between the first end of the Fabry Perot cavity and the spacer and between the second end of the Fabry Perot cavity and the optical coupler.

### Claim 14 (depends on 10)

The method of claim of claim 10, wherein a top surface of the Fabry Perot cavity is disposed at a height different from top surfaces of the spacer and the optical coupler.

### Claim 15

A semiconductor laser device comprising:
a substrate;
a Fabry Perot cavity of single-crystalline germanium grown by a selective epitaxial growth (SEG) method on the substrate;
a spacer adjacent to a first end of the Fabry Perot cavity and be spaced apart from the Fabry Perot cavity; and
an optical coupler adjacent to a second end of the Fabry Perot cavity and be spaced apart from the Fabry Perot cavity,
wherein a top surface of the Fabry Perot cavity is disposed at a height different from a top surface of the spacer and/or a top surface of the optical coupler.

### Claim 16 (depends on 15)

The semiconductor laser device of claim 15, wherein the spacer includes metal or silicon oxide.

### Claim 17 (depends on 15)

The semiconductor laser device of claim 15, wherein the Fabry Perot cavity has a first facet adjacent to the spacer; and
wherein the spacer includes a trench exposing the first facet.

### Claim 18 (depends on 17)

The semiconductor laser device of claim 17, wherein the optical coupler includes an optical waveguide.

### Claim 19 (depends on 18)

The semiconductor laser device of claim 18, wherein the optical waveguide includes single-crystalline silicon or silicon nitride.

### Claim 20 (depends on 15)

The semiconductor laser device of claim 15, wherein a space between the first end of the Fabry Perot cavity and the spacer and a space between the second end of the Fabry Perot cavity and the optical coupler are filled with silicon oxide.