# US 5,706,304 A · Semiconductor laser device

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 5,706,304 A
- Document ID: US5706304A
- Status: Granted
- Kind: A
- Application number: 08/603,237
- Filed: 1996-02-20
- Granted: 1998-01-06
- Earliest claimed: 1995-08-18
- Assignees: Mitsubishi Denki Kabushiki Kaisha
- Inventors: Yuji Ohkura
- Web page: https://patentgrep.com/patent/US5706304A

## CPC

- H01S 5/20: Structure or shape of the semiconductor body to guide the optical wave {; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers}
- H01S 5/2231: {with inner confining structure only between the active layer and the upper electrode}
- H01S 5/2004: {Confining in the direction perpendicular to the layer structure}
- H01S 5/2081: {using special etching techniques}
- H01S 5/209: {special etch stop layers}
- H01S 5/3211: {characterised by special cladding layers, e.g. details on band-discontinuities}
- H01S 5/32316: {comprising only (Al)GaAs}
- 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

A semiconductor laser device includes a first conductivity type GaAs substrate; a first conductivity type first lower cladding layer disposed on the GaAs substrate, lattice-matching with the GaAs substrate, and having an energy band gap; a first conductivity type AlGaAs second lower cladding layer disposed on the first lower cladding layer and having an energy band gap larger than the energy band gap of the first lower cladding layer; an active layer disposed on the second lower cladding layer and having an energy band gap smaller than the energy band gap of the first lower cladding layer; a second conductivity type AlGaAs second upper cladding layer disposed on the active layer and having an energy band gap; a second conductivity type first upper cladding layer disposed on the second upper cladding layer, lattice-matching with the GaAs substrate, and having an energy band gap larger than the energy band gap of the active layer and smaller than the energy band gap of the second upper cladding layer; a second conductivity type GaAs contact layer disposed on the first upper cladding layer; and first and second electrodes respectively disposed on the substrate and the contact layer. In this structure, the stress within the crystalline structure of the laser device is reduced and the crystalline defect density is reduced, whereby the reliability of the device is improved.

## Claims

### Claim 1

A semiconductor laser device comprising:
a first conductivity type GaAs substrate;
a first conductivity type first lower cladding layer disposed on the GaAs substrate, lattice-matching with the GaAs substrate, and having an energy band gap;
a first conductivity type AlGaAs second lower cladding layer disposed on the first lower cladding layer and having an energy band gap larger than the energy band gap of the first lower cladding layer;
an active layer disposed on the second lower cladding layer and having an energy band gap smaller than the energy band gap of the first lower cladding layer;
a second conductivity type AlGaAs second upper cladding layer disposed on the active layer and having an energy band gap;
a second conductivity type first upper cladding layer disposed on the second upper cladding layer, lattice-matching with the GaAs substrate, and having an energy band gap larger than the energy band gap of the active layer and smaller than the energy band gap of the second upper cladding layer;
a second conductivity type GaAs contact layer disposed on the first upper cladding layer; and
first and second electrodes respectively disposed on the substrate and the contact layer.

### Claim 2 (depends on 1)

The semiconductor laser device of claim 1 wherein the first lower cladding layer comprises first conductivity type InGaP, and the first upper cladding layer comprises second conductivity type InGaP.

### Claim 3 (depends on 2)

The semiconductor laser of claim 2 wherein the second upper cladding layer and the second lower cladding layer have thicknesses within a range from 0.1 .mu.m to 0.5 .mu.m.

### Claim 4

A semiconductor laser device comprising:
a first conductivity type semiconductor substrate;
a first conductivity type lower cladding layer disposed on the semiconductor substrate and having an energy band gap;
an active layer disposed on the lower cladding layer and having an energy band gap smaller than the energy band gap of the lower cladding layer;
a second conductivity type first upper cladding layer disposed on the active layer and having an energy band gap larger than the energy band gap of the active layer;
a second conductivity type InGaP first etch stopping layer disposed on the first upper cladding layer and having an energy band gap larger than the energy band gap of the active layer;
a ridge structure comprising a second conductivity type second etch stopping layer disposed on a central portion of the first etch stopping layer and a second conductivity type second upper cladding layer disposed on the second etch stopping layer, the second etch stopping layer comprising a material having an energy band gap larger than the energy band gap of the active layer, resistant to an etchant that etches the second upper cladding layer, and selectively etched by an etchant that does not etch the first etch stopping layer;
first conductivity type current blocking layers disposed on the first etch stopping layer, contacting both sides of the ridge structure; and
first and second electrodes respectively disposed on the substrate and the contact layer.

### Claim 5 (depends on 4)

The semiconductor laser device of claim 4 wherein the second upper cladding layer comprises InGaP, and the second etch stopping layer comprises AlGaAs.

### Claim 6 (depends on 5)

The semiconductor laser device of claim 5 wherein the second etch stopping layer comprises Al.sub.x Ga.sub.1-x As (x-0.3.ltoreq.x.ltoreq.0.5).

### Claim 7 (depends on 4)

The semiconductor laser device of claim 4 wherein the second upper cladding layer comprises AlGaAs, and the second etch stopping layer comprises Al.sub.x Ga.sub.1-x (x.ltoreq.0.6).