# US 5,346,856 A · Method of making a selective compositional disordering of a GaAs based heterostructure by the in-diffusion of Au through a single crystal, epitaxially grown Ge film

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- Number: US 5,346,856 A
- Document ID: US5346856A
- Status: Granted
- Kind: A
- Application number: 08/060,073
- Filed: 1993-05-10
- Granted: 1994-09-13
- Earliest claimed: 1993-05-10
- Assignees: The United States of America as represented by the Secretary of the Army
- Inventors: Kenneth A. Jones; Howard S. Lee
- Web page: https://patentgrep.com/patent/US5346856A

## CPC

- H10P 14/3824: {Intermixing, interdiffusion or disordering of III-V heterostructures, e.g. IILD}
- 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 5/2072: {obtained by vacancy induced diffusion}
- H01S 5/341: {Structures having reduced dimensionality, e.g. quantum wires}
- H01S 5/0421: {characterised by the semiconducting contacting layers (electrodes H01S5/0425)}
- H01S 5/04252: {characterised by the material}
- H01S 5/2059: {by means of particular conductivity zones, e.g. obtained by particle bombardment or diffusion}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- 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 method for producing a buried heterostructure active devices and a passive waveguide by providing a heterostructure substrate such as a superlattice having at least one planar GaAs layer and at least one AlGaAs layer adjacent to it. A single crystal germanium layer is epitaxially deposited on the superlattice substrate. A layer of gold is deposited on the germanium layer. The gold and germanium layers are imagewise patterned and selected portions etched away. The patterned substrate is encapsulated in a compatible, heat resistant encapsulating material. The encapsulated substrate is then annealed at a temperature of up to about 350.degree. C.

## Claims

### Claim 1

A method for producing a buried heterostructure device comprising the steps of:
a.) providing a superlattice substrate comprising at least one planar GaAs layer and at least two AlGaAs layers each in juxtaposition with the GaAs layer;
b.) epitaxially depositing a single crystal germanium layer on the superlattice substrate;
c.) depositing a gold layer on the germanium layer;
d.) imagewise patterning and etching away selected portions of the gold and germanium layers;
e.) encapsulating the superlattice substrate in a compatible, heat resistant encapsulating material; and
f.) annealing the encapsulated superlattice substrate to attain homogeneous disordering in an uppermost region of the superlattice substrate.

### Claim 2 (depends on 1)

The method of claim 1 wherein the superlattice substrate comprises a plurality of alternating GaAs and AlGaAs layers in a sandwiched configuration.

### Claim 3 (depends on 1)

The method of claim 1 wherein the superlattice substrate comprises 2 to 100 alternating GaAs and AlGaAs layers in a sandwiched configuration.

### Claim 4 (depends on 1)

The method of claim 1 wherein each GaAs layer has a thickness in the range of about 20 to about 500 Angstroms.

### Claim 5 (depends on 1)

The method of claim 1 wherein each GaAs layer has a thickness in the range of about 20 to about 200 Angstroms.

### Claim 6 (depends on 1)

The method of claim 1 wherein each AlGaAs layer has a thickness in the range of about 10 to about 200 Angstroms.

### Claim 7 (depends on 1)

The method of claim 1 wherein the epitaxial deposition of the germanium layer on the superlattice substrate is conducted at a temperature of from about 350.degree. C. to about 450.degree. C.

### Claim 8 (depends on 1)

The method of claim 1 wherein the depositing the gold layer on the germanium layer is conducted at a temperature of from about 100.degree. C. to about 150.degree. C.

### Claim 9 (depends on 1)

The method of claim 1 wherein the germanium layer has a thickness ranging from about 200 Angstroms to about 500 Angstroms.

### Claim 10 (depends on 1)

The method of claim 1 wherein the gold layer has a thickness ranging from about 100 Angstroms to about 250 Angstroms.

### Claim 11 (depends on 1)

The method of claim 1 wherein the annealing of the encapsulated substrate is conducted at a temperature of from about 300.degree. C. to about 350.degree. C.

### Claim 12 (depends on 1)

The method of claim 1 wherein the annealing of the encapsulated substrate is conducted for from about 2 to about 30 hours.

### Claim 13 (depends on 1)

The method of claim 1 wherein the encapsulating material is silicon nitride.

### Claim 14 (depends on 1)

The method of claim 1 wherein the encapsulating material is silicon dioxide.