Method for significant reduction of dislocations for a very high A1 composition A1GaN layer

• US 20060264009A1
• Filed: 04/25/2006
• Published: 11/23/2006
• Est. Priority Date: 04/25/2005
• Status: Active Grant

• Current Assignee: Epistar Corporation (Ennostar, Inc.)
• Original Assignee: CAO Group, Inc.
• Inventors: Wang, Tao
• Granted Patent: US 7,776,636 B2
• Time in Patent Office: Days
• US Class Current: 438/479
• CPC Class Codes: C30B 25/02 Epitaxial-layer growth
• CPC Class Codes: C30B 25/183 being provided with a buffer layer, e.g. a lattice matching layer
• CPC Class Codes: C30B 29/403 AIII-nitrides
• CPC Class Codes: H01L 21/0242 Crystalline insulating materials
• CPC Class Codes: H01L 21/02458 Nitrides
• CPC Class Codes: H01L 21/02513 Microstructure
• CPC Class Codes: H01L 21/0254 Nitrides

Abstract

A method for reducing dislocation density between an AlGaN layer and a sapphire substrate involving the step of forming a self-organizing porous AlN layer of non-coalescing column-like islands with flat tops on the substrate.

Claims

1. A method for reduction of dislocation density in an AlGaN semiconductor comprising the steps of:

preparing a sapphire substrate for epitaxial layer growth,

introducing a self-organized porous AlN layer on said subtrate, and

growing an AlGaN layer on said AlN layer.

2. A method as recited in claim 1 wherein ex-situ pattering processes on said substrate are not implemented.

3. A method as recited in claim 1 wherein said AlGaN layer is Al_0.98Ga_0.02N.

4. A method as recited in claim 1 wherein said AlN layer is formed at least in part by use of transmission electron microscopy.

5. A method as recited in claim 1 wherein said AlN layer is formed at least in part by use of atomic force microscopy.

6. A method as recited in claim 1 wherein said AlN layer is formed at least in part by use of x-ray diffraction.

7. A method as recited in claim 1 wherein said AlN layer is formed by use of a combination of atomic force microscopy, x-ray diffraction and transmission electron microscopy in order to achieve an AlN layer that lacks both overgrowth and an ex-situ pattering process.

8. A method as recited in claim 7 wherein said AlN layer exhibits non-coalescing column-like islands with flat tops.