Defect reduction in GaN and related materials

• US 20020013042A1
• Filed: 04/16/2001
• Published: 01/31/2002
• Est. Priority Date: 04/17/2000
• Status: Active Grant

• Current Assignee: Virginia Commonwealth University
• Original Assignee: Virginia Commonwealth University
• Inventors: Morkoc, Hadis
• Granted Patent: US 6,657,232 B2
• Time in Patent Office: Days
• US Class Current: 438/604
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: C30B 25/02 Epitaxial-layer growth
• CPC Class Codes: C30B 25/18 characterised by the substrate
• CPC Class Codes: C30B 29/403 AIII-nitrides
• CPC Class Codes: C30B 29/406 Gallium nitride
• CPC Class Codes: H01L 21/0237 Materials
• CPC Class Codes: H01L 21/0242 Crystalline insulating materials
• CPC Class Codes: H01L 21/0245 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/02458 Nitrides
• CPC Class Codes: H01L 21/02507 Alternating layers, e.g. superlattice
• CPC Class Codes: H01L 21/02513 Microstructure
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 33/007 comprising nitride compounds

Abstract

A material with reduced surface defects includes a defect filter layer on an underlying material. The defect filter reduces dislocations and defects present in an underlying material. The defect filter include islands of one material formed on the underlying material and a continuous layer of a second material over the islands. The pair of layers is repeated a plurality of times to reduce the number of defects emanating from the underlying material.

Claims

1. A method for reducing surface defects comprising the steps of:

growing a buffer layer over a substrate; and

growing a defect filter layer on said buffer layer to a thickness sufficient to reduce surface defects wherein said defect filter layer comprises a layer having a plurality of islands.

2. The method of claim 1 wherein said step of growing a buffer layer comprises growing alternating layers of GaN and a buffer layer material having a lattice constant different than GaN.

3. The method of claim 2 wherein said buffer layer material is selected from the group consisting of AlN, InGaN, silicon, AlGaN, and combination thereof.

4. The method of claim 2 wherein said step of growing alternating layers comprises repeating the alternating layers of GaN and said material having a lattice constant different than GaN from about 1 to about 10 times.

5. The method of claim 2 wherein said step of growing said buffer layer begins with growing an initial buffer layer of said material having a lattice constant different than GaN and ends with growing a final buffer layer of said material having a lattice constant different than GaN.

6. The method of claim 1 wherein said step of growing said defect filter layer comprises:

growing alternating layers of said layer having a plurality of GaN islands and a barrier layer having a lattice constant different than GaN.

7. The method of claim 6 wherein said step of growing alternating layers comprises repeating growing alternating layers of said layer having a plurality of GaN islands and a barrier layer having a lattice constant different than GaN from about 1 to about 50 times.

8. The method of claim 6 wherein said step of growing said defect filter layer further comprises initially growing a layer of GaN islands on said buffer layer and ending the defect filter layer with said filter layer material having a different lattice constant than GaN.

9. The method of claim 6 wherein said barrier layer is selected from the group consisting of AlN, InGaN, AlGaN, and combinations thereof.

10. The method of claim 1 wherein said substrate is selected from the group consisting of sapphire, SiC, ZnO, GaAs, and silicon.

11. An article with reduced surface defects comprising:

a substrate;

a buffer layer on one side of said substrate;

a defect filter layer on said buffer layer wherein said defect filter layer has a thickness sufficient to reduce surface defects and wherein said defect filter layer comprises at least one layer having a plurality of GaN islands.

12. The GaN material of claim 11 wherein the defect filter layer further comprises alternating layers of GaN islands and a barrier layer having a lattice constant different than GaN.

13. The GaN material of claim 12 wherein said barrier layer is selected from the group consisting of AlN, InGaN, AlGaN, and combinations thereof.

14. The GaN material of claim 12 wherein the number of alternating layers ranges from about 1 to about 50.

15. The GaN material of claim 12 wherein said defect filter layer has a layer of GaN islands adjacent to said buffer layer.

16. The GaN material of claim 11 wherein said buffer layer comprises alternating layers of GaN and a material having a lattice constant different than GaN.

17. The GaN material of claim 16 wherein said material having a lattice constant different than GaN is a semiconductor.

18. The GaN material of claim 16 wherein said material having a lattice constant different than GaN is selected from the group consisting of AlN, InGaN, silicon, and AlGaN.

19. The GaN material of claim 16 wherein said number of alternating layers ranges from about 1 to about 10

20. The GaN material of claim 16 wherein the initial buffer layer begins with said material having a lattice constant different than GaN and ends with said material having a lattice constant different than GaN.

21. The GaN material of claim 12 wherein said substrate is selected from the group consisting of sapphire, SiC, ZnO, and silicon.

22. A semiconductor nitride layer comprising:

GaN islands formed on a material selected from the group consisting of AlN, InGaN, silicon, and AlGaN and wherein said nitride layer has a surface layer of GaN covering the GaN islands and said material.

23. A material have reduced surface defects comprising:

a base material having a first surface wherein the first surface has surface defects; and

a defect filter layer on said first surface wherein said defect filter layer comprises alternating layers of islands and a barrier layer and wherein said defect filter layer provides a second surface having a reduced number of surface defects relative to said first surface.

24. The material of claim 23 wherein said islands and said barrier layer have different lattice constants.

25. The material of claim 23 wherein said islands are made of an island material selected from the group consisting of GaN, AlN, AlGaN, InGaN, and combinations thereof.

26. The material of claim 23 wherein the island materials and the barrier layer are different from one another and are selected from the group consisting of GaN, AlN, AlGaN, InGaN, and combinations thereof.

27. An article having reduced surface defects comprising:

a material having a surface with defects;

a filter positioned over said substrate wherein said filter layer has at least one layer of islands positioned over said material and at least one barrier layer positioned over said islands; and

a final layer positioned over said filter, the final layer having reduced defects compared to said material.

28. The method of claim 27 wherein said article is selected from the group consisting of an LED, a semiconductor, a laser, a photoelectronic device.

29. A GaN device, comprising:

a GaN substrate;

a second substrate; and

a defect filter layer positioned between said GaN substrate and said second substrate, said defect filter layer having a plurality of alternating continuous barrier layers and discontinuous island layers, said defect filter layer reducing defects on a surface of said GaN substrate.

30. The GaN device of claim 29 further comprising a buffer layer positioned between said GaN substrate and said defect filter layer.

31. The GaN device of claim 29 wherein said discontinuous island layers in said defect filter layer include a plurality of GaN dots.