Group III nitride bulk crystals and their fabrication method

Patent metadata

Field	Value
Publication number	US-9790617-B2
Application number	US-201514720819-A
Country	US
Kind code	B2
Filing date	May 24, 2015
Priority date	Apr 7, 2006
Publication date	Oct 17, 2017
Grant date	Oct 17, 2017

Abstract

In one instance, the invention provides a bulk crystal of group III nitride having a thickness of more than 1 mm without cracking above the sides of a seed crystal. This bulk group III nitride crystal is expressed as Ga x1 Al y1 In 1-x1-y1 N (0≦x1≦1, 0≦x1+y1≦1) and the seed crystal is expressed as Ga x2 Al y2 In 1-x2-y2 N (0≦x2≦1, 0≦x2+y2≦1). The bulk crystal of group III nitride can be grown in supercritical ammonia or a melt of group III metal using at least one seed crystal having basal planes of c-orientation and sidewalls of m-orientation. By exposing only c-planes and m-planes in this instance, cracks originating from the sides of the seed crystal are avoided.

First claim

What is claimed is:

1. A bulk crystal of group III nitride having a composition of Ga x1 Al y1 In 1-x1-y1 N (0≦x1≦1, 0≦x1+y1≦1) and containing a seed crystal having a composition of Ga x2 Al y2 In 1-x2-y2 N (0≦x2≦1, 0≦x2+y2≦1), wherein the bulk crystal has a thickness greater than 1 mm and the bulk crystal has fewer cracks within the bulk crystal above the seed crystal's edge than a comparative bulk crystal grown under otherwise identical conditions but grown using a square seed having the same surface area as said seed crystal but having m-plane and a-plane walls.

2. A bulk crystal according to claim 1 wherein said bulk crystal has no cracking above the edges of the seed crystal.

3. A bulk crystal according to claim 1 , wherein the seed crystal has the following characteristics:
(a) a basal plane of the seed is c-plane oriented with miscut angle less than 5 degrees; and
(b) all exposed sidewalls are m-planes with miscut angle less than 5 degrees.

4. A bulk crystal according to claim 3 wherein the seed crystal has a hexagonal shape.

5. A bulk crystal according to claim 4 wherein all of the exposed sides of the seed crystal have a length within +/−10% error of each other.

6. A bulk crystal according to claim 5 wherein the bulk crystal is grown in supercritical ammonia.

7. A bulk crystal according to claim 6 wherein the bulk crystal contains two seed crystals of c-plane orientation having practically identical shape and size with +/−10% error in length, with both Ga-polar face attached on each other so that only N-polar c-planes and m-planes are exposed for growth.

8. A bulk crystal according to claim 3 wherein x2=1.

9. A bulk crystal according to claim 8 wherein x1=1.

10. A bulk crystal of Ga x1 Al y1 In 1-x1-y1 N (0≦x1≦1, 0≦x1+y1≦1) comprising
(a) a seed crystal composed of Ga x2 Al y2 In 1-x2-y2 N (0≦x2≦1, 0≦x2+y2≦1), the seed crystal having a first basal face, a second basal face opposite the first basal face, and a plurality of edge faces extending between the first basal face and the second basal face, said plurality of edge faces extending completely around a perimeter of the first basal face and the second basal face;
(b) a first layer of Ga x1 Al y1 In 1-x1-y1 N (0≦x1≦1, 0≦x1+y1≦1) on the first basal face of said seed crystal
(c) a second layer of Ga x1 Al y1 In 1-x1-y1 N (0≦x1≦1, 0≦x1+y1≦1) on said edge faces of the seed crystal, said second layer having a minimum thickness and a maximum thickness
(d) and wherein the first layer has a thickness of at least five times the maximum thickness of said second layer.

11. A bulk crystal of single-crystal Ga x1 Al y1 In 1-x1-y1 N (0≦x1≦1, 0≦x1+y1≦1) having a seed crystal as a portion of the bulk crystal, wherein the bulk crystal has a thickness greater than 1 mm, and the bulk crystal has no cracks within the bulk crystal above an edge of the seed crystal.

12. A bulk crystal according to claim 11 wherein the bulk crystal is grown in supercritical ammonia.

13. A bulk crystal according to claim 11 wherein the bulk crystal is GaN.

14. A bulk crystal according to claim 11 wherein the seed crystal has a hexagonal shape.

15. A bulk crystal according to claim 11 wherein the edge faces of the seed crystal are prismatic faces of the seed crystal.

16. A bulk crystal according to claim 14 wherein the edge faces of the seed crystal are prismatic faces of the seed crystal.

17. A wafer of group III nitride fabricated from the bulk crystal of claim 1 .

18. A wafer of group III nitride fabricated from the bulk crystal of claim 13 .

19. An electronic, optical, or optoelectronic device formed using a wafer of claim 17 .

20. An electronic, optical, or optoelectronic device formed using a wafer of claim 18 .

Assignees

• Sixpoint Mat Inc
• Seoul Semiconductor Co Ltd

Inventors

• Hashimoto Tadao
• Letts Edward

Classifications

• C30B7/105 Primary

  using ammonia as solvent, i.e. ammonothermal processes · CPC title

• C30B29/66

  Crystals of complex geometrical shape, e.g. tubes, cylinders · CPC title

• C30B29/64

  Flat crystals, e.g. plates, strips or discs · CPC title

• C30B29/403

  AIII-nitrides · CPC title

• C30B9/10

  Metal solvents · CPC title