Group III nitride crystals, their fabrication method, and method of fabricating bulk group III nitride crystals in supercritical ammonia

Patent metadata

Field	Value
Publication number	US-9670594-B2
Application number	US-201514957536-A
Country	US
Kind code	B2
Filing date	Dec 2, 2015
Priority date	Apr 7, 2006
Publication date	Jun 6, 2017
Grant date	Jun 6, 2017

Abstract

In one instance, the invention provides a group III nitride crystal having a first side exposing nitrogen polar c-plane of single crystalline or highly oriented polycrystalline group III nitride and a second side exposing group III polar surface, polycrystalline phase, or amorphous phase of group III nitride. Such structure is useful as a seed crystal for ammonothermal growth of bulk group III nitride crystals. The invention also discloses the method of fabricating such crystal. The invention also discloses the method of fabricating a bulk crystal of group III nitride by ammonothermal method using such crystal.

First claim

What is claimed is:

1. A group III nitride crystal comprising:
(a) a first side having an exposed nitrogen polar c-plane surface with miscut angle within +/−5 degree;
(b) a second side opposite to the first side having an exposed group Ill polar c-plane surface, polycrystalline phase or amorphous phase of the group III nitride;
wherein crystal structural quality of the first side is better than crystal structural quality of the second side; and wherein the crystal quality degrades gradually from the first side to the second side of the group III nitride crystal.

2. A group III nitride crystal according to claim 1 , wherein the surface of the first side is free from cracking.

3. A group III nitride crystal according to claim 1 , wherein oxygen concentration of the first side is smaller than oxygen concentration of the second side.

4. A group III nitride crystal according to claim 3 , wherein the oxygen concentration of the second side is more than ten times higher than the oxygen concentration of the first side.

5. A group III nitride crystal according to claim 1 , wherein a full width half maximum (FHWM) of X-ray rocking curve of 002 reflection from the first side is smaller than a full width half maximum of X-ray rocking curve of 002 reflection from the second side.

6. A group III nitride crystal according to claim 5 , wherein the FWHM of the X-ray rocking curve of the 002 reflection from the first side is less than 1000 arcsec.

7. A group III nitride crystal according to claim 6 , wherein the FWHM of the X-ray rocking curve of the 002 reflection from the first side is less than 500 arcsec.

8. A group III nitride crystal according to claim 7 , wherein the FWHM of the X-ray rocking curve of the 002 reflection from the second side is greater than 500 arcsec.

9. A group III nitride crystal according to claim 6 , wherein the FWHM of the X-ray rocking curve of the 002 reflection from the second side is greater than 1000 arcsec.

10. A group III nitride crystal according to claim 1 , wherein the crystal has a thickness of more than 0.1 mm.

11. A group III nitride crystal according to claim 10 , wherein the thickness is more than 0.5 mm.

12. A group III nitride crystal according to claim 10 , wherein the thickness is more than 1 mm.

13. A group III nitride crystal according to claim 1 , wherein the first side is polished sufficiently that the first side is suitable for ammonothermal growth of a bulk crystal.

14. A group III nitride crystal according to claim 1 , wherein the crystal is fabricated by hydride vapor phase epitaxy.

15. A group III nitride crystal according to claim 1 , wherein transition of crystal quality from the first side to the second side is continuous.

16. A group III nitride crystal according to claim 1 , wherein the group III nitride is GaN.

17. A group III nitride crystal according to claim 1 , wherein the crystal has no cracks throughout the crystal.

18. A group III nitride wafer of a crystal of claim 1 .

19. A group III nitride wafer according to claim 18 , wherein the wafer is a single crystal group III nitride wafer.

Assignees

• Sixpoint Mat Inc
• Seoul Semiconductor Co Ltd

Inventors

• Hashimoto Tadao

Classifications

• C30B29/406 Primary

  Gallium nitride · CPC title

• C30B25/02

  Epitaxial-layer growth · CPC title

• C01B21/0632

  with gallium, indium or thallium · CPC title

• C01P2004/60

  Particles characterised by their size · CPC title

• C30B7/105 Primary

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