Gallium nitride bulk crystals and their growth method

Patent metadata

Field	Value
Publication number	US-9243344-B2
Application number	US-201213592750-A
Country	US
Kind code	B2
Filing date	Aug 23, 2012
Priority date	Apr 7, 2006
Publication date	Jan 26, 2016
Grant date	Jan 26, 2016

Abstract

A gallium nitride crystal with a polyhedron shape having exposed {10-10} m-planes and an exposed (000-1) N-polar c-plane, wherein a surface area of the exposed (000-1) N-polar c-plane is more than 10 mm 2 and a total surface area of the exposed {10-10} m-planes is larger than half of the surface area of (000-1) N-polar c-plane. The GaN bulk crystals were grown by an ammonothermal method with a higher temperature and temperature difference than is used conventionally, using a high-pressure vessel with an upper region and a lower region. The temperature of the lower region is at or above 550° C., the temperature of the upper region is set at or above 500° C., and the temperature difference between the lower and upper regions is maintained at or above 30° C. GaN seed crystals having a longest dimension along the c-axis and exposed large area m-planes are used.

First claim

What is claimed is:

1. A method for growing bulk gallium nitride (GaN) crystals, comprising:
growing a gallium nitride crystal having a polyhedron shape with exposed {10-10} m-planes and an exposed (000-1) N-polar c-plane, wherein a surface area of the exposed (000-1) N-polar c-plane is more than 10 mm 2 and a total surface area of all of the exposed {10-10} m-planes is larger than half of the surface area of the exposed (000-1) N-polar c-plane.

2. The method of claim 1 , wherein the exposed (000-1) N-polar c-plane and the exposed {10-10} m-planes are growth surfaces of the crystal.

3. The method of claim 1 , wherein the crystal is grown using an ammonothermal method in supercritical ammonia.

4. The method of claim 3 , wherein the crystal is grown in a high-pressure vessel, and the growing step further comprises heating a first region of the high-pressure vessel at or above 550° C., and heating a second region of the high-pressure vessel at or above 500° C., while maintaining a temperature difference between the first region and second region at or above 30° C.

5. The method of claim 3 , wherein the crystal is grown on a seed crystal and the seed crystal is an a-plane oriented gallium nitride wafer.

6. The method of claim 5 , wherein the a-plane oriented seed crystal is obtained by slicing a GaN boule grown by an ammonothermal method.

7. The method of claim 3 , wherein the crystal is grown on a seed crystal and the seed crystal is an m-plane oriented gallium nitride wafer.

8. The method of claim 3 , wherein the crystal is grown on a seed crystal and the seed crystal is a c-plane oriented gallium nitride wafer.

9. The method of claim 3 , wherein the crystal is grown on a rod-shaped gallium nitride crystal having its longest dimension along a c-axis.

Assignees

• Hashimoto Tadao
• Nakamura Shuji
• Univ California

Inventors

• Hashimoto Tadao
• Nakamura Shuji

Classifications

• C30B29/406 Primary

  Gallium nitride · CPC title

• C30B7/10

  by application of pressure, e.g. hydrothermal processes · CPC title