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Gallium nitride bulk crystals and their growth method achieved

Foreign code F110003790
File No. E06742US1
Posted date Jul 5, 2011
Country United States of America
Application number 23424408
Gazette No. 20090072352
Gazette No. 8253221
Date of filing Sep 19, 2008
Gazette Date Mar 19, 2009
Gazette Date Aug 28, 2012
Priority data
  • 2007US-60973662 (Sep 19, 2007) US
Title Gallium nitride bulk crystals and their growth method achieved
Abstract (US8253221)
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 mm2 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, and using an autoclave having a high-pressure vessel with an upper region and a lower region.
The temperature of the lower region of the high-pressure vessel is at or above 550° C., the temperature of the upper region of the high-pressure vessel 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.
Scope of claims [claim1]
1. 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 mm2 and a total surface area of the exposed {10-10} m-planes is larger than half of the surface area of the exposed (000-1) N-polar c-plane.
[claim2]
2. The gallium nitride crystal of claim 1, wherein the crystal is grown in supercritical ammonia.
[claim3]
3. The gallium nitride crystal of claim 2, wherein the crystal is grown on a seed crystal and the seed crystal is an a-plane oriented gallium nitride wafer.
[claim4]
4. The gallium nitride crystal of claim 3, wherein the a-plane oriented seed crystal is obtained by slicing a GaN boule grown by an ammonothermal method.
[claim5]
5. The gallium nitride crystal of claim 2, wherein the crystal is grown on a seed crystal and the seed crystal is an m-plane oriented gallium nitride wafer.
[claim6]
6. The gallium nitride crystal of claim 2, wherein the crystal is grown on a seed crystal and the seed crystal is a c-plane oriented gallium nitride wafer.
[claim7]
7. The gallium nitride crystal of claim 2, wherein the crystal is grown on a rod-shaped gallium nitride crystal having its longest dimension along a c-axis.
[claim8]
8. A gallium nitride wafer sliced from the crystal of claim 1.
[claim9]
9. A method for growing gallium nitride (GaN) crystals in a high-pressure vessel, comprising: heating a lower region of an inner room in the high-pressure vessel at or above 550 deg. C., and heating an upper region of the inner room at or above 500 deg. C., while maintaining a temperature difference between the lower region and upper region at or above 30 deg. C.,
wherein the gallium nitride (GaN) crystals have exposed {10-10} m-planes and an exposed (000-1) N-polar c-plane, and a surface area of the exposed (000-1) N-polar c-plane is more than 10 mm2, and a total surface area of the exposed {10--10} m-planes is larger than half of the surface area of the exposed (000-1) N-polar c-plane.
[claim10]
10. The method of claim 9, further comprising: (a) loading alkali-based mineralizers at a bottom of a high-pressure vessel, GaN single crystalline seeds in the lower region of the high-pressure vessel, and Ga-containing materials in the upper region of the high pressure vessel;
(b) filling the high-pressure vessel with ammonia;
(c) sealing the high-pressure vessel;
(d) heating the lower region of the high-pressure vessel with an external heater at or above 550 deg. C., heating the upper region of the high-pressure vessel with external heat at or above 500 deg. C., while maintaining the temperature difference between the lower region and upper region at or above 30 deg. C.;
(e) holding the lower region at or above at or above 550 deg. C., holding the upper region at or above 500 deg. C., and maintaining the temperature difference, for more than 30 days;
(f) releasing high-pressure ammonia at a temperature higher than 300 deg. C.;
(g) unsealing the high-pressure vessel at a temperature higher than 300 deg. C.; and
(h) cooling down the high-pressure vessel; and
(i) wherein the high-pressure vessel is made of a Ni -- Cr based alloy, has a longest dimension along a vertical direction, and has flow-restricting plates to divide an inner room of the high-pressure vessel into the upper region and the lower region.
[claim11]
11. The method of claim 10, wherein the GaN single crystalline seeds have a-plane orientation and are sliced from a GaN crystal grown by an ammonothermal method.
[claim12]
12. A gallium nitride (GaN) crystal having a polyhedron shape with exposed {10--10} m-planes and an exposed (000-1) N-polar c-plane grown by a method comprising: (a) loading alkali-based mineralizers at a bottom of a high-pressure vessel, GaN single crystalline seeds in the lower region of the high-pressure vessel, and Ga-containing materials in the upper region of the high pressure vessel;
(b) filling the high-pressure vessel with ammonia;
(c) sealing the high-pressure vessel;
(d) heating the lower region of the high-pressure vessel with an external heater at or above 550 deg. C., heating the upper region of the high-pressure vessel with external heat at or above 500 deg. C., while maintaining the temperature difference between the lower region and upper region at or above 30 deg. C.;
(e) holding the lower region at or above at or above 550 deg. C., holding the upper region at or above 500 deg. C., and maintaining the temperature difference, for more than 30 days;
(f) releasing high-pressure ammonia at a temperature higher than 300 deg. C.;
(g) unsealing the high-pressure vessel at a temperature higher than 300 deg. C.; and
(h) cooling down the high-pressure vessel; and
(i) wherein the high-pressure vessel is made of a Ni -- Cr based alloy, has a longest dimension along a vertical direction, and has flow-restricting plates to divide an inner room of the high-pressure vessel into the upper region and the lower region,
(j) wherein a surface area of the exposed (000-1) N-polar c-plane is more than 10 mm2, and a total surface area of the exposed {10--10} m-planes is larger than half of the surface area of the exposed (000-1) N-polar c-plane.
[claim13]
13. The GaN crystal of claim 12, wherein the GaN single crystalline seeds have a-plane orientation and are sliced from a GaN crystal grown by an ammonothermal method.
  • Inventor, and Inventor/Applicant
  • HASHIMOTO TADAO
  • NAKAMURA SHUJI
  • JAPAN SCIENCE AND TECHNOLOGY AGENCY
IPC(International Patent Classification)
Reference ( R and D project ) ERATO NAKAMURA Inhomogeneous Crystal AREA
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