Vicinal gallium nitride substrate for high quality homoepitaxy
View Patent ↗A III-V nitride, e.g., GaN, substrate including a (0001) surface offcut from the <0001> direction predominantly toward a direction selected from the group consisting of <10-10> and <11-20> directions, at an offcut angle in a range that is from about 0.2 to about 10 degrees, wherein the surface has a RMS roughness measured by 50×50 μm 2 AFM scan that is less than 1 nm, and a dislocation density that is less than 3E6 cm −2 . The substrate may be formed by offcut slicing of a corresponding boule or wafer blank, by offcut lapping or growth of the substrate body on a corresponding vicinal heteroepitaxial substrate, e.g., of offcut sapphire. The substrate is usefully employed for homoepitaxial deposition in the fabrication of III-V nitride-based microelectronic and opto-electronic devices.
1. An (Al,In,Ga)N substrate including a (Al,In,Ga)N (0001) surface offcut from the [0001] direction at a non-zero angle, and a (Al,In,Ga)N (000 1 ) surface offcut from the [000 1 ] direction at a non-zero angle.
2. The (Al,In,Ga)N substrate of claim 1 , wherein the (Al,In,Ga)N (0001) surface is offcut from the [0001] direction predominantly towards a direction selected from the group consisting of <10 1 0> and <11 2 0> directions.
3. The (Al,In,Ga)N substrate of claim 1 , wherein the (Al,In,Ga)N (0001) surface is offcut predominantly toward the <10 1 0> direction.
4. The (Al,In,Ga)N substrate of claim 1 , wherein the (Al,In,Ga)N (0001) surface is offcut predominantly toward the <11 2 0> direction.
5. The (Al,In,Ga)N substrate of claim 1 , wherein the offcut (Al,In,Ga)N (0001) surface is offcut from the [0001] direction at an offcut angle in a range from about 0.2 to about 10 degrees, and wherein the (Al,In,Ga)N (000 1 ) surface is offcut from the [0001] direction at an offcut angle in a range from about 0.2 to about 10 degrees.
6. The (Al,In,Ga)N substrate of claim 1 , wherein each of the offcut (Al,In,Ga)N (0001) surface and the offcut (Al,In,Ga)N (000 1 ) surface has the same magnitude offcut.
7. The (Al,In,Ga)N substrate of claim 1 , wherein the offcut (Al,In,Ga)N (0001) surface is parallel to the offcut (Al,In,Ga)N (000 1 ) surface.
8. The (Al,In,Ga)N substrate of claim 1 , wherein the offcut (Al,In,Ga)N (0001) surface has a RMS roughness measured by 50×50 μm 2 AFM scan that is less than 0.9 nm.
9. The (Al,In,Ga)N substrate of claim 1 , wherein the offcut (Al,In,Ga)N (0001) surface has a dislocation density that is less than 1E6 cm −2 .
10. The (Al,In,Ga)N substrate of claim 1 , wherein the offcut (Al,In,Ga)N (0001) surface has a dislocation density that is less than 5E5 cm −2 .
11. The (Al,In,Ga)N substrate of claim 1 , wherein the offcut (Al,In,Ga)N (0001) surface has a RMS roughness measured by 50×50 μm 2 AFM scan that is less than 1 nm, and a dislocation density that is less than 3E6 cm −2 .
12. The (Al,In,Ga)N substrate of claim 1 , wherein the (Al,In,Ga)N (0001) surface is offcut from the [0001] direction predominantly towards a direction selected from the group consisting of <10 1 0> and <11 1 0> directions, at an offcut angle of from about 2.5 to about 10 degrees, wherein said offcut (Al,In,Ga)N (0001) surface has a RMS roughness measured by 50×50 μm 2 AFM scan that is less than 1 nm, and a dislocation density that is less than 3E6 cm −2 .
13. A microelectronic or opto-electronic device article, comprising the (Al,In,Ga)N substrate of claim 1 , and a microelectronic or opto-electronic device structure including a homoepitaxial (Al,In,Ga)N layer deposited on said surface.
14. An (Al,In,Ga)N substrate including a (Al,In,Ga)N (0001) surface offcut from the [0001] direction at an angle in a range from about 0.2 to about 10 degrees, and including a (Al,In,Ga)N (000 1 ) surface offcut from the [000 1 ] direction at an angle in a range from about 0.2 to about 10 degrees, wherein the (Al,In,Ga)N (0001) surface is offcut from the <0001> direction predominantly towards a direction selected from the group consisting of <10 1 0> and <11 1 0> directions.
15. The (Al,In,Ga)N substrate of claim 14 , wherein said offcut (Al,In,Ga)N (0001) surface has a RMS roughness measured by 50×50 μm 2 AFM scan that is less than 1 nm, and a dislocation density that is less than 3E6 cm −2 .
16. The (Al,In,Ga)N substrate of claim 14 , wherein the offcut (Al,In,Ga)N (0001) surface is parallel to the offcut (Al,In,Ga)N (000 1 ) surface.
17. The (Al,In,Ga)N substrate of claim 14 , wherein the offcut (Al,In,Ga)N (0001) surface has the same magnitude offcut as the offcut (Al,In,Ga)N (000 1 ) surface.
18. A microelectronic or opto-electronic device article, comprising the (Al,In,Ga)N substrate of claim 14 , and a microelectronic or opto-electronic device structure including a homoepitaxial (Al,In,Ga)N layer deposited on said surface.
19. A method of making an (Al,In,Ga)N substrate according to claim 1 comprising:
surface processing a (Al,In,Ga)N wafer along a first side thereof produce a (Al,In,Ga)N wafer having a wedge conformation; and
surface processing the (Al,In,Ga)N wafer having a wedge conformation along a second side thereof to alter the wedge conformation;
wherein, following the first and second surface processing steps, the first side of the (Al,In,Ga)N wafer is tilted away from the (Al,In,Ga)N lattice c-plane, and the second side of the (Al,In,Ga)N wafer is tilted away from the (Al,In,Ga)N lattice c-plane.
20. The method of claim 19 , wherein following the first and second lapping steps, any of the following conditions are satisfied:
the first side of the (Al,In,Ga)N wafer is parallel to the second side of the (Al,In,Ga)N wafer; and
each of the offcut (Al,In,Ga)N (0001) surface and the offcut (Al,In,Ga)N (000 1 ) surface has the same magnitude offcut.