Miscut semipolar optoelectronic device

• US 8,110,482 B2
• Filed: 02/22/2010
• Issued: 02/07/2012
• Est. Priority Date: 01/20/2006
• Status: Active Grant

• Current Assignee: Japan Science And Technology Agency, Regents of the University of California (University of California)
• Original Assignee: Japan Science And Technology Agency, Regents of the University of California (University of California)
• Inventors: Kaeding, John F., Lee, Dong-Seon, Iza, Michael, Baker, Troy J., Sato, Hitoshi, Haskell, Benjamin A., Speck, James S., DenBaars, Steven P., Nakamura, Shuji
• Primary Examiner(s): Ghyka, Alexander
• Assistant Examiner(s): Chang, Leonard
• Application Number:
  US12/710,181
• Publication Number:
  US 20100148195A1
• Time in Patent Office: 715 Days
• Field of Search: 257/200, 257/201, 257/628, 257/E21.113, 438/478, 438/479, 438/604, 438/775
• US Class Current: 438/478
• CPC Class Codes: C30B 23/025 characterised by the substrate
• CPC Class Codes: C30B 25/02 Epitaxial-layer growth
• CPC Class Codes: C30B 25/18 characterised by the substrate
• CPC Class Codes: C30B 25/183 being provided with a buffer layer, e.g. a lattice matching layer
• CPC Class Codes: C30B 29/403 AIII-nitrides
• CPC Class Codes: C30B 29/406 Gallium nitride
• CPC Class Codes: H01L 21/02378 Silicon carbide
• CPC Class Codes: H01L 21/0242 Crystalline insulating materials
• CPC Class Codes: H01L 21/02433 Crystal orientation
• CPC Class Codes: H01L 21/02458 Nitrides
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 33/007 comprising nitride compounds

Abstract

A method for improved growth of a semipolar (Al,In,Ga,B)N semiconductor thin film using an intentionally miscut substrate. Specifically, the method comprises intentionally miscutting a substrate, loading a substrate into a reactor, heating the substrate under a flow of nitrogen and/or hydrogen and/or ammonia, depositing an In_xGa_1-xN nucleation layer on the heated substrate, depositing a semipolar nitride semiconductor thin film on the In_xGa_1-xN nucleation layer, and cooling the substrate under a nitrogen overpressure.

Claims

1. A semiconductor film, comprising:

a semipolar nitride semiconductor film deposited on a miscut surface of a substrate, wherein a top surface of the semipolar nitride semiconductor film is more than 10 microns wide and is substantially parallel to the miscut surface of the substrate.

2. The film of claim 1, wherein the miscut surface of the substrate is miscut away from a low index crystal orientation.

3. The film of claim 2, wherein the miscut has a magnitude and direction.

4. The film of claim 3, wherein the magnitude of the miscut is a miscut angle that ranges from 0.5°

-20°

.

5. The film of claim 4, wherein the magnitude of the miscut is a miscut angle that varies from 0.5°

-3°

.

6. The film of claim 1, wherein the substrate is miscut in a given crystallographic direction, thereby forming the miscut surface of the substrate that lowers a symmetry of the substrate to match a symmetry of the semipolar nitride semiconductor film.

7. The film of claim 6, wherein the semipolar nitride semiconductor film contains a single crystallographic domain.

8. The film of claim 1, wherein the semipolar nitride semiconductor film is deposited heteroepitaxially on the substrate and the semipolar nitride semiconductor film has lower symmetry than a symmetry of the substrate.

9. The film of claim 1, wherein the semipolar nitride semiconductor film comprises an alloy composition of (Ga,Al,In,B)N semiconductors having a formula of Ga_nAl_xIn_yB_zN where 0≦

n≦

1, 0≦

x≦

1, 0≦

y ≦

1, 0≦

z≦

1 and n+x+y+z=1.

10. The film of claim 1, wherein the semipolar nitride semiconductor film is a {10-11} nitride and the substrate is a {100} MgAl₂O₄ spinel substrate miscut in the <

011>

direction.

11. The film of claim 1, wherein the semipolar nitride semiconductor film is a {11-22} nitride and the substrate is a {1-100} Al₂O₃ sapphire substrate miscut in the <

0001>

direction.

12. The film of claim 1, wherein the substrate is a bulk nitride crystal having the miscut surface along a semipolar plane and the semipolar nitride semiconductor film is homoepitaxially grown on the miscut surface of the substrate.

13. The film of claim 12, wherein the miscut surface comprises a Nitrogen (N) face.

14. The film of claim 1, wherein the miscut surface of the substrate provides step edges or kinks that serve as preferential nucleation sites for growth of the semipolar nitride semiconductor film.

15. The film of claim 14, wherein miscut surface provides reduced defect densities or smoother, more planar interfaces or surfaces of the semipolar nitride semiconductor film, as compared to deposition of a similar semipolar nitride semiconductor film on non-miscut surfaces of substrates under similar deposition conditions.

16. The film of claim 1, wherein the miscut surface is such that the semipolar nitride semiconductor film deposited on the miscut surface of the substrate has better crystallinity and reduced threading dislocations as compared to a similar semipolar nitride semiconductor film deposited on non-miscut surfaces of substrates under similar deposition conditions.

17. The film of claim 1, wherein the film is part of a device, and the device is a light emitting device having a brighter emission than a similar device fabricated on a non-miscut surface of a substrate.

18. The film of claim 1, wherein the semipolar nitride semiconductor film deposited heteroepitaxially on the miscut surface of the substrate and the substrate is a different material from gallium nitride.

19. A method of fabricating a semiconductor film, comprising:

depositing a semipolar nitride semiconductor film on a miscut surface of a substrate, wherein a top surface of the semipolar nitride semiconductor film is more than 10 microns wide and is substantially parallel to the miscut surface of the substrate.

20. The method of claim 19, further comprising:

(1) miscutting the substrate;

(2) loading the substrate into a reactor;

(3) heating the substrate under a flow comprising at least one of nitrogen, hydrogen or ammonia;

(4) depositing the semipolar nitride semiconductor film on the heated substrate; and

(5) cooling the substrate under a nitrogen overpressure.

21. The method of claim 20, wherein the depositing step (4) comprises:

(i) depositing a nucleation layer on the heated substrate; and

(ii) depositing the semipolar nitride semiconductor film on the nucleation layer.

22. The method of claim 19, wherein the miscut surface of the substrate is miscut away from a low index crystal orientation.

23. The method of claim 22, wherein the miscut has a magnitude and a direction, and the magnitude of the miscut is a miscut angle that ranges from 0.5°

-20°

.

24. The method of claim 23, wherein the magnitude of the miscut is a miscut angle that varies from 0.5°

-3°

.

25. The method of claim 19, wherein the substrate is miscut in a given crystallographic direction, thereby forming the miscut surface of the substrate that lowers a symmetry of the substrate to match a symmetry of the semipolar nitride semiconductor film.

26. The method of claim 25, wherein the semipolar nitride semiconductor film contains a single crystallographic domain.

27. The method of claim 19, wherein the semipolar nitride semiconductor film is deposited heteroepitaxially on the substrate and the semipolar nitride semiconductor film has lower symmetry than a symmetry of the substrate.

28. The method of claim 19, wherein the semipolar nitride semiconductor film comprises an alloy composition of (Ga,Al,In,B)N semiconductors having a formula of Ga_nAl_xIn_yB_zN where 0≦

n≦

1, 0≦

x≦

1, 0≦

y≦

1, 0≦

z≦

1 and n+x+y+z=1.

29. The method of claim 19, wherein the semipolar nitride semiconductor film is a {10-11} nitride and the substrate is a {100} MgAl₂O₄ spinel substrate miscut in the <

011>

direction.

30. The method of claim 19, wherein the semipolar nitride semiconductor film is a {11-22} nitride and the substrate is a {1-100} Al₂O₃ sapphire substrate miscut in the <

0001>

direction.

31. The method of claim 19, wherein the substrate is a bulk nitride crystal having the miscut surface along a semipolar plane and the semipolar nitride semiconductor film is homoepitaxially grown on the miscut surface of the substrate.

32. The method of claim 31, wherein the miscut surface comprises a Nitrogen (N) face.

33. The method of claim 19, wherein the miscut surface of the substrate provides step edges or kinks that serve as preferential nucleation sites for growth of the semipolar nitride semiconductor film.

34. The method of claim 33, further comprising selecting the miscut surface that provides reduced defect densities or smoother, more planar interfaces or surfaces of the semipolar nitride semiconductor film, as compared to deposition of a similar semipolar nitride semiconductor film on non-miscut surfaces of substrates under similar deposition conditions.

35. The method of claim 19, further comprising selecting the miscut surface such that the semipolar nitride semiconductor film deposited on the miscut surface of the substrate has better crystallinity and reduced threading dislocations as compared to a similar semipolar nitride semiconductor film deposited on non-miscut surfaces of substrates under similar deposition conditions.

36. The method of claim 19, wherein the semiconductor nitride film is part of a device, and the device is a light emitting device having a brighter emission than a similar device fabricated on a non-miscut surface of a substrate.

37. The method of claim 36, further comprising controlling a relative orientation of a total polarization field in the device by controlling a miscut angle of the miscut surface of the substrate.

38. The method of claim 19, wherein the semipolar nitride semiconductor film is deposited heteroepitaxially on the miscut surface of the substrate and the substrate is a different material from gallium nitride.