METHOD FOR IMPROVED GROWTH OF SEMIPOLAR (AL,IN,GA,B)N

• US 20100148195A1
• Filed: 02/22/2010
• Published: 06/17/2010
• Est. Priority Date: 01/20/2006
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Lee, Dong-Seon, Speck, James S., Sato, Hiroshi, Kaeding, John F., Baker, Troy J., DenBaars, Steven P., Haskell, Benjamin A., Nakamura, Shuji, Iza, Michael
• Granted Patent: US 8,110,482 B2
• Time in Patent Office: Days
• US Class Current: 257/94
• 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) a semipolar nitride semiconductor film deposited on a miscut surface of a substrate, wherein a growth 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 direction and magnitude of the miscut are chosen to affect at least one of the following properties of the semipolar nitride semiconductor film:

epitaxial relationship, crystal symmetry, layer polarity, dislocation density, surface morphology and electrical properties.

5. The film of claim 3, wherein the magnitude of the miscut varies depending on the substrate'"'"'s material, an orientation of the semipolar nitride semiconductor film, a type of deposition, and deposition conditions.

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

-20°

.

7. The film of claim 6, wherein the magnitude of the miscut is a miscut angle that preferably varies from 0.5°

-3°

.

9. The method of claim 1, wherein the substrate is miscut in a given crystallographic direction, thereby forming the miscut surface of the substrate and lowering a symmetry of the substrate to match a symmetry of the semipolar nitride semiconductor film.

10. The film of claim 9, wherein the semipolar nitride semiconductor film contains a single crystallographic domain.

11. The film of claim 9, wherein the low symmetry semipolar nitride semiconductor film is deposited heteroepitaxially on the higher symmetry substrate.

12. 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.

13. 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.

14. 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.

15. 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 thin film is homoepitaxially grown on the miscut surface of the substrate.

16. The film of claim 15, wherein the miscut surface comprises a Nitrogen (N) face.

17. 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.

18. The film of claim 17, wherein the preferential nucleation sites provide for improved layer properties, such as better coalescence of nuclei, reduced defect densities or smoother, more planar interfaces or surfaces as compared to deposition on non-miscut surfaces of substrates.

19. The film of claim 1, wherein the semipolar nitride semiconductor film deposited on the miscut surface of the substrate has better crystallinity and reduced threading dislocations as compared to a semipolar nitride semiconductor thin film deposited on non-miscut surfaces of substrates.

20. The film of claim 2, wherein macroscopic surface roughness and faceting of the semipolar nitride semiconductor film decreases with increasing miscut angle.

21. 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 device fabricated on a non-miscut surface of a substrate.

22. The film of claim 21, wherein the miscut surface of the substrate controls a relative orientation of a total polarization field in the device.

23. The film of claim 1, 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.

24. A method of fabricating the film of claim 1.

25. The method of claim 24, further comprising:

(1) miscutting a 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.

26. The method of claim 24, 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.

27. A semiconductor device, comprising:

a lower symmetry layer grown on a higher symmetry substrate, wherein;

(a) the higher symmetry substrate has a miscut surface to match a symmetry of the lower symmetry layer; and

(b) the lower symmetry layer is deposited heteroepitaxially on the miscut surface of the higher symmetry substrate.