Growth of reduced dislocation density non-polar gallium nitride by hydride vapor phase epitaxy

• US 7,220,658 B2
• Filed: 07/15/2003
• Issued: 05/22/2007
• Est. Priority Date: 12/16/2002
• Status: Expired due to Term

• Current Assignee: Japan Science And Technology Agency
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Speck, James S., DenBaars, Steven P., Nakamura, Shuji, Craven, Michael D., Fini, Paul T., Haskell, Benjamin A
• Primary Examiner(s): COLEMAN, WILLIAM D
• Application Number:
  US10/537,644
• Publication Number:
  US 20060128124A1
• Time in Patent Office: 1,407 Days
• Field of Search: 438/481, 257/E21.097
• US Class Current: 438/481
• CPC Class Codes: C30B 25/02 Epitaxial-layer growth
• CPC Class Codes: C30B 29/403 AIII-nitrides
• CPC Class Codes: C30B 29/406 Gallium nitride
• 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 21/02609 Crystal orientation
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 21/02639 Preparation of substrate for selective deposition
• CPC Class Codes: H01L 21/02647 Lateral overgrowth

Abstract

Lateral epitaxial overgrowth (LEO) of non-polar a-plane gallium nitride (GaN) films by hydride vapor phase epitaxy (HVPE) results in significantly reduced defect density.

Claims

1. A method of performing a lateral epitaxial overgrowth of a planar, non-polar, a-plane gallium nitride (GaN) film, comprising:

(a) patterning a mask deposited on a substrate; and

(b) performing a lateral epitaxial overgrowth of the planar, non polar, a-plane GaN film off the substrate using hydride vapor phase epitaxy, wherein the planar, non polar, a-plane GaN film nucleates only on portions of the substrate not covered by the patterned mask, the planar, non polar, a-plane GaN film grows vertically through openings in the patterned mask, and the planar, non polar, a-plane GaN film then spreads laterally above the patterned mask and across the substrate'"'"'s surface.

2. The method of claim 1, wherein the lateral epitaxial overgrowth utilizes growth pressures of approximately atmospheric pressure (760 Torr) or below, and a carrier gas containing a fraction of hydrogen.

3. The method of claim 1, wherein the lateral epitaxial overgrowth reduces threading dislocation densities in the planar, non polar, a-plane GaN film.

4. The method of claim 1, wherein the substrate comprises sapphire.

5. The method of claim 1, wherein the patterned mask is comprised of a metallic material.

6. The method of claim 1, wherein the patterned mask is comprised of a dielectric material.

7. The method of claim 1, wherein the patterned mask is a silicon dioxide (SiO₂) mask containing apertures or stripes allowing access to the substrate underlying the mask.

8. The method of claim 1, wherein the patterning step comprises:

depositing a silicon dioxide (SiO₂) film on the substrate;

patterning a photoresist layer on the silicon dioxide film;

etching away any portions of the silicon dioxide film exposed by the patterned photoresist layer;

removing remaining portions of the photoresist layer; and

cleaning the substrate.

9. The method of claim 1, wherein the substrate is coated with a template layer of GaN, aluminum nitride (AlN), aluminum gallium nitride (AlGaN), or other thin film.

10. The method of claim 1, wherein the substrate is a free-standing a-plane GaN, a-plane aluminum nitride (AlN), or a-plane aluminum gallium nitride (AlGaN) wafer.

11. The method of claim 1, wherein the substrate is coated with a nucleation layer deposited at either low temperatures or at the growth temperature.

12. A free-standing a-plane GaN film or substrate manufactured using the method of claim 1.

13. A device manufactured using the method of claim 1.

14. The method of claim 1, wherein the the planar, non polar, a-plane GaN film then spreads laterally above the patterned mask and across the substrat'"'"'s surface in a manner that creates sharply vertical sidewalls.

15. The method of claim 2, wherein the growth pressure is less than 300 Torr.

16. The method of claim 2, wherein the growth pressure ranges from 5 to 100 Torr.

17. The method of claim 2, wherein the carrier gas is predominantly hydrogen.

18. The method of claim 2, wherein the carrier gas comprises a mixture of hydrogen and nitrogen, argon, or helium.

19. The device of claim 13, wherein the device is a laser diode, light-emitting diode or transistor.

20. A lateral epitaxial overgrowth of a planar, non-polar, a-plane gallium nitride (GaN) film off a substrate, wherein the lateral epitaxial overgrowth is created using a process comprising:

(a) patterning a dielectric mask deposited on a substrate; and

(b) performing a lateral epitaxial overgrowth of the planar, non polar, a-plane GaN film off the substrate using hydride vapor phase epitaxy, wherein the planar, non polar, a-plane GaN film nucleates only on portions of the substrate exposed by the patterned dielectric mask, the planar, non polar, a-plane GaN film grows vertically through openings in the patterned dielectric mask, and the planar, non polar, a-plane GaN film then spreads laterally above the patterned dielectric mask and across the substrate'"'"'s surface.

21. The lateral epitaxial overgrowth of claim 20, wherein the planar, non polar, a-plane GaN film then spreads laterally above the patterned dielectric mask and across the substate'"'"'s surface in a manner that creates sharply vertical sidewalls.