Method and surface morphology of non-polar gallium nitride containing substrates

• US 8,575,728 B1
• Filed: 07/13/2012
• Issued: 11/05/2013
• Est. Priority Date: 05/29/2009
• Status: Active Grant

• Current Assignee: SL Technology Incorporated (Reliv' International, Inc.)
• Original Assignee: Soraa, Inc.
• Inventors: Raring, James W., Poblenz, Christiane
• Primary Examiner(s): HA, NATHAN W
• Application Number:
  US13/548,635
• Time in Patent Office: 480 Days
• Field of Search: 257627-628, 257/94, 372/44.011, 117101-104
• US Class Current: 257/628
• CPC Class Codes: H01L 33/16 with a particular crystal structure or orientation, e.g. polycrystalline, amorphous or porous
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01S 2304/04 MOCVD or MOVPE
• CPC Class Codes: H01S 5/32025 non-polar orientation
• CPC Class Codes: H01S 5/32341 blue laser based on GaN or GaP

Abstract

An optical device, e.g., LED, laser. The device includes a non-polar gallium nitride substrate member having a slightly off-axis non-polar oriented crystalline surface plane. In a specific embodiment, the slightly off-axis non-polar oriented crystalline surface plane is up to about −0.6 degrees in a c-plane direction, but can be others. In a specific embodiment, the present invention provides a gallium nitride containing epitaxial layer formed overlying the slightly off-axis non-polar oriented crystalline surface plane. In a specific embodiment, the device includes a surface region overlying the gallium nitride epitaxial layer that is substantially free of hillocks.

Claims

1. An optical device comprising:

a gallium- and nitrogen-containing substrate having an off-axis non-polar oriented crystalline surface plane, the off-axis non-polar oriented crystalline surface plane being defined from the non-polar (10-10) plane with a negative angle toward the c-plane (0001), a magnitude of the negative angle being greater than about 0.6 degrees;

a gallium- and nitrogen-containing epitaxial layer overlying the off-axis non-polar oriented crystalline surface plane; and

a surface region overlying the gallium- and nitrogen-containing epitaxial layer, the surface region being substantially free from hillocks.

2. The device of claim 1 wherein the magnitude of the negative angle is greater than about 0.7 degrees.

3. The device of claim 1 wherein the magnitude of the negative angle is greater than about 0.8 degrees.

4. The device of claim 1 wherein the magnitude of the negative angle is greater than about 0.9 degrees.

5. The device of claim 1 wherein the magnitude of the negative angle is greater than about 1.0 degrees.

6. The device of claim 1 wherein the magnitude of the negative angle is greater than about 1.1 degrees.

7. The device of claim 1 wherein the magnitude of the negative angle is greater than about 1.2 degrees;

and wherein the optical device is a laser diode.

8. The device of claim 1 further comprising an optical device overlying the gallium nitride containing epitaxial layer.

9. The device of claim 1 wherein the gallium- and nitrogen-containing epitaxial layer comprises the surface region that is substantially free from hillocks.

10. The device of claim 1 wherein the gallium- and nitrogen-containing epitaxial layer comprises the surface region, and at least 90% of the surface region is free from hillocks.

11. The device of claim 1 wherein the gallium- and nitrogen-containing epitaxial layer comprises the surface region, the surface region being substantially free from hillocks with lengths ranging from about 10 microns to about 100 microns.

12. The device of claim 1 wherein the gallium- and nitrogen-containing epitaxial layer comprises the surface region, the surface region being substantially free from hillocks with lengths ranging from 100 microns to about 200 microns.

13. The device of claim 1 wherein the surface region is substantially free from hillocks with a substantially rectangular footprint that is elongated in an a-plane direction.

14. The device of claim 1 wherein the surface region is substantially free from hillocks with a pyramidal-like shape.

15. An optical device comprising:

a gallium- and nitrogen-containing substrate having an off-axis non-polar oriented crystalline surface plane, the off-axis non-polar oriented crystalline surface plane being defined from the non-polar (10-10) plane with an angle ranging from about 0 degrees to a predetermined angle toward either or both the c-plane and the a-plane;

a gallium- and nitrogen-containing epitaxial layer overlying the off-axis non-polar oriented crystalline surface plane, the gallium- and nitrogen-containing epitaxial layer comprising at least a region of a quantum well formed by at least an atmospheric pressure epitaxial formation process, the quantum well being at least 3.5 nanometers thick; and

a surface region overlying the gallium- and nitrogen-containing epitaxial layer, the surface region being substantially free from hillocks.

16. The device of claim 15 wherein the gallium- and nitrogen-containing epitaxial layer comprises multiple quantum wells or multiple layers including n-type and p-type regions.

17. The device of claim 15 wherein the atmospheric pressure ranges from about 700 Torr to about 800 Torr;

and wherein the optical device is a laser diode.

18. The device of claim 15 wherein the surface region is substantially free from hillocks with a substantially rectangular footprint that is elongated in an a-plane direction.

19. The device of claim 15 wherein the surface region is substantially free from hillocks with a pyramidal-like shape.

20. The device of claim 15 wherein the off-axis non-polar oriented crystalline surface plane has an on-axis orientation.

21. The device of claim 15 wherein the gallium- and nitrogen-containing epitaxial layer comprises the surface region that is substantially free from hillocks.

22. The device of claim 15 wherein the gallium- and nitrogen-containing epitaxial layer comprises the surface region that is substantially free from hillocks with lengths ranging from about 10 microns to about 100 microns.

23. The device of claim 15 wherein the gallium- and nitrogen-containing epitaxial layer comprises the surface region that is substantially free from hillocks with lengths ranging from about 100 microns to about 200 microns.

24. The device of claim 15 wherein the gallium- and nitrogen-containing epitaxial layer comprises the surface region, and at least 90% of the surface region is free from hillocks.