Abbreviated epitaxial growth mode (AGM) method for reducing cost and improving quality of LEDs and lasers

• US 8,541,252 B2
• Filed: 12/17/2010
• Issued: 09/24/2013
• Est. Priority Date: 12/17/2009
• Status: Active Grant

• Current Assignee: Lehigh University
• Original Assignee: Lehigh University
• Inventors: Tansu, Nelson, Chan, Helen M., Vinci, Richard P., Ee, Yik-Khoon, Biser, Jeffrey
• Primary Examiner(s): Mandala, Victor A
• Assistant Examiner(s): MOORE, WHITNEY
• Application Number:
  US12/972,418
• Publication Number:
  US 20110147703A1
• Time in Patent Office: 1,012 Days
• Field of Search: 257/13, 257/14, 257/98, 257/200, 257/E33.008, 257/E33.067, 257/E21.09, 438/29, 438/46, 438/47, 438/478
• US Class Current: 438/46
• CPC Class Codes: C30B 25/183 being provided with a buffer layer, e.g. a lattice matching layer
• CPC Class Codes: C30B 29/406 Gallium nitride
• CPC Class Codes: H01L 21/0242 Crystalline insulating materials
• CPC Class Codes: H01L 21/0243 Surface structure
• CPC Class Codes: H01L 21/02458 Nitrides
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/02658 Pretreatments cleaning in general H01L21/02041
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate

Abstract

The use of an abbreviated GaN growth mode on nano-patterned AGOG sapphire substrates, which utilizes a process of using 15 nm low temperature GaN buffer and bypassing etch-back and recovery processes during epitaxy, enables the growth of high-quality GaN template on nano-patterned AGOG sapphire. The GaN template grown on nano-patterned AGOG sapphire by employing abbreviated growth mode has two orders of magnitude lower threading dislocation density than that of conventional GaN template grown on planar sapphire. The use of abbreviated growth mode also leads to significant reduction in cost of the epitaxy. The growths and characteristics of InGaN quantum wells (QWs) light emitting diodes (LEDs) on both templates were compared. The InGaN QWs LEDs grown on the nano-patterned AGOG sapphire demonstrated at least a 24% enhancement of output power enhancement over that of LEDs grown on conventional GaN templates.

Claims

1. A method of growing a GaN template on a substrate, comprising:

performing an abbreviated GaN growth mode (AGGM) on a patterned sapphire substrate, said AGGM including;

growing a thin low-temperature GaN layer on said substrate; and

growing a thick high-temperature GaN layer on said thin layer.

2. The method of claim 1, wherein said growing of said thick high-temperature GaN layer is performed immediately following the growing of said thin low-temperature GaN layer.

3. The method of claim 2, wherein said thin low-temperature GaN layer has a thickness in the range of about 10-20 nm.

4. The method of claim 3, wherein said thick high-temperature GaN layer has a thickness in the range of about 0.10-0.30 μ

m.

5. The method of claim 3, wherein said thick high-temperature GaN layer has a thickness of about 0.25 μ

m.

6. The method of claim 5, wherein said low-temperature GaN layer is grown at a temperature in the range of about 525-545°

C.

7. The method of claim 6, wherein said high-temperature GaN layer is grown at a temperature in the range of about 1070-1090°

C.

8. The method of claim 6, wherein said high-temperature GaN layer is grown at a temperature of about 1080°

C.

9. The method of claim 6, wherein said patterned sapphire comprises nano-patterned sapphire etched using an AGOG process.

10. The method of claim 5, wherein said low-temperature GaN layer is grown at a temperature of about 535°

C.

11. The method of claim 2, wherein said thin low-temperature GaN layer has a thickness of about 15 nm.

12. The method of claim 1, wherein said patterned sapphire comprises nano-patterned sapphire.

13. An LED formed using the following steps:

growing a GaN template on a substrate, comprising;

performing an abbreviated GaN growth mode (AGGM) on a patterned sapphire substrate, said AGGM including;

growing a thin low-temperature GaN layer on said substrate; and

growing a thick high-temperature GaN layer on said thin layer; and

growing an InGaN QWs LED on said GaN template.

14. The method of claim 13, wherein said patterned sapphire comprises nano-patterned sapphire.