Miscut bulk substrates

• US 9,236,530 B2
• Filed: 03/27/2012
• Issued: 01/12/2016
• Est. Priority Date: 04/01/2011
• Status: Active Grant

• Current Assignee: Korrus Incorporated (MKD Electric, Inc.)
• Original Assignee: Soraa, Inc.
• Inventors: Chakraborty, Arpan, Grundmann, Michael, Tyagi, Anurag
• Primary Examiner(s): Chambliss, Alonzo
• Application Number:
  US13/431,834
• Publication Number:
  US 20130075770A1
• Time in Patent Office: 1,386 Days
• US Class Current: 1/1
• CPC Class Codes: H01L 21/02389 Nitrides
• CPC Class Codes: H01L 21/0243 Surface structure
• 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 33/0075 comprising nitride compounds
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/12 with a stress relaxation structure, e.g. buffer layer
• 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

Abstract

A method for providing (Al,Ga,In)N thin films on Ga-face c-plane (Al,Ga,In)N substrates using c-plane surfaces with a miscut greater than at least 0.35 degrees toward the m-direction. Light emitting devices are formed on the smooth (Al,Ga,In)N thin films. Devices fabricated on the smooth surfaces exhibit improved performance.

Claims

1. A device comprising;

a bulk (Al,Ga,In)N substrate;

a plurality of epitaxial layers overlying the bulk (Al,Ga,In)N substrate and defining a light-emitting device structure,

wherein a top surface of the device structure is characterized by a nominal c-plane crystallographic orientation miscut by an angle from 0.35 degrees to 1 degrees toward an m-direction; and

wherein the epitaxial layers of the light-emitting device structure are configured to have a standard deviation of photoluminescent wavelength uniformity of less than 1% over at least a 2,500 μ

m² area.

2. The device of claim 1, wherein:

the epitaxial layers of the light-emitting device structure are configured such that the top first surface is characterized by a root mean square surface roughness of less than 1 nm over the at least 2,500 μ

m² surface area.

3. The device of claim 2, comprising at least one n-type doped layer overlying the bulk (Al,Ga,In)N substrate.

4. The device of claim 3, comprising at least one active region overlying the at least one n-type doped layer.

5. The device of claim 4, wherein the top surface is characterized by a nominal Ga-face c-plane crystallographic orientation miscut by an angle from 0.35 degrees to 1 degrees toward a <

1-100>

direction, and by an angle from −

1 degree to 1 degree toward a <

11-20>

direction.

6. The device of claim 4, comprising at least one p-type doped layer overlying the at least one active region.

7. The device of claim 4, wherein the at least one active layer comprises AlInGaN.

8. The device of claim 1, wherein the top surface is characterized by an RMS surface roughness from 0.25 nm to 0.6 nm over at least a 2,500 μ

m² surface area.

9. The device of claim 1, wherein the top surface is characterized by a RMS surface roughness less than 0.2 nm over at least a 2,500 μ

m² area.

10. The device of claim 1, wherein the device structure is characterized by a standard deviation of photoluminescent wavelength uniformity is less than 1% over at least a 2,500 μ

m² surface area.

11. The device of claim 1, wherein the device structure is characterized by a standard deviation of photoluminescent wavelength uniformity is less than 0.2% over at least a 2,500 μ

m² surface area.

12. The device of claim 1, wherein the miscut angle is from 0.35 degrees to 0.8 degrees toward the m-direction.

13. The device of claim 1, wherein the top surface is further characterized by a miscut angle from −

1 degrees to 1 degree toward a <

11-20>

direction.

14. The device of claim 1, wherein the device comprises a light emitting diode.

15. The device of claim 14, wherein the light emitting diode is characterized by an output power of at least 2 milliwatts at 20 milliamps drive current.

16. The device of claim 1, wherein the bulk (Al,Ga,In)N is bulk GaN.

17. The device of claim 1, wherein the device comprises a wafer.

18. A semiconductor device fabricated from the wafer of claim 17.