Method and System for Epitaxy Processes on Miscut Bulk Substrates

• US 20130075770A1
• Filed: 03/27/2012
• Published: 03/28/2013
• Est. Priority Date: 04/01/2011
• Status: Active Grant

• Current Assignee: Korrus Incorporated (MKD Electric, Inc.)
• Original Assignee: Soraa, Inc.
• Inventors: Grundmann, Michael, Tyagi, Anurag, Chakraborty, Arpan
• Granted Patent: US 9,236,530 B2
• Time in Patent Office: Days
• US Class Current: 257/94
• 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 method for fabricating a device, the method comprising:

providing a gallium and nitrogen containing substrate having a surface region, the surface region being characterized by a c-plane, a miscut angle of at least 0.35 degrees from the c-plane toward the m-direction, and a projection of the surface normal coincides with the m-axis;

forming a gallium and nitrogen containing thin film; and

forming an electrical contact region overlying the thin film.

2. The method of claim 1, wherein the substrate comprises a surface characterized by a miscut angle greater than −

1 degrees, and less than 1 degrees toward the [11-20] direction;

wherein

the device is selected from an optical device and an electrical device; and

the thin film comprises a layer comprises an aluminum bearing species and an indium bearing species.

3. The method of claim 1, wherein the substrate has a miscut away from a low index crystal orientation.

4. The method of claim 1, wherein the thin film material comprises (Al,Ga,In)N.

5. The method of claim 4, wherein:

the (Al,Ga,In)N thin film is grown directly on a Ga-face of the (Al,Ga,In)N substrate which is a miscut c-plane substrate;

wherein the substrate is a Ga-face c-plane substrate and the miscut angle toward the [1-100] direction is at least 0.35 degrees.

6. The method of claim 2, wherein

the thin film is characterized by a surface morphology having a root mean square roughness of less than 0.5 nm over at least a 2,500 μ

m² surface area; and

further comprising causing formation of a resulting substrate characterized by an emission wavelength that is substantially uniform across the surface.

7. The method of claim 1, wherein the substrate is a Ga-face c-plane substrate and the miscut angle is toward the [1-100] direction and is at least 0.35 degrees and less than 1 degree.

8. The method of claim 1, wherein the substrate is a Ga-face c-plane substrate and the miscut angle is toward the [11-20] direction and is greater than −

1 degree and less than 1 degree.

9. The method of claim 1, wherein the substrate is a Ga-face c-plane substrate and the miscut angle is toward the [1-100] direction and is greater than 0.4 degrees and less than 0.8 degrees, and a miscut angle toward the [11-20] direction greater than −

1 degree and less than 1 degree.

10. The method of claim 1, wherein the thin film is a (Al,Ga,In)N film grown directly on a surface of the miscut of the c-plane.

11. The method of claim 10, wherein the thin film is characterized by a surface morphology having a root mean square roughness of less than 0.3 nm over at least a 2,500 μ

m² surface area of the thin film.

12. The method of claim 11, wherein the substrate is a Ga-face c-plane substrate having a miscut angle toward the [1-100] direction at least 0.35 degree, and less than 1 degree, and a miscut angle toward the [11-20] direction greater than −

1 degree and less than 1 degree.

13. The method of claim 1, comprising forming multiple (Al,Ga,In)N layers overlying the surface region in a successive manner.

14. A device comprising (Al,Ga,In)N and a first surface characterized by a c-plane having a miscut angle of at least 0.35 degrees toward the m-direction.

15. The device of claim 14, wherein:

the device is a light emitting diode characterized by a photoluminescent wavelength standard deviation of less than or equal to 0.2%; and

the first surface is characterized by a root mean square surface roughness of less than 1 nm over an area of at least 2,500 μ

m².

16. The device of claim 15, comprising at least one n-type doped layer and at least one p-type doped layer.

17. The device of claim 16, comprising at least one active region.

18. The device of claim 17, wherein the first surface comprises a surface of a Ga-face c-plane substrate having a miscut angle toward the [1-100] direction of at least 0.35 degrees and less than 1 degree;

and a miscut angle toward the [11-20] direction greater than −

1 degree and less than 1 degree.

19. A method for manufacturing an optical device from a bulk gallium and nitrogen containing substrate comprising:

providing the bulk gallium and nitrogen containing substrate having a top surface, wherein at least one surface region on the top surface is a c-plane having a miscut angle of at least 0.35 degrees toward the m-direction;

subjecting the at least one surface region to a treatment process to remove sub-surface damage, the treatment process comprising using a hydrogen and a nitrogen bearing species;

forming a n-type gallium and nitrogen containing material overlying the at least one surface region;

forming an active region comprising multiple thin film layers overlying the n-type gallium and nitrogen containing material, each of the thin film layers comprising an indium species, an aluminum species, and a gallium and nitrogen containing species;

forming an aluminum, gallium, indium, gallium, and nitrogen containing electron blocking material overlying the active region; and

forming a p-type gallium and nitrogen containing material overlying the electron blocking material to cause formation of a processed bulk gallium and nitrogen containing substrate;

wherein the processed bulk gallium and nitrogen containing substrate is characterized by a PL wavelength standard deviation of less than or equal to 0.2%; and

each of the thin film layers comprises a surface region characterized by a root mean square surface roughness of less than or equal to 1 nm over a surface area of at least 2,500 μ

m².

20. The method of claim 19, wherein;

the n-type gallium and nitrogen containing material is n-type GaN;

the p-type gallium and nitrogen containing material is p-type GaN;

the electron blocking material is AlGaN;

each of the layers in the active region is AlInGaN; and

the active region comprises a plurality of quantum wells, wherein the plurality of quantum wells comprise from three to twenty quantum wells, each of the quantum wells being separated by a barrier region, each of the barrier regions comprising GaN.