Method of Selective Photo-Enhanced Wet Oxidation for Nitride Layer Regrowth on Substrates

• US 20120264246A1
• Filed: 04/14/2011
• Published: 10/18/2012
• Est. Priority Date: 04/14/2011
• Status: Active Grant

• Current Assignee: Opto Tech Corporation (OptoTech Corp.)
• Original Assignee: Opto Tech Corporation (OptoTech Corp.)
• Inventors: Peng, Lung-Han, Yu, Jeng-Wei, Yeh, Po-Chun
• Granted Patent: US 8,409,892 B2
• Time in Patent Office: Days
• US Class Current: 438/38
• CPC Class Codes: H01L 21/0242 Crystalline insulating materials
• CPC Class Codes: H01L 21/02458 Nitrides
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/02603 Nanowires
• CPC Class Codes: H01L 21/02639 Preparation of substrate for selective deposition
• CPC Class Codes: H01L 33/007 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 33/32 containing nitrogen

Abstract

Various embodiments of the present disclosure pertain to selective photo-enhanced wet oxidation for nitride layer regrowth on substrates. In one aspect, a method may comprise: forming a first III-nitride layer with a first low bandgap energy on a first surface of a substrate; forming a second III-nitride layer with a first high bandgap energy on the first III-nitride layer; transforming portions of the first III-nitride layer into a plurality of III-oxide stripes by photo-enhanced wet oxidation; forming a plurality of III-nitride nanowires with a second low bandgap energy on the second III-nitride layer between the III-oxide stripes; and selectively transforming at least some of the III-nitride nanowires into III-oxide nanowires by selective photo-enhanced oxidation.

Claims

1. A method comprising:

forming a first III-nitride layer with a first low bandgap energy on a first surface of a substrate;

forming a second III-nitride layer with a first high bandgap energy on the first III-nitride layer;

transforming portions of a surface the second III-nitride layer into a plurality of III-oxide stripes by photo-enhanced wet oxidation;

forming a plurality of III-nitride nanowires with a second low bandgap energy on the second III-nitride layer between the III-oxide stripes; and

selectively transforming at least some of the III-nitride nanowires into III-oxide nanowires by selective photo-enhanced oxidation.

2. The method as recited in claim 1, wherein the selective photo-enhanced wet oxidation comprises photo-enhanced wet oxidation with a photonic energy between the first high bandgap energy and the first low bandgap energy.

3. The method as recited in claim 1, wherein the III-nitride nanowires comprise In/GaN nanowires, and wherein the III-oxide nanowires comprise (In/Ga)₂O₃ nanowires.

4. The method as recited in claim 1, wherein the substrate comprises a C plane (0001) sapphire substrate, wherein the second III-nitride layer comprises a layer of GaN, and wherein the III-oxide stripes are aligned substantially parallel to a [11 2 0] or [1 1 00] direction of GaN.

5. The method as recited in claim 1, further comprising:

forming a third III-nitride layer on the second III-nitride layer and over the III-oxide nanowires; and

removing the III-oxide nanowires to form a plurality of air gaps in the third III-nitride layer.

6. The method as recited in claim 5, wherein forming a third III-nitride layer comprises forming the third III-nitride layer by lateral epitaxy of the III-nitride layer using a metal-organic chemical vapor deposition (MOCVD) process.

7. The method as recited in claim 5, wherein removing the III-oxide nanowires comprises dissolving the III-oxide nanowires using an acidic electrolyte or a basic electrolyte.

8. The method as recited in claim 5, further comprising:

filling the air gaps with a thermally conductive material, the thermally conductive material comprising a plurality of nanoparticles, a plurality of compound particles, or a combination thereof.

9. The method as recited in claim 5, further comprising:

filling the air gaps with an electrically conductive material, the electrically conductive material comprising a plurality of nanoparticles, a plurality of compound particles, or a combination thereof.

10. The method as recited in claim 5, further comprising:

forming a plurality of III-nitride layers on the third III-nitride layer to form at least one light-emitting diode (LED).

11. A method comprising:

forming a first III-nitride layer with a first low bandgap energy on a first surface of a C plane (0001) sapphire substrate;

forming a second III-nitride layer with a first high bandgap energy on the first III-nitride layer;

forming a light-emitting diode (LED) structure over the second III-nitride layer; and

forming, at least in part by selective photo-enhanced oxidation, in the LED structure a plurality of air gaps that are parallel to one another and adjacent the second III-nitride layer.

12. The method as recited in claim 11, wherein forming, at least in part by selective photo-enhanced oxidation, a plurality of air gaps that are parallel to one another and adjacent the second III-nitride layer comprises:

transforming portions of a surface of the second III-nitride layer into a plurality of III-oxide stripes by photo-enhanced wet oxidation;

forming a plurality of III-nitride nanowires with a second low bandgap energy on the second III-nitride layer between the III-oxide stripes;

selectively transforming at least some of the III-nitride nanowires into III-oxide nanowires by selective photo-enhanced oxidation;

forming a third III-nitride layer on the second III-nitride layer and over the III-oxide nanowires; and

removing the III-oxide nanowires to form the plurality of air gaps.

13. The method as recited in claim 11, wherein the selective photo-enhanced wet oxidation comprises photo-enhanced wet oxidation with a photonic energy between the first high bandgap energy and the first low bandgap energy.

14. The method as recited in claim 12, wherein removing the III-oxide nanowires comprises dissolving the III-oxide nanowires using an acidic electrolyte or a basic electrolyte.

15. The method as recited in claim 11, further comprising:

filling the air gaps with a thermally conductive material, the thermally conductive material comprising a plurality of nanoparticles, a plurality of compound particles, or a combination thereof.

16. The method as recited in claim 11, further comprising:

after forming the second III-nitride layer on the first III-nitride layer and before forming the LED structure over the second III-nitride layer, forming a surface passivation layer in a V-notch groove that is in the second III-nitride layer or in a combination of the second III-nitride layer and the first III-nitride layer by selective photo-enhanced oxidation.

17. The method as recited in claim 16, wherein the surface passivation layer comprises a III-oxide layer.

18. The method as recited in claim 16, wherein forming the LED structure over the second III-nitride layer comprises forming a third III-nitride layer on the surface passivation layer and the second III-nitride layer by lateral epitaxy of the III-nitride layer using a metal-organic chemical vapor deposition (MOCVD) process.

19. A method of suppressing screw dislocation in a light-emitting diode (LED) structure, the method comprising:

forming a first III-nitride layer with a first low bandgap energy on a first surface of a substrate;

forming a second III-nitride layer with a first high bandgap energy on the first III-nitride layer;

forming a surface passivation layer of III-oxide in a V-notch groove that is in the second III-nitride layer or in a combination of the second III-nitride layer and the first III-nitride layer by selective photo-enhanced oxidation.

20. The method as recited in claim 19, further comprising:

forming a third III-nitride layer on the surface passivation layer and the second III-nitride layer by selective lateral epitaxy of the third III-nitride layer using a metal-organic chemical vapor deposition (MOCVD) process.