Group III-nitride layers with patterned surfaces

• US 8,070,966 B2
• Filed: 12/01/2008
• Issued: 12/06/2011
• Est. Priority Date: 03/26/2003
• Status: Active Grant

• Current Assignee: Alcatel-Lucent SA (Nokia Corporation)
• Original Assignee: Alcatel-Lucent SA (Nokia Corporation)
• Inventors: Chowdhury, Aref, Ng, Hock, Slusher, Richart Elliott
• Primary Examiner(s): Norton, Nadine G
• Assistant Examiner(s): Lin, Patti
• Application Number:
  US12/315,202
• Publication Number:
  US 20090139957A1
• Time in Patent Office: 1,100 Days
• Field of Search: 216/11, 216/13, 216/83, 216/95, 216/96, 438/46, 438/47, 438/22, 438/93, 438/94, 438/172, 438/602, 438/604, 438/606, 438/745, 313/309, 313/310, 313/311, 257/98, 257/99, 445 23- 45, 445/49, 117/22, 117/26, 117/43, 117/63, 117/75
• US Class Current: 216/11
• CPC Class Codes: B81B 1/00 Devices without movable or flexible elements, e.g. microcapillary devices
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02B 2006/12035 Materials
• CPC Class Codes: G02B 6/1225 comprising photonic band-gap structures or photonic lattices
• CPC Class Codes: H01J 1/304 Field-emissive cathodes
• CPC Class Codes: H01J 3/022 with microengineered cathode, e.g. Spindt-type
• CPC Class Codes: H01J 9/025 of field emission cathodes
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/02639 Preparation of substrate for selective deposition
• CPC Class Codes: H01L 21/30612 Etching of AIIIBV compounds

Abstract

A fabrication method produces a mechanically patterned layer of group III-nitride. The method includes providing a crystalline substrate and forming a first layer of a first group III-nitride on a planar surface of the substrate. The first layer has a single polarity and also has a pattern of holes or trenches that expose a portion of the substrate. The method includes then, epitaxially growing a second layer of a second group III-nitride over the first layer and the exposed portion of substrate. The first and second group III-nitrides have different alloy compositions. The method also includes subjecting the second layer to an aqueous solution of base to mechanically pattern the second layer.

Claims

1. A method of fabricating a structure, comprising:

providing a substrate with a planar surface;

forming a crystalline layer of a group III-nitride over the surface of the substrate; and

subjecting the layer to an aqueous solution of base to etch a top surface of the layer such that a plurality of pyramids are formed from nitrogen-polarity first lateral regions of the layer and pyramids are not formed in an adjacent second lateral region of the layer, the second lateral region being located between the first lateral regions; and

wherein the fabricated structure has a metallic electrode located on a flat surface of the second lateral region of the layer.

2. The method of claim 1, wherein the subjecting does not significantly etch a portion of the top surface of the layer that has metal-polarity.

3. The method of claim 1, wherein the group III-nitride comprises gallium.

4. The method of claim 1, wherein the act of forming includes epitaxially growing the layer.

5. The method of claim 1, wherein the layer comprises gallium nitride.

6. The method of claim 1, wherein the pyramids spatially overlap.

7. The method of claim 1, wherein tips of the pyramids have an irregular spatial distribution.

8. The method of claim 1, wherein tips of the pyramids have a random spatial distribution.

9. The method of claim 1, wherein the pyramids are physically separated from any electrode.

10. The method of claim 1, wherein a portion of the layer of the group III-nitride is located on the layer of another group III-nitride alloy.

11. The method of claim 1, further comprising forming a metal electrode on a portion of a surface of the layer.

12. The method of claim 11, wherein the electrode is located on a flat portion of the top surface.