Group III-nitride layers with patterned surfaces

• US 6,986,693 B2
• Filed: 03/26/2003
• Issued: 01/17/2006
• Est. Priority Date: 03/26/2003
• Status: Active Grant

• Current Assignee: Alcatel-Lucent SA (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Chowdhury, Aref, Ng, Hock Min, Slusher, Richart Elliott
• Primary Examiner(s): WILLIAMS, JOSEPH L
• Application Number:
  US10/397,799
• Publication Number:
  US 20040189173A1
• Time in Patent Office: 1,028 Days
• Field of Search: 445/49, 445/50, 445/51, 438/46, 438/47, 438/22, 438/93, 438/94, 438/172, 438/602, 438/604, 438/606
• US Class Current: 445/49
• 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, comprising:

providing a crystalline substrate with a planar surface;

forming a first layer of a first group III-nitride on the planar surface, the first layer having a single polarity and having a pattern of holes or trenches that expose a portion of the substrate;

then, epitaxially growing a second layer of a second group III-nitride on the first layer and the exposed portion of substrate, the first and second group III-nitrides having different alloy compositions; and

subjecting the second layer to a solution of base to mechanically pattern the second layer such that the solution etches the portion of the second layer on the first layer differently than the portion of the second layer on the substrate.

2. The method of claim 1, wherein the single polarity is group III metal-polarity.

3. The method of claim 2, wherein one of the group III-nitrides comprises aluminum and the other of the group III-nitride comprises gallium.

4. The method of claim 1, wherein the act of epitaxially growing produces one polarity of the second group III-nitride on the first group III-nitride and an opposite polarity of the second group III-nitride on the exposed portion of substrate.

5. The method of claim 1, wherein the second layer consists of first and second regions, the first region being located on the exposed portion of the substrate and the second region being located on the first layer;

and

wherein the subjecting produces pyramids in one of the first and second regions and produces a smooth layer in the other of the first and second regions.

6. The method of claim 5, wherein the first group III-nitride is disposed between the planar surface and the second regions.

7. The method of claim 1, wherein the subjecting produces an array of columnar holes or trenches in the second layer of a second group III-nitride.

8. The method of claim 7, wherein at least some of the columnar holes or trenches uncover a portion of the planar surface of the substrate.

9. The method of claim 7, wherein the array forms a pattern with at least one discrete lattice symmetry.

10. The method of claim 1, wherein the single polarity is metal-polarity.

11. The method of claim 10, wherein the act of epitaxially growing produces one polarity of the second group III-nitride ever on the first group III-nitride and an opposite polarity of the second group III-nitride on the exposed portion of substrate.

12. The method of claim 10, wherein the second layer consists of first and second regions, the first region being located on the exposed portion of the substrate and the second region being located on the first layer;

and

wherein the subjecting produces pyramids in one of the first and second regions and produces a smooth layer in the other of the first and second regions.