Contacts for an n-type gallium and nitrogen substrate for optical devices

• US 8,994,033 B2
• Filed: 07/09/2013
• Issued: 03/31/2015
• Est. Priority Date: 07/09/2013
• Status: Active Grant

• Current Assignee: Korrus Incorporated (MKD Electric, Inc.)
• Original Assignee: Soraa, Inc.
• Inventors: Cich, Michael J., Thomson, Kenneth John
• Primary Examiner(s): Valentine, Jami M
• Application Number:
  US13/937,338
• Publication Number:
  US 20150014695A1
• Time in Patent Office: 630 Days
• Field of Search: 257/13, 257/76, 257/33.012, 438/46, 438/34
• US Class Current: 257/76
• CPC Class Codes: H01L 2933/0008 Processes
• CPC Class Codes: H01L 2933/0016 relating to electrodes
• CPC Class Codes: H01L 2933/0033 relating to semiconductor body packages
• CPC Class Codes: H01L 33/0075 comprising nitride compounds
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/38 with a particular shape
• CPC Class Codes: H01L 33/382 the electrode extending partially in or entirely through the semiconductor body
• CPC Class Codes: H01L 33/40 Materials therefor
• CPC Class Codes: H01L 33/405 Reflective materials

Abstract

A method for fabricating LED devices. The method includes providing a gallium and nitrogen containing substrate member (e.g., GaN) comprising a backside surface and a front side surface. The method includes subjecting the backside surface to a polishing process, causing a backside surface to be characterized by a surface roughness, subjecting the backside surface to an anisotropic etching process exposing various crystal planes to form a plurality of pyramid-like structures distributed spatially in a non-periodic manner on the backside surface, treating the backside surface comprising the plurality of pyramid-like structures, to a plasma species, and subjecting the backside surface to a surface treatment. The method further includes forming a contact material comprising an aluminum bearing species or a titanium bearing species overlying the surface-treated backside to form a plurality of LED devices with the contact material.

Claims

1. A light emitting diode (LED) device, comprising:

a gallium and nitrogen containing substrate member comprising a backside surface and a front side surface, the front side surface comprising an n-type material overlying the substrate member, an active region overlying the n-type material, and a p-type material overlying the active region; and

a plurality of pyramid-like structures distributed spatially in a non-periodic manner on the backside surface; and

a contact material comprising an aluminum bearing species or a titanium bearing species overlying the plurality of pyramid-like structures,

wherein the plurality of pyramid like structures comprises a surface treated with a plasma species followed by treatment with an acid.

2. The device of claim 1, wherein the backside surface is characterized by a nitrogen face of a c-plane and an n-type GaN with a carrier concentration from 1E15/cm³ to 1 E20/cm³.

3. The device of claim 1, wherein each of the plurality of pyramid-like structures is characterized by a height from 20 nm to 1000 nm.

4. The device of claim 1, wherein the active region is configured to emit electromagnetic radiation in a range of 450 nm to 480 nm.

5. The device of claim 1, wherein the active region comprises a plurality of quantum well structures.

6. The device of claim 1, wherein each of the plurality of pyramid-like structures comprises three sides.

7. The device of claim 1, wherein each of the plurality of pyramid-like structures comprises two or more sides.

8. The device of claim 1, wherein the plasma species is a SiCl₄ plasma.

9. The device of claim 1, wherein the acid is hydrochloric acid.