Light-emitting diode structure

• US 9,117,968 B2
• Filed: 03/15/2013
• Issued: 08/25/2015
• Est. Priority Date: 04/26/2011
• Status: Active Grant

• Current Assignee: Epistar Corporation (Ennostar, Inc.)
• Original Assignee: TSMC Solid State Lighting Ltd. (Ennostar, Inc.)
• Inventors: Hsia, Hsing-Kuo, Chiu, Ching-Hua
• Primary Examiner(s): Tran, Tan N
• Application Number:
  US13/834,055
• Publication Number:
  US 20150194567A1
• Time in Patent Office: 893 Days
• Field of Search: 257/13, 257/95, 257/98, 257/100
• US Class Current: 1/1
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate

Abstract

A light-emitting diode structure includes an AuSn or AuIn-containing bonding layer over a substrate, a metal layer disposed over the bonding layer, a p-type doped gallium nitride (p-GaN) layer disposed over the metal layer, a n-type doped gallium nitride (n-GaN) layer approximate the p-GaN layer, a multiple quantum well structure disposed between the n-GaN and p-GaN layers, and a conductive contact disposed on the n-GaN layer. The n-GaN layer includes a rough surface with randomly distributed dips. The nano-sized dips have diameters distributed between about 100 nm and about 600 nm, have a dip density ranging from about 107 grains/cm² to about 109 grains/cm², and are spaced from each other with an average spacing S, average diameter D, and a ratio S/D that ranges between about 1.1 and about 1.5. The conductive contact is disposed on some of the nano-sized dips of the rough surface.

Claims

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

a bonding layer disposed over a substrate, wherein the bonding layer contains AuSn or AuIn;

a metal layer disposed over the bonding layer;

a p-type doped gallium nitride (p-GaN) layer disposed over the metal layer;

a n-type doped gallium nitride (n-GaN) layer approximate the p-GaN layer;

a multiple quantum well (MQW) structure disposed between the n-GaN layer and the p-GaN layer; and

a conductive contact disposed on the n-GaN layer;

wherein the n-GaN layer includes a rough surface with randomly distributed nano-sized dips, wherein the nano-sized dips have diameters distributed between about 100 nm and about 600 nm and a dip density ranging from about 10⁷ grains/cm² to about 10⁹ grains/cm², wherein the nano-sized dips are spaced from each other with an average spacing S and an average diameter D, wherein a ratio of S/D ranges between about 1.1 and about 1.5, and wherein the conductive contact is disposed on some of the nano-sized dips of the rough surface.

2. The LED structure of claim 1, wherein the substrate includes one of a silicon wafer and a metal plate.

3. The LED structure of claim 1, further comprising a high reflective metal film disposed between the substrate and the p-GaN layer.

4. A light-emitting diode (LED) structure, comprising:

a substrate;

a bonding layer disposed over the substrate, wherein the bonding layer contains AuSn or AuIn;

a metal layer disposed over the bonding layer;

a first doped gallium nitride layer disposed over the metal layer;

a multiple quantum well (MQW) structure disposed over the first doped gallium nitride layer;

a second doped gallium nitride layer disposed over the MQW structure, wherein the second doped gallium nitride layer has a roughened surface that includes a plurality of nano-sized dips, wherein the nano-sized dips have diameters distributed between about 100 nm and about 600 nm and a dip density ranging from about 10⁷ grains/cm² to about 10⁹ grains/cm², wherein the nano-sized dips are spaced from each other with an average spacing S and an average diameter D, wherein a ratio of S/D ranges between about 1.1 and about 1.5; and

a metal contact disposed on at least some of the nano-sized dips of the roughened surface.

5. The LED structure of claim 4, wherein the nano-sized dips are randomly distributed.

6. The LED structure of claim 4, further comprising one or more trenches that extend at least partially though the first and second doped gallium nitride layers and the MQW structure.

7. The LED structure of claim 4, further comprising a reflective layer disposed between the substrate and the first doped gallium nitride layer.

8. The LED structure of claim 4, wherein the substrate includes a silicon wafer or a metal plate.

9. A light-emitting diode (LED) structure, comprising:

a substrate;

a bonding layer disposed over the substrate, wherein the bonding layer contains AuSn or AuIn;

a metal layer disposed over the bonding layer;

a first doped semiconductor layer disposed over the metal layer;

a light-emitting layer disposed over the first doped semiconductor layer;

a second doped semiconductor layer disposed over the light-emitting layer, wherein the first and second doped semiconductor layers have different types of conductivity, and wherein the second doped semiconductor layer includes a rough surface with a plurality of miniature-sized dips, wherein the miniature-sized dips have diameters distributed between about 100 nm and about 600 nm and a dip density ranging from about 10⁷ grains/cm² to about 10⁹ grains/cm², wherein the miniature-sized dips are spaced from each other with an average spacing S and an average diameter D, wherein a ratio of S/D ranges between about 1.1 and about 1.5; and

a metal pad disposed on some of the miniature-sized dips of the roughened surface.

10. The LED structure of claim 9, wherein the miniature-sized dips are randomly distributed.

11. The LED structure of claim 9, wherein the first and second doped semiconductor layers each include gallium nitride.

12. The LED structure of claim 9, wherein:

the first doped semiconductor layer is a p-type layer; and

the second doped semiconductor layer is an n-type layer.

13. The LED structure of claim 9, wherein the substrate includes a silicon wafer or a metal plate.