Vertical light emitting diode (VLED) dice having confinement layers with roughened surfaces and methods of fabrication

• US 9,130,114 B2
• Filed: 05/16/2013
• Issued: 09/08/2015
• Est. Priority Date: 01/11/2005
• Status: Active Grant

• Current Assignee: Semileds Optoelectronics Company Limited (SemiLEDs Inc)
• Original Assignee: Semileds Optoelectronics Company Limited (SemiLEDs Inc)
• Inventors: Chu, Chen-Fu, Liu, Wen-Huang, Cheng, Chao-Chen, Doan, David Trung, Wen, Yang Po, Cheng, Hao-Chung, Fan, Feng-Hsu
• Primary Examiner(s): Pham, Thanh V
• Application Number:
  US13/895,421
• Publication Number:
  US 20140339496A1
• Time in Patent Office: 845 Days
• US Class Current: 1/1
• CPC Class Codes: H01L 2924/12041 LED
• 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 33/0095 Post-treatment of devices, e.g. annealing, recrystallisation or short-circuit elimination
• CPC Class Codes: H01L 33/04 with a quantum effect structure or superlattice, e.g. tunnel junction
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers

Abstract

A vertical light emitting diode (VLED) die includes an epitaxial structure having a first-type confinement layer, an active layer on the first-type confinement layer configured as a multiple quantum well (MQW) configured to emit light, and a second-type confinement layer having a roughened surface. In a first embodiment, the roughened surface includes a pattern of holes with a depth (d) in a major surface thereof surrounded by a pattern of protuberances with a height (h) on the major surface. In a second embodiment, the roughened surface includes a pattern of primary protuberances surrounded by a pattern of secondary protuberances.

Claims

1. A vertical light emitting diode (VLED) die comprising:

a first-type confinement layer;

an active layer on the first-type confinement layer comprising a multiple quantum well (MQW) configured to emit light; and

a second-type confinement layer comprising a roughened surface having a major surface, the roughened surface comprising a hole pattern and a separate protuberance pattern surrounding the hole pattern, the hole pattern comprising a plurality of holes in the major surface, each hole having a first geometrical shape and a depth (d) in the major surface, the protuberance pattern comprising a plurality of protuberances on the major surface, each protuberance having a second geometrical shape and a height (h) on the major surface.

2. The vertical light emitting diode (VLED) die of claim 1 wherein each hole includes a bottom surface having a plurality of second protuberances.

3. The vertical light emitting diode (VLED) die of claim 1 wherein each hole has a generally hexagonal peripheral shape.

4. The vertical light emitting diode (VLED) die of claim 1 wherein each hole has a shape selected from the group consisting of circular, square, rectangular, oval and polygonal.

5. The vertical light emitting diode (VLED) die of claim 1 wherein each protuberance has a generally pyramidal, truncated pyramidal or ziggurat shape.

6. The vertical light emitting diode (VLED) die of claim 1 wherein the protuberances have sidewalls at an angle greater than 90°

with respect to the major surface.

7. The vertical light emitting diode (VLED) die of claim 1 wherein the protuberances include a plurality of first protuberances having a first height and a plurality of second protuberances having a second height.

8. The vertical light emitting diode (VLED) die of claim 1 wherein the first-type confinement layer comprises a p-type semiconductor layer and the second-type confinement layer comprises an n-type semiconductor layer.

9. A vertical light emitting diode (VLED) die comprising:

a first-type confinement layer;

an active layer on the first-type confinement layer comprising a multiple quantum well (MQW) configured to emit light; and

a second-type confinement layer comprising a roughened surface having a major surface, the roughened surface comprising a hole pattern and a separate protuberance pattern surrounding the hole pattern, the hole pattern comprising a plurality of holes in the major surface, each hole having a selected peripheral shape and a depth (d) in the major surface, the protuberance pattern comprising a plurality of protuberances on the major surface, each protuberance having a generally pyramidal shape and a height (h) on the major surface.

10. The vertical light emitting diode (VLED) die of claim 9 wherein the selected peripheral shape comprises hexagonal.

11. The vertical light emitting diode (VLED) die of claim 9 wherein the selected peripheral shape comprises circular.

12. The vertical light emitting diode (VLED) die of claim 9 wherein the selected peripheral shape comprises polygonal.

13. The vertical light emitting diode (VLED) die of claim 9 wherein the selected peripheral shape comprises oval.

14. A vertical light emitting diode (VLED) die comprising:

a first-type confinement layer;

an active layer on the first-type confinement layer comprising a multiple quantum well (MQW) configured to emit light; and

a second-type confinement layer comprising a roughened surface having a major surface, the roughened surface comprising a hole pattern and a separate protuberance pattern surrounding the hole pattern, the hole pattern comprising a plurality of holes in the major surface, each hole having a selected peripheral shape, sidewalls and a bottom surface to a depth (d) in the major surface, the protuberance pattern comprising a plurality of protuberances on the major surface, each protuberance having a generally pyramidal shape and a height (h) on the major surface.

15. The vertical light emitting diode (VLED) die of claim 14 wherein each hole includes a plurality of second protuberances on the bottom surface.