LIGHT-EMITTING DEVICE

• US 20130026519A1
• Filed: 02/17/2012
• Published: 01/31/2013
• Est. Priority Date: 07/25/2011
• Status: Active Grant

• Current Assignee: Epistar Corporation (Ennostar, Inc.)
• Original Assignee: Huga Optotech Incorporated (Ennostar, Inc.)
• Inventors: Huang, Yu-Min, Wu, Kuo-Chen, Li, Jun-Sheng
• Granted Patent: US 8,987,761 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• 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 33/42 Transparent materials
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector

Abstract

A structure of a light-emitting device includes the following components: a substrate; an epitaxial structure on the substrate, the epitaxial structure including at least a first conductivity type semiconductor layer, a light-emitting active layer, and a second conductivity type semiconductor layer; a first electrode on the first conductivity type semiconductor layer; a transparent conductive layer between the first electrode and the first conductivity type semiconductor layer; and a three-dimensional distributed Bragg reflector (DBR) layer between the transparent conductive layer and the first conductivity type semiconductor layer.

Claims

1. A light-emitting device, comprising:

a substrate;

an epitaxial structure on the substrate, wherein the epitaxial structure comprises at least a first conductivity type semiconductor layer, a light-emitting active layer, and a second conductivity type semiconductor layer;

a first electrode on the first conductivity type semiconductor layer;

a transparent conductive layer between the first electrode and the first conductivity type semiconductor layer; and

a three-dimensional distributed Bragg reflector (DBR) layer between the transparent conductive layer and the first conductivity type semiconductor layer.

2. The light-emitting device according to claim 1, wherein the first conductivity type is P type and the second conductivity type is N type.

3. The light-emitting device according to claim 1, wherein a reflector is disposed on the bottom of the substrate, wherein the bottom is opposed to the side of the first electrode.

4. The light-emitting device according to claim 1, wherein the three-dimensional DBR layer is located under the first electrode only.

5. The light-emitting device according to claim 1, wherein the epitaxial structure comprises a plurality of pillar structures.

6. The light-emitting device according to claim 5, wherein the pillar structures are formed under the first electrode only.

7. The light-emitting device according to claim 5 wherein the three-dimensional DBR layer is situated on a surface of the pillar structures.

8. The light-emitting device according to claim 5, wherein the plurality of pillar structures is disposed under the first electrode only.

9. The light-emitting device according to claim 5, wherein there are recessed trenches between the pillar structures.

10. The light-emitting device according to claim 9, wherein a depth of the recessed trench is selected from the group consisting of:

the depth of the recessed trench is deeper than that of the light-emitting active layer, and extending to the second conductivity type semiconductor layer;

the depth of the recessed trench does not exceed a thickness of the first conductivity type semiconductor layer; and

the depth of the recessed trench does not exceed a combined thickness of first conductivity type semiconductor layer and the light-emitting active layer.

11. The light-emitting device according to claim 5, wherein each of the pillar structure has oblique sidewalls, and an acute angle θ

between the oblique sidewalls and a bottom surface of the recessed trench ranges between 35° and

80°

.

12. The light-emitting device according to claim 1, wherein the first electrode further comprises a branch electrode.

13. The light-emitting device according to claim 12, wherein the transparent conductive layer overlaps with the branch electrode only;

and the first electrode directly contacts with the three-dimensional DBR layer.

14. The light-emitting device according to claim 12, wherein the transparent conductive layer overlaps with a peripheral edge of the branch electrode only.

15. A light-emitting device, comprising:

a substrate;

an epitaxial structure on the substrate, wherein the epitaxial structure comprises at least a first conductivity type semiconductor layer, a light-emitting active layer, and a second conductivity type semiconductor layer;

a first electrode on the first conductivity type semiconductor layer;

a transparent conductive layer between the first electrode and the first conductivity type semiconductor layer; and

a Bragg reflector (DBR) layer between the transparent conductive layer and the first electrode.

16. The light-emitting device according to claim 15, wherein the epitaxial structure comprises a plurality of pillar structures.

17. The light-emitting device according to claim 16, wherein the pillar structures are formed under the first electrode only.

18. The light-emitting device according to claim 16, wherein the transparent conductive layer is formed on a surface of the plurality of pillar structures.

19. The light-emitting device according to claim 16, wherein there are recessed trenches between the pillar structures.

20. The light-emitting device according to claim 19, wherein a depth of the recessed trenches does not exceed a thickness of the first conductivity type semiconductor layer.