Light-emitting device with high light extraction

• US 9,530,940 B2
• Filed: 01/05/2015
• Issued: 12/27/2016
• Est. Priority Date: 10/19/2005
• Status: Active Grant

• Current Assignee: Epistar Corporation
• Original Assignee: Epistar Corporation
• Inventors: Hsu, Tzu-Chieh, Tao, Ching-San, Ou, Chen, Hsieh, Min-Hsun, Chen, Chao-Hsing
• Primary Examiner(s): Bowman, Mary Ellen
• Application Number:
  US14/589,683
• Publication Number:
  US 20150137167A1
• Time in Patent Office: 722 Days
• US Class Current: 1/1
• CPC Class Codes: H01L 33/10 with a light reflecting structure, e.g. semiconductor Bragg reflector
• CPC Class Codes: H01L 33/105 with a resonant cavity structure
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/382 the electrode extending partially in or entirely through the semiconductor body
• CPC Class Codes: H01L 33/405 Reflective materials
• CPC Class Codes: H01L 33/42 Transparent materials

Abstract

A light-emitting device, comprises a light-emitting stacked layer comprising a first conductivity type semiconductor layer; a light-emitting layer formed on the first conductivity type semiconductor layer; and a second conductivity type semiconductor layer formed on the light-emitting layer and comprising a first plurality of cavities; a first planarization layer formed on a first part of the second conductivity type semiconductor layer; a first transparent conductive oxide layer formed on the first planarization layer and on a second part of the second conductivity type semiconductor layer, the first transparent conductive oxide layer including a first portion in contact with the first planarization layer and including a second portion in contact with the upper surface of the second conductivity type semiconductor layer; a first electrode formed on the first portion; and a first reflective metal layer formed between the first transparent conductive oxide layer and the first electrode.

Claims

1. A light-emitting device comprising:

a light-emitting stacked layer comprising a first conductivity type semiconductor layer;

a light-emitting layer formed on the first conductivity type semiconductor layer; and

a second conductivity type semiconductor layer formed on the light-emitting layer and comprising a first plurality of cavities such that an upper surface of the second conductivity type semiconductor layer is a textured surface;

a first planarization layer formed on a first part of the second conductivity type semiconductor layer;

a first transparent conductive oxide layer formed on the first planarization layer and on a second part of the second conductivity type semiconductor layer, the first transparent conductive oxide layer including a first portion in contact with the first planarization layer and including a second portion in contact with the upper surface of the second conductivity type semiconductor layer;

a first electrode formed on the first portion of the first transparent conductive oxide layer; and

a first reflective metal layer formed between the first transparent conductive oxide layer and the first electrode.

2. The light-emitting device according to claim 1, wherein the first transparent conductive oxide layer further comprises a second plurality of cavities such that an upper surface of the second portion of the first transparent conductive oxide layer is a textured surface.

3. The light-emitting device according to claim 2, wherein the first plurality of cavities and the second plurality of cavities are shaped into cones or pyramids.

4. The light-emitting device according to claim 1, further comprising a substrate formed below the light-emitting stacked layer.

5. The light-emitting device according to claim 4, further comprising a bonding layer formed between the light-emitting stacked layer and the substrate.

6. The light-emitting device according to claim 5, further comprising a third transparent conductive oxide layer formed between the light-emitting stacked layer and the bonding layer.

7. The light-emitting device according to claim 1, wherein the material of the first transparent conductive oxide layer is selected form the group consisting of indium tin oxide (ITO), cadmium tin oxide (CTO), antimony tin oxide, zinc indium oxide, aluminum zinc oxide, zinc antimony oxide, and the combinations thereof.

8. The light-emitting device according to claim 1, wherein the first planarization layer is substantially flat and comprises spin-on-glass (SOG) material or benzocyclobutene (BCB).

9. The light-emitting device according to claim 8, wherein the SOG material comprises a dielectric material.

10. The light-emitting device according to claim 1, wherein the material of the light-emitting stacked layer contains one or more elements selected from the group consisting of Ga, Al, In, As, P, N and Si.

11. The light-emitting device according to claim 1, wherein the area of the first reflective metal layer is substantially the same as the area of the first electrode.

12. A light-emitting device comprising:

a light-emitting stacked layer comprising a first conductivity type semiconductor layer;

a light-emitting layer formed on the first conductivity type semiconductor layer; and

a second conductivity type semiconductor layer formed on the light-emitting layer and comprising a first plurality of cavities such that an upper surface of the second conductivity type semiconductor layer is a textured surface;

a first planarization layer formed on a first part of the second conductivity type semiconductor layer;

a first transparent conductive oxide layer formed on the first planarization layer and on a second part of the second conductivity type semiconductor layer, the first transparent conductive oxide layer including a first portion in contact with the first planarization layer and including a second portion in contact with the second conductivity type semiconductor layer; and

a first electrode formed on the first portion of the first transparent conductive oxide layer,

wherein the first transparent conductive oxide layer further has a secondary branch not covered by the first electrode and extending toward an end of the light emitting device.

13. The light-emitting device according to claim 12, wherein the first transparent conductive oxide layer further has a third branch extending from the secondary branch and not covered by the first electrode.

14. A light-emitting device comprising:

a light-emitting stacked layer comprising a first conductivity type semiconductor layer comprising a third plurality of cavities such that an upper surface of the first conductivity type semiconductor layer is a textured surface;

a light-emitting layer formed on the first conductivity type semiconductor layer; and

a second conductivity type semiconductor layer formed on the light-emitting layer and comprising a first plurality of cavities such that an upper surface of the second conductivity type semiconductor layer is a textured surface;

a first planarization layer formed on a first part of the second conductivity type semiconductor layer;

a first transparent conductive oxide layer formed on the first planarization layer and on a second part of the second conductivity type semiconductor layer, first transparent conductive oxide layer including a first portion in contact with the first planarization layer and including a second portion in contact with the second conductivity type semiconductor layer;

a first electrode formed on the first portion of the first transparent conductive oxide layer; and

a second planarization layer formed on a first part of an upper surface of the first conductivity type semiconductor layer; and

a second transparent conductive oxide layer formed on the second planarization layer and on a second part of the first conductivity type semiconductor layer, the second transparent conductive oxide layer including a first portion in contact with the second planarization layer and including a second portion in contact with the first conductivity type semiconductor layer.

15. The light-emitting device according to claim 14, wherein the second planarization layer is substantially flat and comprises spin-on-glass (SOG) material or benzocyclobutene (BCB).

16. The light-emitting device according to claim 15, wherein the second transparent conductive oxide layer further comprises a fourth plurality of cavities such that an upper surface of the second portion of the second transparent conductive oxide layer is a textured surface.

17. The light-emitting device according to claim 16, wherein the third plurality of cavities and the fourth plurality of cavities are shaped into cones or pyramids.

18. The light-emitting device according to claim 14, further comprising a second electrode formed on the first portion of the second transparent conductive oxide layer.

19. The light-emitting device according to claim 18, further comprising a second reflective metal layer formed between the second electrode and the second transparent conductive oxide layer.