High-efficiency light-emitting device and manufacturing method thereof

• US 20080157115A1
• Filed: 03/04/2008
• Published: 07/03/2008
• Est. Priority Date: 06/21/2005
• Status: Active Grant

• Current Assignee: Epistar Corporation
• Original Assignee: Epistar Corporation
• Inventors: Chang, Chia-Chen, Huo, Donald Tai-Chan, Yang, Tzu-Ling, Ou, Chen, Chuang, Chia-Ming
• Granted Patent: US 8,097,897 B2
• Time in Patent Office: Days
• US Class Current: 257/99
• CPC Class Codes: H01L 33/10 with a light reflecting structure, e.g. semiconductor Bragg reflector
• CPC Class Codes: H01L 33/145 with a current-blocking structure
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers

Abstract

This invention provides a high-efficiency light-emitting device and the manufacturing method thereof. The high-efficiency light-emitting device includes a substrate; a reflective layer; a bonding layer; a first semiconductor layer; an active layer; and a second semiconductor layer formed on the active layer. The second semiconductor layer includes a first surface having a first lower region and a first higher region.

Claims

1. A high-efficiency light-emitting device comprising:

a substrate;

a first semiconductor layer formed on the substrate;

an active layer formed on the first semiconductor layer; and

a second semiconductor formed on the active layer having a first surface composed of a first lower region and a first higher region wherein the first surface is away from the active layer and wherein a roughness of the first lower region is less than that of the first higher region.

2. The high-efficiency light-emitting device according to claim 1, wherein the first higher region has an uneven surface selected form a group consisting of a first plurality of hexagonal-pyramid cavities, a plurality of convexes, and a plurality of concaves.

3. The high-efficiency light-emitting device according to claim 1, wherein a surface of the first lower region comprises a flat surface.

4. The high-efficiency light-emitting device according to claim 1, further comprising a bonding layer formed in-between the first semiconductor layer and the substrate and a reflective layer formed in-between the bonding layer and the substrate.

5. The high-efficiency light-emitting device according to claim 1, wherein a depth from the first higher region to the first lower region is about 100 nm˜

1 μ

m.

6. The high-efficiency light-emitting device according to claim 1, further comprising a first electrode located on the first lower region.

7. The high-efficiency light-emitting device according to claim 1, further comprising:

a first current blocking layer formed on the first lower region;

a first current spreading layer formed on the second semiconductor layer and the first current blocking layer, wherein the first current spreading layer covers at least a portion of the first surface; and

a first electrode formed on the first current spreading layer and located right above the first lower region layer.

8. The high-efficiency light-emitting device according to claim 7, wherein a material of the first current blocking layer is selected from a group consisting of dielectric materials, Su8, BCB, PFCB, epoxy, Acrylic Resin, COC, PMMA, PET, PC, polyetherimide, fluorocarbon polymer, silicone, glass, Al₂O₃, SiO₂, SiN_x, SiO₂, TiO₂, insulating material, and the combination thereof.

9. The high-efficiency light-emitting device according to claim 7, wherein a material of the first current spreading layer is selected from a group consisting of GaP, ITO, InO, SnO, CTO, ATO, ZnO, and the combination thereof.

10. The high-efficiency light-emitting device according to claim 1, wherein the first semiconductor layer comprises a second surface composed of a second lower region and a second higher region, wherein the second surface is close to the active layer and wherein a roughness of the second lower region is less than that of the second higher region.

11. The high-efficiency light-emitting device according to claim 10, wherein a depth from the second higher region to the second lower region is about 100 mm˜

1 μ

m.

12. The high-efficiency light-emitting device according to claim 10, wherein the second higher region has an uneven surface selected form a group consisting of a second plurality of hexagonal-pyramid cavities, a plurality of convexes, and a plurality of concaves.

13. The high-efficiency light-emitting device according to claim 10, wherein a surface of the second lower region comprises a flat surface.

14. The high-efficiency light-emitting device according to claim 10, further comprising a second electrode formed on the second lower region.

15. The high-efficiency light-emitting device according to claim 10, further comprising:

a second current blocking layer formed on the second lower region;

a second current spreading layer formed on the first semiconductor layer and the second current blocking layer, wherein the second current spreading layer covers at least a portion of the second surface; and

a second electrode formed on the second current spreading layer and located right above the second lower region.

16. The high-efficiency light-emitting device according to claim 15, wherein a material of the second current blocking layer is selected from a group consisting of dielectric materials, Su8, BCB, PFCB, epoxy, Acrylic Resin, COC, PMMA, PET, PC, polyetherimide, fluorocarbon polymer, silicone, glass, Al₂O₃, SiO₂, SiN_x, SiO₂, TiO₂, insulating material, and the combination thereof.

17. The high-efficiency light-emitting device according to claim 15, wherein a material of the second current spreading layer is selected from a group consisting of GaP, ITO, InO, SnO, CTO, ATO, ZnO, and the combination thereof.

18. A method of manufacturing the high-efficiency light-emitting device comprising the steps of:

providing a substrate;

forming a first semiconductor layer on the substrate;

forming an active layer on the first semiconductor layer;

forming a second semiconductor layer having a first surface on the active layer wherein the first surface is away from the active layer; and

forming a first lower region and a first higher region on the first surface wherein a roughness of the first lower region is less than that of the first higher region.

19. The method of manufacturing the high-efficiency light-emitting device according to claim 18, wherein a depth from the first higher region to the first lower region is about 100 mm˜

1 μ

m.

20. The method of manufacturing the high-efficiency light-emitting device according to claim 18, further comprising roughening the first surface before forming the first lower region.

21. The method of manufacturing the high-efficiency light-emitting device according to claim 18, further comprising forming a first electrode on the first lower region after forming the first lower region on the first surface.

22. The method of manufacturing the high-efficiency light-emitting device according to claim 18, after forming the first lower region on the first surface, further comprising the steps of:

forming a first current blocking layer on the first lower region;

forming a first current spreading layer on the second semiconductor layer and the first current blocking layer, wherein the first current spreading layer covers at least a portion of the first surface; and

forming a first electrode on the first current spreading layer, wherein the first electrode is located right above the first lower region.

23. The method of manufacturing the high-efficiency light-emitting device according to claim 18, wherein a method of forming the first lower region on the first surface is selected from a group consisting of etching, Chemical Mechanical Polishing, and Inductively Coupled Plasma.

24. The method of manufacturing the high-efficiency light-emitting device according to claim 18, after forming the second semiconductor layer on the active layer, further comprising the steps of:

removing a portion of the second semiconductor layer, the active layer, and the first semiconductor layer to expose a second surface of the first semiconductor layer, wherein the second surface is close to the active layer; and

forming a second lower region and a second higher region on the second surface, wherein a roughness of the second lower region is less than that of the second higher region.

25. The method of manufacturing the high-efficiency light-emitting device according to claim 24, wherein a depth from the second higher region to the second lower region is about 100 mm˜

1 μ

m

26. The method of manufacturing the high-efficiency light-emitting device according to claim 24, further comprising roughening the second surface before forming the second lower region and the second higher region on the second surface.

27. The method of manufacturing the high-efficiency light-emitting device according to claim 24, further comprising forming a second electrode on the second lower region after forming the second lower region and the second higher region on the second surface.

28. The method of manufacturing the high-efficiency light-emitting device according to claim 24, after forming the second lower region and the second higher region on the second surface of the first semiconductor, further comprising steps of:

forming a second current blocking layer on the second lower region;

forming a second current spreading layer on the first semiconductor layer and the second current blocking layer, wherein the second current spreading layer covers at least a portion of the second surface; and

forming a second electrode on the second current spreading layer, wherein the second electrode is located right above the second lower region.

29. The method of manufacturing the high-efficiency light-emitting device according to claim 24, wherein a method of forming the second lower region and the second higher region on the second surface is selected from a group consisting of etching, Chemical Mechanical Polishing, and Inductively Coupled Plasma.

30. The method of manufacturing the high-efficiency light-emitting element according to claim 18, before forming a first semiconductor layer on the substrate, further comprising forming a reflective layer in-between the substrate and the first semiconductor layer and a bonding layer in-between the first semiconductor layer and the reflective layer.