Semiconductor light-emitting device

• US 7,804,101 B2
• Filed: 07/23/2004
• Issued: 09/28/2010
• Est. Priority Date: 07/24/2001
• Status: Expired due to Fees

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Corporation
• Inventors: Sano, Masahiko, Niki, Isamu, Shioji, Shuji, Yamada, Motokazu
• Primary Examiner(s): Sefer; A.
• Application Number:
  US10/897,163
• Publication Number:
  US 20050001227A1
• Time in Patent Office: 2,258 Days
• Field of Search: 257/95, 257/98, 257/103, 257/117, 257/594
• US Class Current: 257/98
• CPC Class Codes: H01L 21/02378 Silicon carbide
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/02647 Lateral overgrowth
• CPC Class Codes: H01L 2933/0083 Periodic patterns for optical field-shaping in or on the semiconductor body or semiconductor body package, e.g. photonic bandgap structures
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: H01L 33/16 with a particular crystal structure or orientation, e.g. polycrystalline, amorphous or porous
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/24 of the light emitting region, e.g. non-planar junction
• CPC Class Codes: H01L 33/26 Materials of the light emitting region
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/38 with a particular shape
• CPC Class Codes: Y10T 428/24355 Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.]
• CPC Class Codes: Y10T 428/24479 including variation in thickness

Abstract

A semiconductor light emitting device including a substrate, an electrode and a light emitting region is provided. The substrate may have protruding portions formed in a repeating pattern on substantially an entire surface of the substrate while the rest of the surface may be substantially flat. The cross sections of the protruding portions taken along planes orthogonal to the surface of the substrate may be semi-circular in shape. The cross sections of the protruding portions may in alternative be convex in shape. A buffer layer and a GaN layer may be formed on the substrate.

Claims

1. A semiconductor light emitting diode comprising a substrate, an ohmic electrode and a plurality of semiconductor layers and configured so that light generated in said plurality of semiconductor layers is emitted from said ohmic electrode or from said substrate,

wherein said substrate comprises sapphire,

protruding portions are formed in a repeating pattern within a surface of the substrate so as to define a polygon as the repeating pattern in plan view of the substrate while the rest of the surface is substantially flat so as to scatter or diffract light generated in said semiconductor layers, and

cross sections of the protruding portions taken along planes orthogonal to the surface of the substrate are semi-circular in shape.

2. The semiconductor light emitting diode of claim 1, wherein a pitch of the protruding portions is less than 50 micrometers.

3. The semiconductor light emitting diode of claim 2, wherein a pitch of the protruding portions is less than 10 micrometers.

4. The semiconductor light emitting diode of claim 3, wherein an edge or a corner of one of the protruding portions is rounded in a plan view.

5. The semiconductor light emitting diode of claim 4, wherein the shape of the protruding portions, in a plan view, is circular.

6. The semiconductor light emitting diode of claim 1, wherein the semiconductor layers comprise a n-side semiconductor layer, a p-side semiconductor layer and an active layer interposed between the n-side semiconductor layer and p-side semiconductor layer.

7. The semiconductor light emitting diode of claim 6, wherein the sequence of the semiconductor layers is n-side semiconductor layer/active layer/p-side semiconductor layer or p-side semiconductor layer/active layer/n-side semiconductor layer.

8. The semiconductor light emitting diode of claim 7, wherein said active layer comprises InGaN well layers and GaN barrier layers.

9. The semiconductor light emitting diode of claim 8, wherein at least one barrier layer is of Si-doped GaN and the barrier layer that is finally layered is of undoped GaN.

10. The semiconductor light emitting diode of claim 1, wherein said ohmic electrode is an alloy or a multilayer film including at least one type selected from the group consisting of Ni, Pd, Co, Fe, Ti, Cu, Rh, Au, Ru, W, Zr, Mo, Ta, Pt, Ag, and combinations, oxides or nitrides thereof.

11. The semiconductor light emitting diode of claim 10, wherein the semiconductor layers comprise a n-side semiconductor layer, a p-side semiconductor layer and an active layer interposed between the n-side semiconductor layer and p-side semiconductor layer.

12. The semiconductor light emitting diode of claim 11, wherein the sequence of the semiconductor layers is n-side semiconductor layer/active layer/p-side semiconductor layer or p-side semiconductor layer/active layer/n-side semiconductor layer.

13. The semiconductor light emitting diode of claim 12, wherein a pitch of the protruding portions is less than 50 micrometers.

14. The semiconductor light emitting diode of claim 13, wherein a pitch of the protruding portions is less than 10 micrometers.

15. The semiconductor light emitting diode of claim 14, wherein an edge or a corner of one of the protruding portions is rounded in a plan view.

16. The semiconductor light emitting diode of claim 15, wherein the shape of protruding portions, in a plan view, is circular.

17. The semiconductor light emitting diode of claim 14, wherein said active layer comprises InGaN well layers and GaN barrier layers.

18. The semiconductor light emitting diode of claim 17, wherein at least one barrier layer is of Si-doped GaN and the barrier layer that is finally layered is of undoped GaN.

19. The semiconductor light emitting diode of claim 1, wherein said electrode is an alloy or a multilayer film including at least one type selected from the group consisting of Rh, Ir, Ag and Al.

20. The semiconductor light emitting diode of claim 19, wherein the electrode is reflective so that light generated in the light emitting region is emitted through the substrate.

21. The semiconductor light emitting diode of claim 20, wherein the semiconductor layers comprise a n-side semiconductor layer, a p-side semiconductor layer and an active layer interposed between the n-side semiconductor layer and p-side semiconductor layer.

22. The semiconductor light emitting diode of claim 21, wherein the sequence of the semiconductor layers is n-side semiconductor layer/active layer/p-side semiconductor layer or p-side semiconductor layer/active layer/n-side semiconductor layer.

23. The semiconductor light emitting diode of claim 22, wherein a pitch of the protruding portions is less than 50 micrometers.

24. The semiconductor light emitting diode of claim 23, wherein a pitch of the protruding portions is less than 10 micrometers.

25. The semiconductor light emitting diode of claim 24, wherein an edge or a corner of one of the protruding portions is rounded in a plan view.

26. The semiconductor light emitting diode of claim 24, wherein the shape of the protruding portions, in a plan view, is circular.

27. The semiconductor light emitting diode of claim 26, wherein said active layer comprises InGaN well layers and GaN barrier layers.

28. The semiconductor light emitting diode of claim 27, wherein at least one barrier layer is of Si-doped GaN and the barrier layer that is finally layered is of undoped GaN.

29. The semiconductor light emitting diode of claim 1, wherein the areas surrounding said protruding portions are filled with a buffer layer and a GaN layer.

30. The semiconductor light emitting diode of claim 1, wherein the plurality of semiconductor layers comprises nitride semiconductor layers.

31. The semiconductor light emitting diode of claim 1, wherein the protruding portions are formed so as to define a triangle as the repeating pattern in the plan view of the substrate.

32. The semiconductor light emitting diode of claim 1, wherein the protruding portions are formed so as to define a hexagon as the repeating pattern in the plan view of the substrate.

33. The semiconductor light emitting diode of claim 32, wherein the hexagon is a regular hexagon.

34. The semiconductor light emitting diode of claim 1, wherein areas surrounding the protruding portions are filled in with at least one of the semiconductor layers so as to prevent cavities from being formed around the protruding portions.

35. The semiconductor light emitting diode of claim 1, wherein the protruding portions are formed so as to prevent crystal defects from occurring in the plurality of semiconductor layers.

43. The semiconductor light emitting diode of claim 31, wherein the triangle is a regular triangle.

36. A semiconductor light emitting diode comprising a substrate, an ohmic electrode and a plurality of semiconductor layers and configured so that light generated in said plurality of semiconductor layers is emitted from said ohmic electrode or from said substrate,

wherein said substrate comprises sapphire,

protruding portions are formed in a repeating pattern within substantially an entire surface of the substrate so as to define a polygon as the repeating pattern in plan view of the substrate while the rest of the surface is substantially flat,

cross sections of the protruding portions taken along planes orthogonal to the surface of the substrate are convex in shape, and

said protruding portions are formed so as to scatter or to diffract light generated in said plurality of light semiconductor layers.

37. The semiconductor light emitting diode of claim 36, wherein the areas surrounding said protruding portions are filled with a buffer layer and a GaN layer.

38. The semiconductor light emitting diode of claim 36, wherein the plurality of semiconductor layers comprises nitride semiconductor layers.

39. The semiconductor light emitting diode of claim 36, wherein the protruding portions are formed so as to define a triangle as the repeating pattern in the plan view of the substrate.

40. The semiconductor light emitting diode of claim 39, wherein the triangle is a regular triangle.

41. The semiconductor light emitting diode of claim 36, wherein the protruding portions are formed so as to define a hexagon as the repeating pattern in the plan view of the substrate.

42. The semiconductor light emitting diode of claim 41, wherein the hexagon is a regular hexagon.

44. The semiconductor light emitting diode of claim 36, wherein areas surrounding the protruding portions are filled in with at least one of the semiconductor layers so as to prevent cavities from being formed around the protruding portions.

45. The semiconductor light emitting diode of claim 36, wherein the protruding portions are formed so as to prevent crystal defects from occurring in the plurality of semiconductor layers.

46. The semiconductor light emitting diode of claim 36, wherein a pitch of the protruding portions is less than 10 micrometers.

47. The semiconductor light emitting diode of claim 36, wherein the semiconductor layers each comprise a GaN-based semiconductor, and the protruding portions do not have a side surface that is parallel to a plane that includes an A axis of the semiconductor layers.