Side emitting illumination systems incorporating light emitting diodes

• US 20080170413A1
• Filed: 11/09/2007
• Published: 07/17/2008
• Est. Priority Date: 10/18/2005
• Status: Abandoned Application

• Current Assignee: Goldeneye, Inc.
• Original Assignee: Goldeneye, Inc.
• Inventors: Beeson, Karl W., Zimmerman, Scott M.
• Application Number:
  US11/983,441
• Publication Number:
  US 20080170413A1
• Time in Patent Office: Days
• US Class Current: 362/612
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133614 using photoluminescence, e.g. phosphors illuminated by UV or blue light
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/60 Reflective elements
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

The invention is a reflective light emitting diode. The light emitting diode reflects the externally incident light, thereby increasing the effective brightness of the light emitting diode. The light emitting diode reflects externally incident light with a reflectivity greater than 40 percent.

Claims

1-23. -23. (canceled)

24. A reflective light emitting diode comprising

a first doped semiconductor layer having an output surface;

a second doped semiconductor layer, said second doped semiconductor layer and said first doped semiconductor layer having opposite n and p conductivity types;

an active region interposed between said first doped semiconductor layer and said second doped semiconductor layer, said active region in electrical contact with said first doped semiconductor layer and said second doped semiconductor layer;

a first reflecting electrode in electrical contact with said first doped semiconductor layer;

a second reflecting electrode in electrical contact with said second doped semiconductor layer;

wherein said active region of said light emitting diode emits internally generated light through said output surface of said first doped semiconductor layer when a voltage is applied between said first reflecting electrode and said second reflecting electrode; and

wherein a portion of externally incident light incident on said light emitting diode is reflected by said first reflecting electrode and a portion of externally incident light incident on said light emitting diode is transmitted through said light emitting diode and reflected by said second reflecting electrode of said light emitting diode through said output surface, thereby increasing the effective brightness of said light emitting diode.

25. The reflective light emitting diode of claim 24 wherein said active region is a p-n homojunction, a p-n heterojunction, a double heterojunction, a single quantum well or a multiple quantum well.

26. The reflective light emitting diode of claim 24 wherein said first reflecting electrode and said second reflecting electrode are a reflecting metal or a partially transparent conducting oxide.

27. The reflective light emitting diode of claim 26 wherein said first reflecting electrode is a partially transparent conducting oxide and is partially reflective.

28. The reflective light emitting diode of claim 24 wherein the inner surface of said second reflecting electrode is adjacent to said second doped semiconductor layer;

said inner surface of said second reflecting electrode is reflective to said internally generated light emitted by said active region and to said externally incident light.

29. The reflective light emitting diode of claim 24 wherein the inner surface of said first reflecting electrode is adjacent to said first doped semiconductor layer;

said inner surface of said first reflecting electrode is reflective to said internally generated light emitted by said active region and to said externally incident light, wherein the outer surface of said first reflecting electrode is opposite said inner surface of said first reflecting electrode and said outer surface of said first reflecting electrode is reflective to said externally incident light.

30. The reflective light emitting diode of claim 24 wherein the inner surface of said second reflecting electrode is adjacent to said second doped semiconductor layer;

said inner surface of said second reflecting electrode is reflective to said internally generated light emitted by said active region and to said externally incident light; and

wherein the inner surface of said first reflecting electrode is adjacent to said first doped semiconductor layer;

said inner surface of said first reflecting electrode is reflective to said internally generated light emitted by said active region and to said externally incident light, wherein the outer surface of said first reflecting electrode is opposite said inner surface of said first reflecting electrode and said outer surface of said first reflecting electrode is reflective to said externally incident light.

31. The reflective light emitting diode of claim 24 wherein said first reflecting electrode only partially covers said first doped semiconductor layer, said output surface of said first doped semiconductor layer being formed from the portions of said first doped semiconductor layer not covered by said first reflecting electrode.

32. The reflective light emitting diode of claim 24 wherein said first reflecting electrode and said second reflecting electrode are formed from one or more metals or metal alloys of silver, aluminum, nickel, titanium, chromium, platinum, palladium, rhodium, rhenium, ruthenium and tungsten.

33. The reflective light emitting diode of claim 24 wherein said first reflecting electrode has a reflectivity greater than 80 percent in the emitting wavelength range of said internally generated light.

34. The reflective light emitting diode of claim 33 wherein said first reflecting electrode is aluminum or silver.

35. The reflective light emitting diode of claim 24 wherein said second reflecting electrode has a reflectivity greater than 98 percent in the emitting wavelength range of said internally generated light.

36. The reflective light emitting diode of claim 35 wherein said second reflecting electrode is silver.

37. The reflective light emitting diode of claim 24 wherein the absorption coefficient of said first doped semiconductor layer, said active region and said second doped semiconductor layer in the emitting wavelength range of said internally generated light is less than 50 cm⁻

1.

38. The reflective light emitting diode of claim 24 wherein a current spreading layer is positioned between said first reflecting electrode and said first doped semiconductor layer, said current spreading layer having the same conductivity type as said first doped semiconductor layer or wherein a current spreading layer is positioned between said second reflecting electrode and said second doped semiconductor layer, said current spreading layer having the same conductivity type as said second doped semiconductor layer;

and

wherein said current spreading layer will improve the uniformity of current injection across said active region when a voltage is applied between said first reflecting electrode and said second reflecting electrode.

39. The reflective light emitting diode of claim 24 wherein an electron blocking layer is positioned between said first doped semiconductor layer and said active region or wherein an electron blocking layer is positioned between said second doped semiconductor layer and said active region;

and

wherein said electron blocking layer will reduce the escape of electrons from said active region.

40. The reflective light emitting diode of claim 24 wherein said light emitting diode is a plurality of said light emitting diodes.

41. The reflective light emitting diode of claim 40 wherein said plurality of said light emitting diodes emit more than one color of light.

42. The reflective light emitting diode of claim 24 wherein said light emitting diode reflects said externally incident light with a reflectivity greater than 40 percent.

43. The reflective light emitting diode of claim 24 wherein said light emitting diode reflects said externally incident light with a reflectivity greater than 60 percent.

44. The reflective light emitting diode of claim 24 further comprising a wavelength conversion layer that converts a portion of said internally generated light of a first color into light of a second color, different than said first color.

45. The reflective light emitting diode of claim 44 wherein said wavelength conversion layer is disposed on said output surface of said light emitting diode.

46. A reflective light emitting diode comprising

a first doped semiconductor layer having an output surface;

a second doped semiconductor layer, said second doped semiconductor layer and said first doped semiconductor layer having opposite n and p conductivity types;

an active region interposed between said first doped semiconductor layer and said second doped semiconductor layer, said active region in electrical contact with said first doped semiconductor layer and said second doped semiconductor layer;

a first reflecting electrode in electrical contact with said first doped semiconductor layer;

wherein said first reflecting electrode only partially covers said first doped semiconductor layer, said output surface of said first doped semiconductor layer being formed from the portions of said first doped semiconductor layer not covered by said first reflecting electrode;

a second reflecting electrode in electrical contact with said second doped semiconductor layer;

wherein said active region of said light emitting diode emits internally generated light through said output surface of said first doped semiconductor layer when a voltage is applied between said first reflecting electrode and said second reflecting electrode;

wherein the inner surface of said first reflecting electrode is adjacent to said first doped semiconductor layer;

said inner surface of said first reflecting electrode is reflective to said internally generated light emitted by said active region and to said externally incident light, wherein the outer surface of said first reflecting electrode is opposite said inner surface of said first reflecting electrode and said outer surface of said first reflecting electrode is reflective to said externally incident light.

wherein the inner surface of said second reflecting electrode is adjacent to said second doped semiconductor layer;

said inner surface of said second reflecting electrode is reflective to said internally generated light emitted by said active region and to said externally incident light; and

wherein a portion of externally incident light incident on said light emitting diode is reflected by said first reflecting electrode and a portion of externally incident light incident on said light emitting diode is transmitted through said light emitting diode and reflected by said second reflecting electrode of said light emitting diode through said output surface, thereby increasing the effective brightness of said light emitting diode.