Semiconductor light emitting device including a fluorescent material

• US 20020088985A1
• Filed: 10/23/2001
• Published: 07/11/2002
• Est. Priority Date: 09/01/1997
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Komoto, Satoshi, Konno, Kuniaki, Furukawa, Chisato, Sugawara, Hideto, Suzuki, Nobuhiro, Nitta, Koichi
• Granted Patent: US 6,661,030 B2
• Time in Patent Office: Days
• US Class Current: 257/99
• CPC Class Codes: F21Y 2101/00 Point-like light sources
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48257 connecting the wire to a die pad of the item
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 2224/49107 on the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2224/8592 Applying permanent coating, e.g. protective coating
• 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 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 33/40 Materials therefor
• CPC Class Codes: H01L 33/507 the elements being in intimate contact with parts other than the semiconductor body or integrated with parts other than the semiconductor body
• CPC Class Codes: H01L 33/508 having a non-uniform spatial arrangement or non-uniform concentration, e.g. patterned wavelength conversion layer, wavelength conversion layer with a concentration gradient of the wavelength conversion material

Abstract

A semiconductor light emitting element, semiconductor light emitting device or image display device includes a wavelength converter for converting a wavelength into another, optical reflector having a wavelength selectivity and a light absorber having a wavelength selectivity, which are disposed in a predetermined positional relation, to prevent external leakage of primary light and to extract secondary light made by wavelength-converting the primary light with a very high efficiency. By using a semiconductor light emitting element for ultraviolet emission, or by combining it with a fluorescent material or any other appropriate material having a wavelength converting function, various kinds of applications, such as illuminator, having a remarkably long-life light source can be made. The semiconductor light emitting element preferably has a emission wavelength near 330 nm, and preferably uses BGaN in its light emitting layer. These light emitting element and device are stable in emission wavelength and can be readily configured for highly efficient wavelength conversion of any wavelength in a wide wavelength range from the visible light band to the infrared band. They can be used in various kinds of devices and instruments requiring a light source to simplify their structures, decreasing their sizes and weights, stabilize their emission wavelengths and quantities of light and elongate their lives.

Claims

1. A semiconductor light emitting element comprising:

a light emitting layer for emitting primary light having a first wavelength; and

a fluorescent material to absorb said primary light emitted from said light emitting layer and to emit secondary light having a second wavelength different from said first wavelength.

2. The semiconductor light emitting element according to claim 1 further comprising:

a first semiconductor layer having a first conduction type; and

a second semiconductor layer having a second conduction type located on said first semiconductor layer,

wherein said light emitting layer is located between said first semiconductor layer and said second semiconductor layer.

3. The semiconductor light emitting element according to claim 2 wherein said fluorescent material is incorporated in any of said first electrode and said second electrode.

4. The semiconductor light emitting element according to claim 2 wherein said fluorescent material is incorporated in any of said first semiconductor layer, said light emitting layer and said second semiconductor layer.

5. The semiconductor light emitting element according to claim 2 wherein said fluorescent material is deposited on a surface of said light emitting element.

6. The semiconductor light emitting element according to claim 2 wherein said light emitting layer contains a gallium nitride compound semiconductor and said second wavelength is longer than said first wavelength.

7. The semiconductor light emitting element according to claim 6 wherein said light emitting layer contains a gallium nitride compound semiconductor including indium.

8. The semiconductor light emitting element according to claim 2 wherein said light emitting layer contains a material selected from the group consisting of ZnSe, ZnSSe, ZnS, BN and SiC and said second wavelength is longer than said first wavelength.

9. The semiconductor light emitting element according to claim 2 wherein said first wavelength is not longer than 380 nm.

10. A semiconductor light emitting device comprising:

packaging member; and

,

a semiconductor light emitting element mounted on said packaging member, said semiconductor light emitting element including a first semiconductor layer of a first conduction type, a light emitting layer located on said first semiconductor layer for emitting primary light having a first wavelength, a second semiconductor layer of a second conduction type and a fluorescent material to absorb said primary light emitted from said light emitting layer and to emit secondary light having a second wavelength different from said first wavelength.

11. The semiconductor light emitting device according to claim 10 wherein said packaging member is a selected one from the group consisting of lead frame, stem and substrate.

13. The semiconductor light emitting device according to claim 12 wherein said wavelength converter contains an adhesive medium dispersed with said fluorescent material.

14. The semiconductor light emitting device according to claim 12 wherein said wavelength converter contains a medium dispersed with said fluorescent material, said medium containing a selected one from the group consisting of an inorganic polymer, a rubber material, a farinaceous material and a protein as a main component.

15. The semiconductor light emitting device according to claim 12 wherein said wavelength converter includes a layer of a medium containing a selected one from the group consisting of an inorganic polymer, a rubber organic material, a farinaceous material and a protein/as a main component, and said wavelength converter includes a layer of said fluorescent material stacked on said layer of a medium.

16. The semiconductor light emitting device according to claim 12 wherein the refractivity of said wavelength converter is between the refractivity of a light emitting part of said light emitting element and the refractivity of an adjacent part through where said secondary light is emitted.

18. The semiconductor light emitting device according to claim 17 wherein said packaging member is a selected one from the group consisting of lead frame, stem and substrate.

20. The semiconductor light emitting device according to claim 19 wherein said packaging member is a selected one from the group consisting of lead frame, stem and substrate.

12. A semiconductor light emitting device comprising:

a packaging member;

a semiconductor light emitting element packaged on said packaging member to emit primary light having a first wavelength; and

a wavelength converter located on a surface of said light emitting element and including a fluorescent material to absorb said primary light emitted from said light emitting element and to emit secondary light having a second wavelength different from said first wavelength.

17. A semiconductor light emitting device comprising:

a packaging member;

a semiconductor light emitting element packaged on said packaging member to emit primary light having a first wavelength; and

a resin molded so that said light emitting element is covered,

wherein said resin contains a fluorescent material in its surface region to absorb said primary light emitted from said light emitting element and to emit secondary light having a second wavelength different from said first wavelength.

19. A semiconductor light emitting device comprising:

a packaging member;

a semiconductor light emitting element packaged on said packaging member to emit primary light having a first wavelength;

a resin molded so that said light emitting element is covered; and

a wavelength convertor stacked on said resin,

wherein said wavelength converter contains a fluorescent material to absorb said primary light emitted from said light emitting element and to emit secondary light having a second wavelength different from said first wavelength.

21. A semiconductor light emitting device comprising:

a packaging member;

a semiconductor light emitting element packaged on said packaging member to emit primary light having a first wavelength; and

a fluorescent material absorbing said primary light emitted from said light emitting element and emitting secondary light having a second wavelength different from said first wavelength.

22. The semiconductor light emitting device according to claim 21 further comprising a resin molded so that said light emitting element is covered, wherein said resin has a cavity in its inside, said light emitting element is placed in said cavity, and said fluorescent material is deposited on a inner wall of said cavity.

23. The semiconductor light emitting device according to claim 21 further comprising a first resin formed so that said light emitting element is covered and a second resin formed so that said first resin is covered, wherein said first resin contains said fluorescent material.

24. The semiconductor light emitting device according to claim 23 wherein said first resin is, a dipping resin and said second resin is a molded resin.

25. The semiconductor light emitting device according to claim 21 wherein said packaging member contains said fluorescent material.

26. The semiconductor light emitting device according to claim 21 further comprising an adhesive fixing said light emitting element to said packaging member, wherein said adhesive contains said fluorescent material.

27. The semiconductor light emitting device according to claim 21 further comprising a wavelength converter stacked on said packaging member, wherein said wavelength converter contains said fluorescent material.

28. The semiconductor light emitting device according to claim 21 further comprising a reflector reflecting a light and a wavelength convertor stacked on said reflector, wherein said wavelength converter contains said fluorescent material.

29. The semiconductor light emitting device according to claim 21 further comprising a film layer to receive said primary light emitted from said light emitting element, wherein said film layer contains said fluorescent material.

30. The semiconductor light emitting device according to claim 21 further comprising a cap located to cover said light emitting element and a wavelength converter located on the light extraction part of said cap, wherein said wavelength converter contains said fluorescent material.

31. The semiconductor light emit device according to claim 21 further comprising a lens to converge a light emitted from said light emitting element, wherein said lens contains said fluorescent material in its inside or on its surface.

32. The semiconductor light emitting element according to claim 21 wherein said light emitting element has a light emitting layer containing a gallium nitride compound semiconductor, and said second wavelength is longer than said first wavelength.

33. The semiconductor light emitting element according to claim 21 wherein said light emitting element has a light emitting layer made of a material selected from the group consisting of ZnSe, ZnSSe, ZnS, BN and SiC, and said second wavelength is longer than said first wavelength.

34. The semiconductor light emitting element according to claim 21 wherein said first wavelength is not longer than 380 nm.

35. The semiconductor light emitting element according to claim 21 wherein said secondary light is a visible light.

36. The semiconductor light emitting element according to claim 21 wherein said secondary light has at least three wavelength peaks each of which substantially corresponds to red, green and blue, respectively.

38. The method according to claim 37 wherein said medium contains a selected one from the group consisting of an inorganic polymer, a rubber material, a farinaceous material and a protein as a main component.

40. The method according to claim 39 wherein said medium contains a selected on from the group consisting of an inorganic polymer, a rubber material, a farinaceous material and a protein as a main component.

37. A method for making a semiconductor light emitting device, comprising the steps of:

mounting a semiconductor light emitting element on a packaging member;

coating an adhesive medium on said light emitting element;

scattering a fluorescent material on said medium; and

hardening said medium.

39. A method for making a semiconductor light emitting device, comprising the steps of:

mounting a semiconductor light emitting element on a packaging member;

coating an adhesive medium dispersed with a fluorescent material on said light emitting element; and

hardening said medium.

41. A semiconductor light emitting element comprising:

a light emitting layer for emitting primary light having a first wavelength;

a wavelength converter located in the light extraction side of said light emitting layer to absorb said primary light emitted from said light emitting layer and to emit secondary light having a second wavelength different from said first wavelength; and

a light absorber located in the light extraction side of said wavelength converter, and having a low absorptance to said secondary light emitted from said wavelength converter and a high absorptance to said primary light emitted from said light emitting layer.

42. The semiconductor light emitting element according to claim 41 herein said light emitting layer contains as its major component a material selected from the group consisting of gallium nitride compound semiconductors, ZnSe, ZnS, ZnSSe, SiC and BN, said first wavelength is not longer than 380 nm, said wavelength converter contains a fluorescent material, and said secondary light is a visible light.

43. A semiconductor light emitting element comprising:

a light emitting layer for emitting primary light having a first wavelength;

a wavelength converter located in the light extraction side of said light emitting layer to absorb said primary light emitted from said light emitting layer and to emit secondary light having a second wavelength different from said first wavelength; and

a first optical reflector located in the light extraction side of said wavelength converter, and having a low reflectance to said secondary light emitted from said wavelength converter and a high reflectance to said primary light emitted from said light emitting layer.

44. The semiconductor light emitting element according to claim 43 wherein said light emitting layer contains as its major component a material selected from the group consisting of gallium nitride compound semiconductors, ZnSe, ZnS, ZnSSe, SiC and BN, said first wavelength is not longer than 380 nm, said wavelength converter contains a fluorescent material, and said secondary light is a visible light.

45. The semiconductor light emitting element according to one of claim 43 further comprising a light absorber located in the light extraction side of said wavelength converter, and having a low absorptance to said secondary light emitted from said wavelength converter and a high absorptance to said primary light emitted from said light emitting layer.

46. The semiconductor emitting element according to claim 45 wherein said first optical reflector is located between said light emitting layer and said light absorber.

48. The semiconductor light emitting element according to claim 47 wherein said light emitting layer contains as its major component a material selected from the group consisting of gallium nitride compound semiconductors, ZnSe, ZnS, ZnSSe, SiC and BN, said first wavelength is not longer than 380 nm, said wavelength converter contains a fluorescent material, and said secondary light is a visible light.

49. The semiconductor light emitting element according to one of claim 47 further comprising a light absorber located in the light extraction side of said wavelength converter, and having a low absorptance to said secondary light emitted from said wavelength converter and a high absorptance to said primary light emitted from said light emitting layer.

50. The semiconductor light emitting element according to claim 47 further comprising a first optical reflector located in the light extraction side of said wavelength converter, and having a low reflectance to said secondary light emitted from said wavelength converter and a high reflectance to said primary light emitted from said light layer.

47. A semiconductor light emitting element comprising:

a light emitting layer for emitting primary light having a first wavelength;

a wavelength converter located in the light extraction side of said light emitting layer to absorb said primary light emitted from said light emitting layer and to emit secondary light having a second wavelength different from said first wavelength; and

a second optical reflector located on one side of said light emitting layer opposite from the light extraction side to reflect said primary light.

51. A semiconductor light emitting element comprising:

a light emitting layer for emitting primary light having a first wavelength;

a wavelength converter located in the light extraction side of said light emitting layer to absorb said primary light emitted from said light emitting layer and to emit secondary light having a second wavelength different from said first wavelength; and

a third optical reflector configured to enclose said light emitting layer except the light extraction part to reflect said primary light emitted from said light emitting layer.

52. The semiconductor light emitting element according to claim 51 wherein said light emitting layer contains as its major component a material selected from the group consisting of gallium nitride compound semiconductors, ZnSe, ZnS, ZnSSe, SiC and BN, said first wavelength is not longer than 380 nm, said wavelength converter contains a fluorescent material, and said secondary light is a visible light.

53. The semiconductor light emitting element according to one of claim 51 further comprising a light absorber located in the light extraction side of said wavelength converter, and having a low absorptance to said secondary light emitted from said wavelength converter and a high absorptance to said primary light emitted from said light emitting layer.

54. The semiconductor light emitting element according to claim 51 further comprising a first optical reflector located in the light extraction side of said wavelength converter, and having a low reflectance to said secondary light emitted from said wavelength converter and a high reflectance to said primary light emitted from said light emitting layer.

55. A semiconductor light emitting element comprising:

a light emitting layer for emitting primary light having a first wavelength;

a wavelength converter located in the light extraction side of said light emitting layer to absorb said primary light emitted from said light emitting layer and to emit secondary light having a second wavelength different from said first wavelength; and

a fourth optical reflector located between said light emitting layer and said wavelength converter, and having a low reflectance to said primary light and a high reflectance to said secondary light.

56. The semiconductor light emitting element according to claim 55 wherein said light emitting layer contains as its major component a material selected from the group consisting of gallium nitride compound semiconductors, ZnSe, ZnS, ZnSSe, SiC and BN, said first wavelength is not longer than 380 nm, said wavelength converter contains a fluorescent material, and said secondary light is a visible light.

57. The semiconductor light emitting element according to one of claim 55 further comprising a light absorber located in the light extraction side of said wavelength converter, and having a low absorptance to said secondary light emitted from said wavelength converter and a high absorptance to said primary light emitted from said light emitting layer.

58. The semiconductor light emitting element according to claim 55 further comprising a first optical reflector located in the light extraction side of said wavelength converter, and having a low reflectance to said secondary light emitted from said wavelength converter and a high reflectance to said primary light emitted from said light emitting layer.

60. The semiconductor light emitting device according to claim 59 wherein said light emitting element contains in its light emitting layer a material elected from the group consisting of gallium nitride compound semiconductors, ZnSe, ZnS, ZnSSe, SiC and BN, said first wavelength is not longer than 380 nm, said wavelength converter contains a fluorescent material, and said secondary light is a visible light.

59. A semiconductor light emitting device comprising:

a packaging member;

a semiconductor light emitting element packaged on said packaging member to emit primary light having a first wavelength;

a wavelength converter located in the light extraction side of said light emitting element to absorb said primary light emitted from said light emitting element and to emit secondary light having a second wavelength different from said first wavelength; and

a light absorber located in the light extraction side of said wavelength converter, and having a low absorptance to said secondary light emitted from said wavelength converter and a high absorptance to said primary light emitted from said light emitting element.

61. A semiconductor light emitting device comprising:

a packaging member;

a semiconductor light emitting element packaged on said packaging member to emit primary light having a first wavelength;

a wavelength converter located in the light extraction side of said light emitting element to absorb said primary light emitted from said light emitting element and to emit secondary light having a second wavelength different from said first wavelength; and

a first opt cal reflector located in the light extraction side of said wavelength converter, and having a low reflectance to said secondary light emitted from said wavelength converter and a high reflectance to said primary light emitted from said light emitting element.

62. The semiconductor light emitting device according to claim 61 wherein said light emitting element contains in its light emitting layer a material selected from the group consisting of gallium nitride compound semiconductors, ZnSe, ZnS, ZnSSe, SiC and BN, said first wavelength is not longer than 380 nm, said wavelength converter contains a fluorescent material, and said secondary light is a visible light.

63. The semiconductor light emitting device according to claim 61 further comprising a light absorber located in the light extraction side of said wavelength converter, and having a low absorptance to said secondary light emitted from said wavelength converter and a high absorptance to said primary light emitted from said light emitting element.

64. The semiconductor light emitting device according to claim 63 wherein said first optical reflector is located between said light emitting element and said light absorber.

65. A semiconductor light emitting device comprising:

a packaging member;

a semiconductor light emitting element packaged on said packaging member to emit primary light having a first wavelength;

a wavelength converter located in the light extraction side of said light emitting element to absorb said primary light emitted from said light emitting element and to emit secondary light having a second wavelength different from said first wavelength; and

a second optical reflector located on one side of said light emitting element opposite from the light extraction side to reflect said primary light.

66. The semiconductor light emitting device according to claim 65 wherein said light emitting element contains in its light emitting layer a material selected from the group consisting of gallium nitride compound semiconductors, ZnSe, ZnS, ZnSSe, SiC and BN, said first wavelength is not longer than 380 nm, said wavelength converter contains a fluorescent material, and said secondary light is a visible light.

67. The semiconductor light emitting device according to claim 65 further comprising a light absorber located in the light extraction side of said wavelength converter, and having a low absorptance to said secondary light emitted from said wavelength converter and a high absorptance td said primary light emitted from said light emitting element.

68. The semiconductor light emitting device according to claim 65 further comprising a first optical reflector located in the light extraction side of said wavelength converter, and having a low reflectance to said secondary light emitted from said wavelength converter and a high reflectance to said primary light emitted from said light emitting element.

70. The semiconductor light emitting device according to claim 69 wherein said light emitting element contains in its light emitting layer a material selected from the group consisting of gallium nitride compound semiconductors, ZnSe, ZnS, ZnSSe, SiC and BN, said first wavelength is not longer than 380 nm, said wavelength converter contains a fluorescent material, and said secondary light is a visible light.

71. The semiconductor light emitting device according to claim 69 further comprising a light absorber located in the light extraction side of said wavelength converter, and having a low absorptance to said secondary light emitted from said wavelength converter and a high absorptance to said primary light emitted from said light emitting element.

72. The semiconductor light emitting device according to claim 69 further comprising a first optical reflector located in the light extraction side of said wavelength converter, and having a low reflectance to said secondary light emitted from said wavelength converter and a high reflectance to said primary light emitted from said light emitting element.

69. A semiconductor light emitting device comprising:

a packaging member;

a semiconductor light emitting element packaged on said packaging member to emit primary light having a first wavelength;

a wavelength converter located in the light extraction side of said light emitting element to absorb said primary light emitted from said light emitting element and to emit secondary light having a second wavelength different from said first wavelength; and

a third optical reflector configured to enclose said light emitting element except the light extraction part to reflect said primary light emitted from said light emitting element.

73. A semiconductor light emitting device comprising:

a packaging member;

a semiconductor light emitting element packaged on said packaging member to emit primary light having a first wavelength;

a wavelength converter located in the light extraction side of said light emitting element to absorb said primary light emitted from said light emitting element and to emit secondary light having a second wavelength different from said first wavelength; and

a fourth optical reflector located between said light emitting element and said wavelength converter, and having a low reflectance to said primary light and a high reflectance to said secondary light.

74. The semiconductor light emitting device according to claim 73 wherein said light emitting element contains in its light emitting layer a material selected from the group consisting of gallium nitride compound semiconductors, ZnSe, ZnS, ZnSSe, SiC and BN, said first wavelength is not longer than 380 nm, said wavelength converter contains a fluorescent material, and said secondary light is a visible light.

75. The semiconductor light emitting device according to claim 73 further comprising a light absorber located in the light extraction side of said wavelength converter, and having a low absorptance to said secondary light emitted from said wavelength converter and a high absorptance to said primary light emitted from said light emitting element.

76. The semiconductor light emitting device according to claim 73 further comprising a first optical reflector located in the light extraction side of said wavelength converter, and having a low reflectance to said secondary light emitted from said wavelength converter and a high reflectance to said primary light emitted from said light emitting element.

77. An image display device comprising:

a semiconductor light emitting element for emitting primary light having a first wavelength;

a luminance adjuster for adjusting intensity of said primary light emitted from said semiconductor light emitting element;

a wavelength converter for absorbing said primary light adjusted in intensity by said luminance adjuster and for emitting secondary light having a second wavelength different from said first wavelength; and

a first optical reflector located in the light extraction side of said wavelength converter, and having a low reflectance to said secondary light emitted from said wavelength converter and a high reflectance to said primary light emitted from said light emitting element.

78. The image display device according to claims 77 further comprising a light absorber located on the light extraction side of said first optical reflector, and having a low absorptance to said secondary light passing through said first optical reflector and a high absorptance to said primary light passing through said first optical reflector.

79. The image display device according to claim 77 further comprising a fourth optical reflector located between said semiconductor light emitting element and said wavelength converter, and having a low reflectance to said primary light and a high reflectance to said secondary light.

80. The image display device according to claim 77 wherein said light emitting element contains in its light emitting layer a material selected from the group consisting of gallium nitride compound semiconductors, ZnSe, ZnS, ZnSSe, SiC and BN, said first wavelength is not longer than 380 nm, said wavelength converter contains a fluorescent material, and said secondary light is a visible light.

81. An image display device comprising:

a semiconductor light emitting element for emitting primary lighting a first wavelength;

a wavelength converter for absorbing said primary light emitted from said semiconductor light emitting element and for releasing secondary light having a second wavelength different from said first wavelength;

a first optical reflector located in the light extraction side of said wavelength converter, and having a low reflectance to said secondary light released from said wavelength converter and a high reflectance to said primary light emitted from said light emitting element; and

a luminance adjuster for adjusting intensity of said secondary light passing through said first optical reflector.

82. The image display device according to claims 81 further comprising a light absorber located on the light extraction side of said first optical reflector, and having a low absorptance to said secondary light passing through said first optical reflector and a high absorptance to said primary light passing through said first optical reflector.

83. The image display device according to claim 81 further comprising a fourth optical reflector located between said semiconductor light emitting element and said wavelength converter, and having a low reflectance to said primary light and a high reflectance to said secondary light.

84. The image display device according to claim 81 wherein said light emitting element contains in its light emitting layer a material selected from the group consisting of gallium nitride compound semiconductors ZnSe, ZnS, ZnSSe, SiC and BN, said first wavelength is not longer than 380 nm, said wavelength converter contains fluorescent material, and said secondary light is a visible light.