Light emitting device

• US 20050121688A1
• Filed: 12/02/2004
• Published: 06/09/2005
• Est. Priority Date: 12/03/2003
• Status: Active Grant

• Current Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Original Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Inventors: Akita, Katsushi, Sakurada, Takashi, Katayama, Koji, Nakamura, Takao, Kiyama, Makoto, Nagai, Youichi, Uematsu, Koji, Yoshimoto, Susumu, Ikeda, Ayako
• Granted Patent: US 7,190,004 B2
• Time in Patent Office: Days
• US Class Current: 257/99
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• 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 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• 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 2924/00014 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 2924/01004 Beryllium [Be]
• CPC Class Codes: H01L 2924/01012 Magnesium [Mg]
• CPC Class Codes: H01L 2924/01013 Aluminum [Al]
• CPC Class Codes: H01L 2924/01019 Potassium [K]
• CPC Class Codes: H01L 2924/01029 Copper [Cu]
• CPC Class Codes: H01L 2924/01046 Palladium [Pd]
• CPC Class Codes: H01L 2924/01078 Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 2924/19041 being a capacitor
• CPC Class Codes: H01L 33/0075 comprising nitride compounds
• CPC Class Codes: H01L 33/02 characterised by the semiconductor bodies
• 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 33/32 : containing nitrogen
• CPC Class Codes: H01L 33/38 : with a particular shape
• CPC Class Codes: H01L 33/58 : Optical field-shaping elements

Abstract

A light emitting device includes a nitride semiconductor substrate with a resistivity of 0.5 Ω·cm or less, an n-type nitride semiconductor layer and a p-type nitride semiconductor layer placed more distantly from the nitride semiconductor substrate than the n-type nitride semiconductor layer at a first main surface side of the nitride semiconductor substrate, and a light emitting layer placed between the n-type nitride semiconductor layer and the p-type nitride semiconductor layer, wherein one of the nitride semiconductor substrate and the p-type nitride semiconductor layer is mounted at the top side which emits light and the other is placed at the down side, and a single electrode is placed at the top side. Therefore, there is provided a light emitting device which has a simple configuration thereby making it easy to fabricate, can provide a high light emission efficiency for a long time period, and can be easily miniaturized.

Claims

1. A light emitting device comprising:

a nitride semiconductor substrate with a resistivity of 0.5 Ω

·

cm or less;

an n-type nitride semiconductor layer at a first main surface side of said nitride semiconductor substrate and a p-type nitride semiconductor layer placed more distantly from said nitride semiconductor substrate than said n-type nitride semiconductor layer at said first main surface side; and

a light emitting layer placed between said n-type nitride semiconductor layer and said p-type nitride semiconductor layer at said first main surface side, wherein

one of said nitride semiconductor substrate and said p-type nitride semiconductor layer is mounted at the top side which emits light and the other is placed at the down side, and a single electrode is placed at the top side.

2. The light emitting device according to claim 1, comprising first p-electrodes placed discretely over the surface of the p-type nitride semiconductor layer in contact with said p-type nitride semiconductor layer, a second p-electrode formed from Ag, Al or Rh which fills the gaps of the first p-electrodes and covers said p-type nitride semiconductor layer and said first p-electrodes.

3. The light emitting device according to claim 2, wherein the coverage ratio of said first p-electrodes relative to the surface of said p-type nitride semiconductor layer is in the range from 10 to 40%.

4. The light emitting device according to claim 1, wherein said light emitting device is sealed with resin and includes a fluorescent member at any portion of said light emitting device and any portion of said resin, and said fluorescent member generates fluorescence on receiving said light and white light is emitted from said resin to the outside.

5. The light emitting device according to claim 1, wherein said single electrode at the top side is placed at the center of said light emitting device, in a plane view of said respective layers.

6. The light emitting device according to claim 1, wherein said light emitting device is constructed such that a side-view type LED equipped with the light emitting device has a thickness of 0.5 mm or less.

7. The light emitting device according to claim 1, wherein said light emitting device is constructed such that a side-view type LED equipped with the light emitting device has a thickness of 0.4 mm or less.

8. The light emitting device according to claim 1 having an electrostatic withstand voltage of 3000 V or more.

9. The light emitting device according to claim 1, wherein there is not provided a protection circuit for protecting said light emitting device from transient voltages or electrostatic discharge, which would be otherwise applied between said nitride semiconductor substrate and said p-type nitride semiconductor layer.

10. The light emitting device according to claim 1, wherein there is not provided an electric power shunting circuit including Zener diodes for dealing with said transient voltages or electrostatic discharge.

11. The light emitting device according to claim 1 which causes light emission when a voltage of 4 V or less is applied thereto.

12. The light emitting device according to claim 1, wherein said nitride semiconductor substrate has a thickness in the range from 50 μ

m to 500 μ

m.

13. The light emitting device according to claim 1, wherein said electrode at the top side has an area ratio below 50% and the opening ratio or the transparent portion is higher than 50%.

14. The light emitting device according to claim 1, wherein at least one of the sides of said top-side surface has a length of 350 μ

m or less.

15. The light emitting device according to claim 1, wherein sides of said top-side surface which are opposed to each other both have a length of 400 μ

m or greater.

16. The light emitting device according to claim 1, wherein sides of said top-side surface which are opposed to each other both have a length of 1.6 mm or greater.

17. The light emitting device according to claim 1, wherein at least one of the sides of said top-side surface has a length of 250 μ

m or less.

18. The light emitting device according to claim 1 constructed to have a heat resistance of 30°

C./W or less.

19. The light emitting device according to claim 1, wherein the portion at which temperature rises most largely will have a temperature of 150°

C. or less under continuous light emitting conditions.

20. The light emitting device according to claim 1, wherein said n-type nitride semiconductor layer has a thickness of 3 μ

m or less.

21. The light emitting device according to claim 1, wherein said p-type nitride semiconductor layer is down-mounted, and the portion of the second main surface, which serves as the light emitting surface, of said nitride semiconductor substrate which has not been covered with said electrode has been subjected to a non-mirror-surface treatment.

22. The light emitting device according to claim 1, wherein said surfaces which have been subjected to the non-mirror-surface treatment are surfaces which were made to be non-mirror surfaces using potassium hydroxide (KOH) solution, sodium hydroxide (NaOH) solution, ammonia (NH₃) solution or other alkali solution.

23. The light emitting device according to claim 1, wherein said surfaces which have been subjected to the non-mirror-surface treatment are surfaces which were made to be non-mirror surfaces using at least one of sulfuric acid (H₂SO₄) solution, hydrochloric acid (HCl) solution, phosphoric acid (H₂PO₄) solution, hydrofluoric acid (HF) solution and other acid solution.

24. The light emitting device according to claim 1, wherein said surfaces which have been subjected to the non-mirror-surface treatment are surfaces which were made to be non-mirror surfaces using Reactive Ion Etching (RIE).

25. The light emitting device according to claim 1, wherein said electrode placed on the mounting side is formed from a material with a reflectivity of 0.5 or more.

26. The light emitting device according to claim 1, wherein a fluorescent plate is placed such that it covers the second main surface of said nitride semiconductor substrate.

27. The light emitting device according to claim 1, wherein a fluorescent plate is placed apart from said nitride semiconductor substrate such that it faces with the second main surface of said nitride semiconductor substrate.

28. The light emitting device according to claim 1, wherein the surface of said fluorescent plate to be faced with the second main surface of said nitride semiconductor substrate has been subjected to an asperities-forming process.

29. The light emitting device according to claim 1, wherein said nitride semiconductor substrate include at least one of impurities and defects which generate fluorescence.

30. A light emitting device comprising more than one said light emitting device according to claim 1, wherein these light emitting devices are connected in serial or parallel.

31. A light emitting device comprising said light emitting devices according to claim 1 and a power supply circuit for causing the light emitting devices to generate light, wherein in said power supply circuit, two or more parallel portions each including two or more said light emitting devices connected in parallel are connected in parallel.

58. The light emitting device according to claim 1, wherein sides of said top-side surface which are opposed to each other both have a length of 400 μ

m or greater.

90. The light emitting device according to claim 1, wherein sides of said top-side surface which are opposed to each other both have a length of 1.6 mm or greater.

104. A light emitting device comprising more than one said light emitting device according to claim 1, wherein these light emitting devices are connected in serial or parallel.

105. A light emitting device comprising said light emitting devices according to claim 1 and a power supply circuit for causing the light emitting devices to generate light, wherein in said power supply circuit, two or more parallel portions each including two or more said light emitting devices connected in parallel are connected in parallel.

120. The light emitting device according to claim 1, wherein at least one of the sides of said top-side surface has a length of 250 μ

m or less.

32. A light emitting device comprising a nitride semiconductor substrate GaN substrate with a dislocation density of 10⁸/cm² or less, an n-type Al_xGa₁₋

xN layer (x is within the range of 0 to

     1) which is an n-type nitride semiconductor layer at a first main surface side of said GaN substrate and a p-type Al_xGa<sub>1−

x</sub>N layer (x is within the range of 0 to

     1) placed more distantly from said GaN substrate than said n-type Al_xGa<sub>1−

x</sub>N layer at said first main surface side, and a light emitting layer placed between said n-type Al_xGa<sub>1−

x</sub>N layer and said p-type Al_xGa<sub>1−

x</sub>N layer at said first main surface side, wherein

an n-electrode is provided in contact with a second main surface of said GaN substrate which is the main surface at the opposite side from said first main surface, and a p-electrode is provided in contact with said p-type Al_xGa<sub>1−

x</sub>N layer, and

one of said n-electrode and said p-electrode is mounted at the top side which emits light and the other is mounted at the down side, and the electrode placed at the top side is constituted from a single electrode.

33. The light emitting device according to claim 32, wherein said GaN substrate is mounted at the top side and is n-typed with oxygen-doping, and said GaN substrate has an oxygen concentration in the range from 1E17 to 2E19 oxygen atoms/cm³ and a thickness of 100 μ

m to 600 μ

m.

34. The light emitting device according to claim 32, wherein said GaN substrate is mounted at the top side and is n-typed with oxygen-doping, and said GaN substrate has an oxygen concentration in the range from 2E18 to 5E18 oxygen atoms/cm³ and a thickness of 100 μ

m to 300 μ

m, the both side lengths of the rectangular-shaped surface of the light emitting surface at said second main surface are 0.5 mm or less.

35. The light emitting device according to claim 32, wherein said GaN substrate is mounted at the top side and is n-typed with oxygen-doping, and said GaN substrate has an oxygen concentration in the range from 3E18 to 5E18 oxygen atoms/cm³ and a thickness of 200 μ

m to 300 μ

m, and the both side lengths of the rectangular-shaped surface of the light emitting surface at said second main surface are 2 mm or less.

36. The light emitting device according to claim 32, wherein dislocation bundles are distributed over the first main surface of said GaN substrate with a density of 4E6/cm³ or less on average, wherein the dislocation bundles have been created by discretely concentrating dislocations which unavoidably generate during the formation of the GaN substrate into a string shape to distribute them along the substrate-thickwise direction in order to improve the crystallinity of the most region of said GaN substrate.

37. The light emitting device according to claim 32, wherein said dislocation bundles are distributed over said first main surface with a density of 4E2/cm³ or less on average, and the shorter side length of the light emitting surface at said second main surface is within the range from 200 μ

m to 400 μ

m.

38. The light emitting device according to claim 32, wherein between said GaN substrate and said n-type Al_xGa₁₋

xN layer (x is in the range from 0 to

     1), an n-type AlGaN buffer layer is placed in contact with said GaN substrate, an n-type GaN buffer layer is placed in contact with said n-type AlGaN buffer layer and said n-type Al_xGa<sub>1−

1</sub>N layer (x is in the range from 0 to

     1) is placed in contact with said n-type GaN buffer layer.

39. The light emitting device according to claim 38, wherein said GaN substrate includes a region with an off angle of 0.10°

or less and a region with an off angle of 1.0°

or more.

40. The light emitting device according to claim 32, wherein a p-type GaN buffer layer is placed in contact with said p-type Al_xGa₁₋

xN layer (x is in the range from 0 to

     1) at the down side thereof and a p-type InGaN contact layer is placed in contact with the p-type GaN buffer layer.

41. The light emitting device according to claim 40, wherein said p-type InGaN contact layer has a Mg concentration in the range of 1E18 atoms/cm³ to 1E21 atoms/cm³.

42. The light emitting device according to claim 40, wherein a p-electrode layer formed from Ag, Al or Rh is provided in contact with said p-type InGaN contact layer.

43. The light emitting device according to claim 32, wherein said GaN substrate includes plate-type crystal inversion regions extending continuously in the thickwise direction and in a single direction within the GaN substrate surface, said plate-type crystal inversion regions in the GaN substrate and plate-type crystal inversion regions propagated to said n-type and p-type nitride semiconductor layers formed on said GaN substrate are removed from said p-type nitride semiconductor layer side to the inside of said GaN substrate through said n-type nitride semiconductor layer, and, in contact with the portions of the p-type nitride semiconductor layer which are left after removing them, p-electrodes are provided for the respective portions of the p-type nitride semiconductor layer.

44. The light emitting device according to claim 43, wherein said plate-type crystal inversion regions are removed using KOH solution.

45. The light emitting device according to claim 32 comprising first p-electrodes placed discretely over the surface of the p-type nitride semiconductor layer in contact with said p-type nitride semiconductor layer, a second p-electrode formed from Ag, Al or Rh which fills the gaps of the first p-electrodes and covers said p-type nitride semiconductor layer and said first p-electrodes.

46. The light emitting device according to claim 45, wherein the coverage ratio of said first p-electrodes relative to the surface of said p-type nitride semiconductor layer is in the range from 10 to 40%.

47. The light emitting device according to claim 32, wherein said light emitting device is sealed with resin and includes a fluorescent member at any portion of said light emitting device and any portion of said resin, and said fluorescent member generates fluorescence on receiving said light and white light is emitted from said resin to the outside.

48. The light emitting device according to claim 32, wherein said single electrode at the top side is placed at the center of said light emitting device, in a plane view of said respective layers.

49. The light emitting device according to claim 32, wherein said light emitting device is constructed such that a side-view type LED equipped with the light emitting device has a thickness of 0.5 mm or less.

50. The light emitting device according to claim 32, wherein said light emitting device is constructed such that a side-view type LED equipped with the light emitting device has a thickness of 0.4 mm or less.

51. The light emitting device according to claim 32 having an electrostatic withstand voltage of 3000 V or more.

52. The light emitting device according to claim 32, wherein there is not provided a protection circuit for protecting said light emitting device from transient voltages or electrostatic discharge, which would be otherwise applied between said nitride semiconductor substrate and said p-type nitride semiconductor layer.

53. The light emitting device according to claim 32, wherein there is not provided an electric power shunting circuit including Zener diodes for dealing with said transient voltages or electrostatic discharge.

54. The light emitting device according to claim 32 which causes light emission when a voltage of 4 V or less is applied thereto.

55. The light emitting device according to claim 32, wherein said nitride semiconductor substrate has a thickness in the range from 50 μ

m to 500 μ

m.

56. The light emitting device according to claim 32, wherein said electrode at the top side has an area ratio below 50% and the opening ratio or the transparent portion is higher than 50%.

57. The light emitting device according to claim 32, wherein at least one of the sides of said top-side surface has a length of 350 μ

m or less.

59. The light emitting device according to claim 57, wherein sides of said top-side surface which are opposed to each other both have a length of 1.6 mm or greater.

60. The light emitting device according to claim 32, wherein at least one of the sides of said top-side surface has a length of 250 μ

m or less.

61. The light emitting device according to claim 32 constructed to have a heat resistance of 30°

C./W or less.

62. The light emitting device according to claim 32, wherein the portion at which temperature rises most largely will have a temperature of 150°

C. or less under continuous light emitting conditions.

63. The light emitting device according to claim 32, wherein said n-type nitride semiconductor layer has a thickness of 3 μ

m or less.

64. The light emitting device according to claim 32, wherein said p-type nitride semiconductor layer is down-mounted, and the portion of the second main surface, which serves as the light emitting surface, of said nitride semiconductor substrate which has not been covered with said electrode has been subjected to a non-mirror-surface treatment.

65. The light emitting device according to claim 64, wherein said surfaces which have been subjected to the non-mirror-surface treatment are surfaces which were made to be non-mirror surfaces using potassium hydroxide (KOH) solution, sodium hydroxide (NaOH) solution, ammonia (NH₃) solution or other alkali solution.

66. The light emitting device according to claim 64, wherein said surfaces which have been subjected to the non-mirror-surface treatment are surfaces which were made to be non-mirror surfaces using at least one of sulfuric acid (H₂SO₄) solution, hydrochloric acid (HCl) solution, phosphoric acid (H₂PO₄) solution, hydrofluoric acid (HF) solution and other acid solution.

67. The light emitting device according to claim 64, wherein said surfaces which have been subjected to the non-mirror-surface treatment are surfaces which were made to be non-mirror surfaces using reactive ion etching (RIE).

68. The light emitting device according to claim 32, wherein said surfaces which have been subjected to the non-mirror-surface treatment are surfaces which were made to be non-mirror surfaces using reactive ion etching (REI).

69. The light emitting device according to claim 32, wherein said electrode placed on the mounting side is formed from a material with a reflectivity of 0.5 or more.

70. The light emitting device according to claim 32, wherein a fluorescent plate is placed such that it covers the second main surface of said nitride semiconductor substrate.

71. The light emitting device according to claim 32, wherein a fluorescent plate is placed apart from said nitride semiconductor substrate such that it faces with the second main surface of said nitride semiconductor substrate.

72. The light emitting device according to claim 32, wherein said nitride semiconductor substrate include at least one of impurities and defects which generate fluorescence.

73. A light emitting device comprising more than one said light emitting device according to claim 32, wherein these light emitting devices are connected in serial or parallel.

74. A light emitting device comprising said light emitting devices according to claim 32 and a power supply circuit for causing the light emitting devices to generate light, wherein in said power supply circuit, two or more parallel portions each including two or more said light emitting devices connected in parallel are connected in parallel.

75. A light emitting device comprising a nitride semiconductor AlN substrate with a heat conductivity of 100 W/(m·

K) or more, an n-type Al_xGa<sub>1−

x</sub>N layer (x is within the range of 0 to

     1) which is an n-type nitride semiconductor layer at a first main surface side of said AlN substrate and a p-type Al_xGa<sub>1−

x</sub>N layer (x is within the range of 0 to

     1) placed more distantly from said AlN substrate than said n-type Al_xGa<sub>1−

x</sub>N layer at said first main surface side, and a light emitting layer placed between said n-type Al_xGa<sub>1−

x</sub>N layer and said p-type Al_xGa<sub>1−

x</sub>N layer at said first main surface side, wherein

an n-electrode is provided in contact with a second main surface of said AlN substrate which is the main surface at the opposite side from said first main surface, and a p-electrode is provided in contact with said p-type Al_xGa<sub>1−

x</sub>N layer,

one of said n-electrode and said p-electrode is mounted at the top side which emits light and the other is mounted at the down side, and the electrode placed at the top side is constituted from a single electrode.

76. The light emitting device according to claim 75, comprising first p-electrodes placed discretely over the surface of the p-type nitride semiconductor layer in contact with said p-type nitride semiconductor layer, a second p-electrode formed from Ag, Al or Rh which fills the gaps of the first p-electrodes and covers said p-type nitride semiconductor layer and said first p-electrodes.

77. The light emitting device according to claim 76, wherein the coverage ratio of said first p-electrodes relative to the surface of said p-type nitride semiconductor layer is in the range from 10 to 40%.

78. The light emitting device according to claim 75, wherein said light emitting device is sealed with resin and includes a fluorescent member at any portion of said light emitting device and any portion of said resin, and said fluorescent member generates fluorescence on receiving said light and white light is emitted from said resin to the outside.

79. The light emitting device according to claim 75, wherein said single electrode at the top side is placed at the center of said light emitting device, in a plane view of said respective layers.

80. The light emitting device according to claim 75, wherein said light emitting device is constructed such that a side-view type LED equipped with the light emitting device has a thickness of 0.5 mm or less.

81. The light emitting device according to claim 75, wherein said light emitting device is constructed such that a side-view type LED equipped with the light emitting device has a thickness of 0.4 mm or less.

82. The light emitting device according to claim 75 having an electrostatic withstand voltage of 3000 V or more.

83. The light emitting device according to claim 75, wherein there is not provided a protection circuit for protecting said light emitting device from transient voltages or electrostatic discharge, which would be otherwise applied between said nitride semiconductor substrate and said p-type nitride semiconductor layer.

84. The light emitting device according to claim 83, wherein there is not provided an electric power shunting circuit including Zener diodes for dealing with said transient voltages or electrostatic discharge.

85. The light emitting device according to claim 75 which causes light emission when a voltage of 4 V or less is applied thereto.

86. The light emitting device according to claim 75, wherein said nitride semiconductor substrate has a thickness in the range from 50 μ

m to 500 μ

m.

87. The light emitting device according to claim 75, wherein said electrode at the top side has an area ratio below 50% and the opening ratio or the transparent portion is higher than 50%.

88. The light emitting device according to claim 75, wherein at least one of the sides of said top-side surface has a length of 350 μ

m or less.

89. The light emitting device according to claim 88, wherein sides of said top-side surface which are opposed to each other both have a length of 400 μ

m or greater.

91. The light emitting device according to claim 75, wherein at least one of the sides of said top-side surface has a length of 250 μ

m or less.

92. The light emitting device according to claim 75 constructed to have a heat resistance of 30°

C./W or less.

93. The light emitting device according to claim 75, wherein the portion at which temperature rises most largely will have a temperature of 150°

C. or less under continuous light emitting conditions.

94. The light emitting device according to claim 75, wherein said n-type nitride semiconductor layer has a thickness of 3 μ

m or less.

95. The light emitting device according to claim 75, wherein said p-type nitride semiconductor layer is down-mounted, and the portion of the second main surface, which serves as the light emitting surface, of said nitride semiconductor substrate which has not been covered with said electrode has been subjected to a non-mirror-surface treatment.

96. The light emitting device according to claim 95, wherein said surfaces which have been subjected to the non-mirror-surface treatment are surfaces which were made to be non-mirror surfaces using potassium hydroxide (KOH) solution, sodium hydroxide (NaOH) solution, ammonia (NH₃) solution or other alkali solution.

97. The light emitting device according to claim 95, wherein said surfaces which have been subjected to the non-mirror-surface treatment are surfaces which were made to be non-mirror surfaces using at least one of sulfuric acid (H₂SO₄) solution, hydrochloric acid (HCl) solution, phosphoric acid (H₂PO₄) solution, hydrofluoric acid (HF) solution and other acid solution.

98. The light emitting device according to claim 96, wherein said surfaces which have been subjected to the non-mirror-surface treatment are surfaces which were made to be non-mirror surfaces using reactive ion etching (RIE).

99. The light emitting device according to claim 75, wherein said electrode placed on the mounting side is formed from a material with a reflectivity of 0.5 or more.

100. The light emitting device according to claim 75, wherein a fluorescent plate is placed such that it covers the second main surface of said nitride semiconductor substrate.

101. The light emitting device according to claim 75, wherein a fluorescent plate is placed apart from said nitride semiconductor substrate such that it faces with the second main surface of said nitride semiconductor substrate.

102. The light emitting device according to claim 75, wherein the surface of said fluorescent plate to be faced with the second main surface of said nitride semiconductor substrate has been subjected to an asperities-forming process.

103. The light emitting device according to claim 75, wherein said nitride semiconductor substrate include at least one of impurities and defects which generate fluorescence.

106. A light emitting device comprising a nitride semiconductor substrate with a resistivity of 0.5 Ω

·

cm or less, an n-type nitride semiconductor layer at a first main surface side of said nitride semiconductor substrate and a p-type nitride semiconductor layer placed more distantly from said nitride semiconductor substrate than said n-type nitride semiconductor layer at said first main surface side, and a light emitting layer placed between said n-type nitride semiconductor layer and said p-type nitride semiconductor layer at said first main surface side, wherein

said nitride semiconductor substrate is mounted at the down side and said p-type nitride semiconductor layer is mounted at the top side which emits light.

107. The light emitting device according to claim 106, wherein said light emitting device is sealed with resin and includes a fluorescent member at any portion of said light emitting device and any portion of said resin, and said fluorescent member generates fluorescence on receiving said light and white light is emitted from said resin to the outside.

108. The light emitting device according to claim 106, wherein said single electrode at the top side is placed at the center of said light emitting device, in a plane view of said respective layers.

109. The light emitting device according to claim 106, wherein said light emitting device is constructed such that a side-view type LED equipped with the light emitting device has a thickness of 0.5 mm or less.

110. The light emitting device according to claim 106, wherein said light emitting device is constructed such that a side-view type LED equipped with the light emitting device has a thickness of 0.4 mm or less.

111. The light emitting device according to claim 106 having an electrostatic withstand voltage of 3000 V or more.

112. The light emitting device according to claim 106, wherein there is not provided a protection circuit for protecting said light emitting device from transient voltages or electrostatic discharge, which would be otherwise applied between said nitride semiconductor substrate and said p-type nitride semiconductor layer.

113. The light emitting device according to claim 112, wherein there is not provided an electric power shunting circuit including Zener diodes for dealing with said transient voltages or electrostatic discharge.

114. The light emitting device according to claim 106 which causes light emission when a voltage of 4 V or less is applied thereto.

115. The light emitting device according to claim 106, wherein said nitride semiconductor substrate has a thickness in the range from 50 μ

m to 500 μ

m.

116. The light emitting device according to claim 106, wherein said electrode at the top side has an area ratio below 50% and the opening ratio or the transparent portion is higher than 50%.

117. The light emitting device according to claim 106, wherein at least one of the sides of said top-side surface has a length of 350 μ

m or less.

118. The light emitting device according to claim 117, wherein sides of said top-side surface which are opposed to each other both have a length of 400 μ

m or greater.

119. The light emitting device according to claim 117, wherein sides of said top-side surface which are opposed to each other both have a length of 1.6 mm or greater.

121. The light emitting device according to claim 106 constructed to have a heat resistance of 30°

C./W or less.

122. The light emitting device according to claim 106, wherein the portion at which temperature rises most largely will have a temperature of 150°

C. or less under continuous light emitting conditions.

123. The light emitting device according to claim 106, wherein said n-type nitride semiconductor layer has a thickness of 3 μ

m or less.

124. The light emitting device according to claim 106, wherein said p-type nitride semiconductor layer is down-mounted, and the portion of the second main surface, which serves as the light emitting surface, of said nitride semiconductor substrate which has not been covered with said electrode has been subjected to a non-mirror-surface treatment.

125. The light emitting device according to claim 124, wherein said surfaces which have been subjected to the non-mirror-surface treatment are surfaces which were made to be non-mirror surfaces using potassium hydroxide (KOH) solution, sodium hydroxide (NaOH) solution, ammonia (NH₃) solution or other alkali solution.

126. The light emitting device according to claim 124, wherein said surfaces which have been subjected to the non-mirror-surface treatment are surfaces which were made to be non-mirror surfaces using at least one of sulfuric acid (H₂SO₄) solution, hydrochloric acid (HCl) solution, phosphoric acid (H₂PO₄) solution, hydrofluoric acid (HF) solution and other acid solution.

127. The light emitting device according to claim 124, wherein said surfaces which have been subjected to the non-mirror-surface treatment are surfaces which were made to be non-mirror surfaces using reactive ion etching (RIE).

128. The light emitting device according to claim 106, wherein said electrode placed on the mounting side is formed from a material with a reflectivity of 0.5 or more.

129. The light emitting device according to claim 106, wherein a fluorescent plate is placed such that it covers the second main surface of said nitride semiconductor substrate.

130. The light emitting device according to claim 106, wherein a fluorescent plate is placed apart from said nitride semiconductor substrate such that it faces with the second main surface of said nitride semiconductor substrate.

131. The light emitting device according to claim 106, wherein the surface of said fluorescent plate to be faced with the second main surface of said nitride semiconductor substrate has been subjected to an asperities-forming process.

132. The light emitting device according to claim 106, wherein said nitride semiconductor substrate include at least one of impurities and defects which generate fluorescence.

133. A light emitting device comprising more than one said light emitting device according to claim 106, wherein these light emitting devices are connected in serial or parallel.

134. A light emitting device comprising said light emitting devices according to claim 106 and a power supply circuit for causing the light emitting devices to generate light, wherein in said power supply circuit, two or more parallel portions each including two or more said light emitting devices connected in parallel are connected in parallel.

135. A light emitting device comprising a GaN substrate with a dislocation density of 10⁸/cm² or less, an n-type nitride semiconductor layer at a first main surface side of said GaN substrate and a p-type nitride semiconductor placed more distantly from said GaN substrate than said n-type nitride semiconductor at said first main surface side, and a light emitting layer placed between said n-type nitride semiconductor layer and said p-type nitride semiconductor layer at said first main surface side, wherein

said GaN substrate is mounted at the down side and said p-type nitride semiconductor layer is provided at the top side which emits light.

136. The light emitting device according to claim 135, wherein dislocation bundles are distributed over the first main surface of said GaN substrate with a density of 4E6/cm³ or less on average, wherein the dislocation bundles have been created by discretely concentrating dislocations which unavoidably generate during the formation of the GaN substrate into a string shape to distribute them along the substrate-thickwise direction in order to improve the crystallinity of the most region of said GaN substrate.

137. The light emitting device according to claim 136, wherein said dislocation bundles are distributed over said first main surface with a density of 4E2/cm³ or less on average, and the shorter side length of the light emitting surface at said second main surface is within the range from 200 μ

m to 400 μ

m.

138. The light emitting device according to claim 135, wherein between said GaN substrate and said n-type Al_xGa₁₋

xN layer (x is in the range from 0 to

     1), an n-type AlGaN buffer layer is placed in contact with said GaN substrate, an n-type GaN buffer layer is placed in contact with said n-type AlGaN buffer layer and said n-type Al_xGa<sub>1−

x</sub>N layer (x is in the range from 0 to

     1) is placed in contact with said n-type GaN buffer layer.

139. The light emitting device according to claim 138, wherein said GaN substrate includes a region with an off angle of 0.10°

or less and a region with an off angle of 1.0°

or more.

140. The light emitting device according to claim 135, wherein said light emitting device is sealed with resin and includes a fluorescent member at any portion of said light emitting device and any portion of said resin, and said fluorescent member generates fluorescence on receiving said light and white light is emitted from said resin to the outside.

141. The light emitting device according to claim 135, wherein said single electrode at the top side is placed at the center of said light emitting device, in a plane view of said respective layers.

142. The light emitting device according to claim 135, wherein said light emitting device is constructed such that a side-view type LED equipped with the light emitting device has a thickness of 0.5 mm or less.

143. The light emitting device according to claim 135, wherein said light emitting device is constructed such that a side-view type LED equipped with the light emitting device has a thickness of 0.4 mm or less.

144. The light emitting device according to claim 135 having an electrostatic withstand voltage of 3000 V or more.

145. The light emitting device according to claim 135, wherein there is not provided a protection circuit for protecting said light emitting device from transient voltages or electrostatic discharge, which would be otherwise applied between said nitride semiconductor substrate and said p-type nitride semiconductor layer.

146. The light emitting device according to claim 145, wherein there is not provided an electric power shunting circuit including Zener diodes for dealing with said transient voltages or electrostatic discharge.

147. The light emitting device according to claim 135 which causes light emission when a voltage of 4 V or less is applied thereto.

148. The light emitting device according to claim 135, wherein said nitride semiconductor substrate has a thickness in the range from 50 μ

m to 500 μ

m.

149. The light emitting device according to claim 135, wherein said electrode at the top side has an area ratio below 50% and the opening ratio or the transparent portion is higher than 50%.

150. The light emitting device according to claim 135, wherein at least one of the sides of said top-side surface has a length of 350 μ

m or less.

151. The light emitting device according to claim 150, wherein sides of said top-side surface which are opposed to each other both have a length of 400 μ

m or greater.

152. The light emitting device according to claim 150, wherein sides of said top-side surface which are opposed to each other both have a length of 1.6 mm or greater.

153. The light emitting device according to claim 135, wherein at least one of the sides of said top-side surface has a length of 250 μ

m or less.

154. The light emitting device according to claim 135 constructed to have a heat resistance of 30°

C./W or less.

155. The light emitting device according to claim 135, wherein the portion at which temperature rises most largely will have a temperature of 150°

C. or less under continuous light emitting conditions.

156. The light emitting device according to claim 135, wherein said n-type nitride semiconductor layer has a thickness of 3 μ

m or less.

157. The light emitting device according to claim 135, wherein said p-type nitride semiconductor layer is down-mounted, and the portion of the second main surface, which serves as the light emitting surface, of said nitride semiconductor substrate which has not been covered with said electrode has been subjected to a non-mirror-surface treatment.

158. The light emitting device according to claim 157, wherein said surfaces which have been subjected to the non-mirror-surface treatment are surfaces which were made to be non-mirror surfaces using potassium hydroxide (KOH) solution, sodium hydroxide (NaOH) solution, ammonia (NH₃) solution or other alkali solution.

159. The light emitting device according to claim 157, wherein said surfaces which have been subjected to the non-mirror-surface treatment are surfaces which were made to be non-mirror surfaces using at least one of sulfuric acid (H₂SO₄) solution, hydrochloric acid (HCl) solution, phosphoric acid (H₂PO₄) solution, hydrofluoric acid (HF) solution and other acid solution.

160. The light emitting device according to claim 157, wherein said surfaces which have been subjected to the non-mirror-surface treatment are surfaces which were made to be non-mirror surfaces using reactive ion etching (RIE).

161. The light emitting device according to claim 135, wherein said electrode placed on the mounting side is formed from a material with a reflectivity of 0.5 or more.

162. The light emitting device according to claim 135, wherein a fluorescent plate is placed such that it covers the second main surface of said nitride semiconductor substrate.

163. The light emitting device according to claim 135, wherein a fluorescent plate is placed apart from said nitride semiconductor substrate such that it faces with the second main surface of said nitride semiconductor substrate.

164. The light emitting device according to claim 135, wherein the surface of said fluorescent plate to be faced with the second main surface of said nitride semiconductor substrate has been subjected to an asperities-forming process.

165. The light emitting device according to claim 135, wherein said nitride semiconductor substrate include at least one of impurities and defects which generate fluorescence.

166. A light emitting device comprising more than one said light emitting device according to claim 135, wherein these light emitting devices are connected in serial or parallel.

167. A light emitting device comprising said light emitting devices according to claim 135 and a power supply circuit for causing the light emitting devices to generate light, wherein in said power supply circuit, two or more parallel portions each including two or more said light emitting devices connected in parallel are connected in parallel.