USRE42074EExpiredUtility

Manufacturing method of light emitting device

Assignee: SANYO ELECTRIC COPriority: Apr 26, 1996Filed: Dec 18, 2002Granted: Jan 25, 2011

Est. expiryApr 26, 2016(expired)· nominal 20-yr term from priority

Inventors:Tatsuya Kunisato Takashi Kano Yasuhiro Ueda Yasuhiko Matsushita Katsumi Yagi

H01S 5/0213H01S 2301/173H01S 5/2231H01S 5/221H01S 5/32341H01S 2304/04H10H 20/01335H10H 20/81H10H 20/825H01S 5/321H01S 5/2202

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Claims

Abstract

A method of manufacturing a light emitting device, including the steps of: forming an active layer composed of a compound semiconductor containing indium by a vapor phase growth method; and forming a cap layer composed of a compound semiconductor on said active layer by a vapor phase growth method at a growth temperature approximately equal to or lower than a growth temperature for said active layer.

Claims

exact text as granted — not AI-modified

1. A method of manufacturing a light emitting device, comprising the steps of:
forming an active layer composed of a nitride system semiconductor by a vapor phase growth method; forming a cap layer composed of a nitride system semiconductor on said active layer by a vapor phase growth method at a growth temperature approximately equal to or lower than a growth temperature for said active layer; and forming a cladding layer composed of a nitride system semiconductor of one conductivity type on said cap layer by a vapor phase growth method; wherein said cap layer has a lower impurity concentration than said cladding layer.

2. The method of manufacturing a light emitting device according to claim 1 , wherein
said active layer is composed of a III-V group nitride system semiconductor, said cap layer is composed of a III-V group nitride system semiconductor, and said cladding layer is composed of a III-V group nitride system semiconductor.

3. The method of manufacturing a light emitting device according to claim 2 , wherein said step of forming a cladding layer includes forming said cladding layer at a growth temperature higher than the temperature allowing crystal growth of said active layer.

4. The method of manufacturing a light emitting device according to claim 3 , wherein
said cap layer is composed of Al u Ga 1−u N, said cladding layer is composed of Al z Ga 1−z N of one conductivity type, and the Al composition ratio u of said cap layer is smaller than the Al composition ratio z of said cladding layer.

5. The method of manufacturing a light emitting device according to claim 4 , wherein the Al composition ratio u of said cap layer is approximately equal to or smaller than 0.1.

6. The method of manufacturing a light emitting device according to claim 1 , wherein said cap layer is an undoped layer.

7. The method of manufacturing a light emitting device according to claim 1 , wherein said cap layer has a thickness of approximately not smaller than 200 Å nor larger than 400 Å.

8. The method of manufacturing a light emitting device according to claim 1 , wherein the step of forming said cap layer includes forming said cap layer at a growth temperature of not lower than 700° C. nor higher than 950° C.

9. The method of manufacturing a light emitting device according to claim 1 , wherein said step of forming said cap layer includes forming said cap layer at a growth temperature approximately equal to the growth temperature for said active layer.

10. The method of manufacturing a light emitting device according to claim 1 , wherein said active layer is composed of InGaN.

11. The method of manufacturing a light emitting device according to claim 1 , wherein said active layer has a quantum well structure including an InGaN quantum well layer and a GaN quantum barrier layer, and
the step of forming said active layer includes forming said GaN quantum barrier layer at a growth temperature of not lower than 700° C. nor higher than 950° C.

12. A method of manufacturing a light emitting device, comprising, in the following order, the steps of:
forming a buffer layer composed of a nitride based compound semiconductor on a substrate; forming an underlayer composed of a nitride based compound semiconductor; forming a first cladding layer composed of a nitride based compound semiconductor of a first conductivity type; forming an active layer composed of a nitride based compound semiconductor containing indium; forming a cap layer composed of AlGaN; forming a second cladding layer composed of a nitride based compound semiconductor of a second conductivity type at a growth temperature higher than that of said active layer, wherein said step of forming the active layer includes forming a quantum well structure including a quantum well layer and quantum barrier layer.

13. The method according to claim 12 , further comprising the step of forming a contact layer of the first conductivity type on said underlayer.

14. The method according to claim 13 , wherein said step of forming the contact layer of the first conductivity type includes forming said contact layer of the first conductivity type at a growth temperature of not lower than 1000 ° C. nor higher than 1200 ° C.

15. The method according to claim 12 , further comprising the step of forming a contact layer of the second conductivity type on said second cladding layer.

16. The method according to claim 15 , wherein said step of forming the contact layer of the second conductivity type includes forming a contact layer of the second conductivity type composed of GaN.

17. The method according to claim 12 , wherein said step of forming said quantum well structure includes forming a quantum well layer composed of In s Ga 1−s N wherein 1 &gt;s&gt; 0 .

18. The method according to claim 12 , wherein said step of forming the quantum well structure includes forming a quantum well layer composed of In s Ga 1−s N wherein 1 &gt;s&gt; 0 , and a quantum barrier layer composed of In r Ga 1−r N wherein 1 &gt;s&gt;r≧ 0 .

19. The method according to claim 12 , wherein said step of forming the cap layer includes forming a cap layer having an Al composition ratio of at most 0 . 1 .

20. A method of manufacturing a light emitting device, comprising, in the following order, the steps of:
forming a buffer layer composed of a nitride based compound semiconductor on a substrate; forming an underlayer composed of a nitride based compound semiconductor; forming a first cladding layer composed of a nitride based compound semiconductor of a first conductivity type; forming an active layer composed of a nitride based compound semiconductor containing indium; forming a cap layer composed of AlGaN; forming a second cladding layer composed of a nitride based compound semiconductor of a second conductivity type at a growth temperature higher than that of said active layer, wherein said step of forming the cap layer includes forming a cap layer having a bandgap between those of said active layer and said second cladding layer.

21. A method of manufacturing a light emitting device, comprising, in the following order, the steps of:
forming a buffer layer composed of a nitride based compound semiconductor on a substrate; forming an underlayer composed of a nitride based compound semiconductor; forming a first cladding layer composed of a nitride based compound semiconductor of a first conductivity type; forming an active layer composed of a nitride based compound semiconductor containing indium; forming a cap layer composed of AlGaN; forming a second cladding layer composed of a nitride based compound semiconductor of a second conductivity type at a growth temperature higher than that of said active layer, wherein said step of forming the cap layer includes forming a cap layer having an impurity concentration lower than that of said second cladding layer.

22. The method according to claim 12 , wherein said step of forming the cap layer includes forming an undoped cap layer.

23. The method according to claim 12 , wherein said step of forming the cap layer includes forming a cap layer having a thickness of not smaller than 200 Å nor larger than 400 Å.

24. The method according to claim 12 , wherein said step of forming the second cladding layer includes forming a second cladding layer composed of AlGaN.

25. The method according to claim 24 , wherein said step of forming the cap layer includes forming a cap layer having an Al composition ratio smaller than that of said second cladding layer.

26. The method according to claim 12 , wherein said step of forming the cap layer includes forming as said cap layer a layer suppressing elimination of the indium from said active layer.

27. The method according to claim 12 , wherein said step of forming the underlayer includes forming an underlayer composed of Al y Ga 1−y N, and the Al composition ratio y of said underlayer is at least 0 and smaller than 1 .

28. The method according to claim 12 , wherein said step of forming the buffer layer includes forming a buffer layer composed of Al x Ga 1−x N, and the Al composition ratio x of said buffer layer is larger than 0 and at most 1 .

29. The method according to claim 28 , wherein said step of forming the buffer layer includes forming a buffer layer having an Al composition ratio x of not smaller than 0 . 4 nor larger than 0 . 6 .

30. The method according to claim 12 , wherein said step of forming the active layer includes forming an active layer composed of InGaN.

31. The method according to claim 12 , wherein said step of forming the active layer includes forming said active layer at a growth temperature of not lower than 700 ° C. nor higher than 950 ° C.

32. The method according to claim 12 , wherein said step of forming the second cladding layer includes forming said second cladding layer at a growth temperature of not lower than 1000 ° C. nor higher than 1200 ° C.

33. The method according to claim 12 , wherein said step of forming the first cladding layer includes forming a first cladding layer composed of AlGaN.

34. The method according to claim 12 , wherein said step of forming the cap layer includes forming said cap layer at a growth temperature substantially equal to or lower than that of said active layer.

35. The method according to claim 12 , wherein said step of forming the cap layer includes forming said cap layer at a growth temperature of not lower than 700 ° C. nor higher than 950 ° C.

36. A method of manufacturing a light emitting device, comprising, in the following order, the steps of:
forming a buffer layer composed of a nitride based compound semiconductor on a substrate; forming an underlayer composed of a nitride based compound semiconductor; forming a first cladding layer composed of a nitride based compound semiconductor of a first conductivity type; forming an active layer composed of a nitride based compound semiconductor containing indium; forming a cap layer composed of AlGaN; forming a second cladding layer composed of a nitride based compound semiconductor of a second conductivity type at a growth temperature higher than that of said active layer, wherein said step of forming the underlayer includes forming an undoped underlayer.

37. The method according to claim 12 , wherein said step of forming the buffer layer includes forming a non- single crystalline buffer layer.

38. The method according to claim 12 , wherein said step of forming the underlayer includes forming a single crystalline underlayer.

39. The method according to claim 12 , wherein said step of forming the cap layer includes forming the cap layer containing Al.

40. The method according to claim 12 , wherein said step of forming the cap layer includes forming a cap layer having a band gap larger than that of said active layer.

41. A method of manufacturing a light emitting device, comprising, in the following order, the steps of:
forming a buffer layer composed of a nitride based compound semiconductor; forming an underlayer composed of a nitride based compound semiconductor; forming a contact layer composed of a first conductivity type; forming a first cladding layer composed of a nitride based compound semiconductor of the first conductivity type; forming an active layer having a quantum well structure including a quantum well layer and a quantum barrier layer and composed of a nitride based compound semiconductor containing indium; forming a cap layer composed of a nitride based compound semiconductor; forming a second cladding layer composed of a nitride based compound semiconductor of a second conductivity type at a growth temperature higher than that of said active layer.

42. The method according to claim 41 , wherein said step of forming the contact layer of the first conductivity type includes forming said contact layer of the first conductivity type at a growth temperature of not lower than 1000 ° C. nor higher than 1200 ° C.

43. The method according to claim 41 , further comprising the step of forming a contact layer of the second conductivity type on said second cladding layer.

44. The method according to claim 41 , wherein said step of forming the contact layer of the second conductivity type includes forming a contact layer of the second conductivity type composed of GaN.

45. The method according to claim 41 , wherein said step of forming the active layer includes forming a quantum well layer composed of In s Ga 1−s N wherein 1 &gt;s&gt; 0 .

46. The method according to claim 41 , wherein said step of forming the active layer includes forming a quantum well layer composed of In s Ga 1−s N wherein 1 &gt;s&gt; 0 , and a quantum barrier layer composed of In r Ga 1−r N wherein 1 &gt;s&gt;r≧ 0 .

47. The method according to claim 41 , wherein said step of forming the cap layer includes forming a cap layer having an Al composition ratio of at most 0 . 1 .

48. The method according to claim 41 , wherein said step of forming the cap layer includes forming a cap layer having a bandgap between those of said active layer and said second cladding layer.

49. The method according to claim 41 , wherein said step of forming the cap layer includes forming a cap layer having an impurity concentration lower than that of said second cladding layer.

50. The method according to claim 41 , wherein said step of forming the cap layer includes forming an undoped cap layer.

51. The method according to claim 41 , wherein said step of forming the cap layer includes forming a cap layer having a thickness of not smaller than 200 Å nor larger than 400 Å.

52. The method according to claim 41 , wherein said step of forming the second cladding layer includes forming a second cladding layer composed of AlGaN.

53. The method according to claim 52 , wherein said step of forming the cap layer includes forming a cap layer having an Al composition ratio smaller than that of said second cladding layer.

54. The method according to claim 41 , wherein said step of forming the cap layer includes forming as said cap layer a layer suppressing elimination of the indium from said active layer.

55. The method according to claim 41 , wherein said step of forming the underlayer includes forming an underlayer composed of Al y Ga 1−y N, and the Al composition ratio y of said underlayer is at least 0 and smaller than 1 .

56. The method according to claim 41 , wherein said step of forming the buffer layer includes forming a buffer layer composed of Al x Ga 1−x N, and the Al composition ratio x of said buffer layer is larger than 0 and at most 1 .

57. The method according to claim 108, wherein said step of forming the buffer layer includes forming a buffer layer having an Al composition ratio x of not smaller than 0 . 4 nor larger than 0 . 6 .

58. The method according to claim 41 , wherein said step of forming the active layer includes forming an active layer composed of InGaN.

59. The method according to claim 41 , wherein said step of forming the active layer includes forming said active layer at a growth temperature of not lower than 700 ° C. nor higher than 950 ° C.

60. The method according to claim 41 , wherein said step of forming the second cladding layer includes forming said second cladding layer at a growth temperature of not lower than 1000 ° C. nor higher than 1200 ° C.

61. The method according to claim 41 , wherein said step of forming the first cladding layer includes forming a first cladding layer composed of AlGaN.

62. The method according to claim 41 , wherein said step of forming the cap layer includes forming said cap layer at a growth temperature substantially equal to or lower than that of said active layer.

63. The method according to claim 41 , wherein said step of forming the cap layer includes forming said cap layer at a growth temperature not lower than 700 ° C. nor higher than 950 ° C.

64. The method according to claim 41 , wherein said step of forming the underlayer includes forming an undoped underlayer.

65. The method according to claim 41 , wherein said step of forming the buffer layer includes forming a non- single crystalline buffer layer.

66. The method according to claim 41 , wherein said step of forming the underlayer includes forming a single crystalline underlayer.

67. The method according to claim 41 , wherein said step of forming the cap layer includes forming a cap layer composed of AlGaN.

68. The method according to claim 67 , wherein said step of forming the cap layer includes forming the cap layer containing Al.

69. The method according to claim 41 , wherein said step of forming the cap layer includes forming a cap layer having a band gap larger than that of said active layer.

70. A method of manufacturing a light emitting device, comprising, in the following order, the steps of:
forming a buffer layer composed of a nitride based compound semiconductor on a substrate; forming an underlayer composed of a nitride based compound semiconductor; forming a contact layer composed of a first conductivity type; forming a first cladding layer composed of a nitride based compound semiconductor of the first conductivity type; forming an active layer having a quantum well structure including a quantum well layer and a quantum barrier layer and composed of a nitride based compound semiconductor containing indium; and forming a second cladding layer composed of a nitride based compound semiconductor of a second conductivity type at a growth temperature higher than that of said active layer.

71. The method according to claim 70 , wherein said step of forming the contact layer of the first conductivity type includes forming said contact layer of the first conductivity type at a growth temperature of not lower than 1000 ° C. nor higher than 1200 ° C.

72. The method according to claim 70 , further comprising the step of forming a contact layer of the second conductivity type on said second cladding layer.

73. The method according to claim 70 , wherein said step of forming the contact layer of the second conductivity type includes forming a contact layer of the second conductivity type composed of GaN.

74. The method according to claim 70 , wherein said step of forming the active layer includes forming a quantum well layer composed of In s Ga 1−s N wherein 1 &gt;s&gt; 0 .

75. The method according to claim 70 , wherein said step of forming the active layer includes forming a quantum well layer composed of In s Ga 1−s N wherein 1 &gt;s&gt; 0 , and a quantum barrier layer composed of In r Ga 1−r N wherein 1 &gt;s&gt;r≧ 0 .

76. The method according to claim 70 , wherein said step of forming the second cladding layer includes forming a second cladding layer composed of AlGaN.

77. The method according to claim 70 , wherein said step of forming the underlayer includes forming an underlayer composed of Al y Ga 1−y N, and the Al composition ratio y of said underlayer is at least 0 and smaller than 1 .

78. The method according to claim 70 , wherein said step of forming the buffer layer includes forming a buffer layer composed of Al x Ga 1−x N, and the Al composition ratio x of said buffer layer is larger than 0 and at most 1 .

79. The method according to claim 70 , wherein said step of forming the buffer layer includes forming a buffer layer having an Al composition ratio x of not smaller than 0 . 4 nor larger than 0 . 6 .

80. The method according to claim 70 , wherein said step of forming the active layer includes forming an active layer composed of InGaN.

81. The method according to claim 70 , wherein said step of forming the active layer includes forming said active layer at a growth temperature of not lower than 700 ° C. nor higher than 950 ° C.

82. The method according to claim 70 , wherein said step of forming the second cladding layer includes forming said second cladding layer at a growth temperature of not lower than 1000 ° C. nor higher than 1200 ° C.

83. The method according to claim 70 , wherein said step of forming the first cladding layer includes forming a first cladding layer composed of AlGaN.

84. The method according to claim 70 , wherein said step of forming the underlayer includes forming an undoped underlayer.

85. The method according to claim 70 , wherein said step of forming the buffer layer includes forming a non- single crystalline buffer layer.

86. The method according to claim 70 , wherein said step of forming the underlayer includes forming a single crystalline underlayer.

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