Manufacturing method of light emitting device
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.
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 >s> 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 >s> 0 , and a quantum barrier layer composed of In r Ga 1−r N wherein 1 >s>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 >s> 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 >s> 0 , and a quantum barrier layer composed of In r Ga 1−r N wherein 1 >s>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 >s> 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 >s> 0 , and a quantum barrier layer composed of In r Ga 1−r N wherein 1 >s>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.