Semiconductor light emitting device
View Patent ↗According to one embodiment, a semiconductor light emitting device includes an n-type semiconductor layer, a p-type semiconductor layer, a light emitting portion, a first layer, a second layer, and an intermediate layer. The semiconductor layers include nitride semiconductor. The light emitting portion is provided between the n-type semiconductor layer and the p-type semiconductor layer and includes a quantum well layer. The first layer is provided between the light emitting portion and the p-type semiconductor layer and includes Al X1 Ga 1-x1 N having first Al composition ratio x 1 . The second layer is provided between the first layer and the p-type semiconductor layer and includes Al x2 Ga 1-x2 N having second Al composition ratio x 2 higher than the first Al composition ratio x 1 . The intermediate layer is provided between the first layer and the light emitting portion and has a thickness not smaller than 3 nanometers and not larger than 8 nanometers and includes In z1 Ga 1-z1 N (0≦z 1 <1).
1. A semiconductor light emitting device, comprising:
an n-type semiconductor layer including a nitride semiconductor;
a p-type semiconductor layer including a nitride semiconductor;
a light emitting portion provided between the n-type semiconductor layer and the p-type semiconductor layer and including a quantum well layer;
a first layer provided between the light emitting portion and the p-type semiconductor layer, the first layer including Al x1 Ga 1-x1 N, where first Al composition ratio x 1 is an atomic ratio of Al among group III elements, the first layer being doped with Mg;
a second layer provided between the first layer and the p-type semiconductor layer, the second layer including Al x2 Ga 1-x2 N, where second Al composition ratio x 2 is an atomic ratio of Al among group III elements, the second Al composition ratio x 2 being higher than the first Al composition ratio x 1 ; and
an intermediate layer provided between the first layer and the light emitting portion, the intermediate layer having a thickness not smaller than 3 nanometers and not larger than 8 nanometers and including In z1 Ga 1-z1 N, where In composition ratio z 1 is an atomic ratio of In among group III elements, the In composition ratio z 1 being not lower than 0 and lower than 1.
2. The device according to claim 1 , wherein a concentration of a p-type impurity in the second layer is higher than a concentration of a p-type impurity in the first layer.
3. The device according to claim 1 , wherein an Al composition ratio increases from the first layer toward the second layer.
4. The device according to claim 1 , wherein the first Al composition ratio x 1 is not lower than 0.001 and not higher than 0.05.
5. The device according to claim 1 , wherein the first Al composition ratio x 1 is substantially 0.05 and a thickness of the first layer is substantially 5 nanometers.
6. The device according to claim 1 , wherein the second Al composition ratio x 2 is not lower than 0.1 and not higher than 0.2.
7. The device according to claim 1 , wherein the second Al composition ratio x 2 is substantially 0.20 and a thickness of the second layer is substantially 5 nanometers.
8. The device according to claim 1 , wherein the intermediate layer does not include Al.
9. The device according to claim 1 , wherein the intermediate layer is made of one of GaN and InGaN.
10. The device according to claim 1 , further comprising:
a third layer provided between the first layer and the second layer, the third layer including Al x3 Ga 1-x3 N, where third Al composition ratio x 3 is an atomic ratio of Al among group III elements, the third Al composition ratio x 3 being between the first Al composition ratio and the second Al composition ratio; and
a fourth layer provided between the third layer and the second layer, the fourth layer including Al x4 Ga 1-x4 N, where fourth Al composition ratio x 4 is an atomic ratio of Al among group III elements, the fourth Al composition ratio x 4 being between the third Al composition ratio x 3 and the second Al composition ratio x 2 .
11. The device according to claim 1 , further comprising a third layer provided between the first layer and the second layer, the third layer including Al x3 Ga 1-x3 N, where third Al composition ratio x 3 is an atomic ratio of Al among group III elements, the third Al composition ratio being between the first Al composition ratio x 1 and the second Al composition ratio x 2 ,
the third Al composition ratio x 3 in the third layer increases along a direction from the light emitting portion toward the p-type semiconductor layer.
12. The device according to claim 11 , wherein the third layer includes a plurality of layers.
13. The device according to claim 1 , wherein the light emitting portion includes a plurality of barrier layers and a plurality of well layers, the barrier layers and the well layers being alternately stacked along a direction from the n-type semiconductor layer toward the p-type semiconductor layer.
14. The device according to claim 13 , wherein one of the plurality of barrier layers is in contact with the n-type semiconductor layer.
15. The device according to claim 13 , wherein one of the plurality of well layers is in contact with the intermediate layer.
16. The device according to claim 1 , wherein the n-type semiconductor layer includes an n-type GaN layer and a n-type guide layer, the n-type guide layer being provided between the n-type GaN layer and the light emitting portion and being made of one of GaN including Si and InGaN including Si.
17. The device according to claim 1 , wherein the p-type semiconductor layer includes a p-type GaN contact layer and a p-type GaN layer provided between the p-type GaN contact layer and the second layer, a concentration of a p-type impurity included in the p-type GaN layer being lower than a concentration of a p-type impurity included in the p-type GaN contact layer.
18. The device according to claim 1 , further comprising:
a substrate made of sapphire and provided on a side of the n-type semiconductor layer opposite to the p-type semiconductor layer; and
a buffer layer provided between the substrate and the n-type semiconductor layer.
19. The device according to claim 1 , further comprising:
an n-side electrode provided in contact with an exposed part of the n-type semiconductor layer; and
a p-side electrode provided in contact with the p-type semiconductor layer.
20. The device according to claim 1 , wherein the concentration of Mg in the first layer is not less than 1×10 17 cm −3 and not more than 1×10 19 cm −3 .
21. A semiconductor light emitting device, comprising:
an n-type semiconductor layer including a nitride semiconductor;
a p-type semiconductor layer including a nitride semiconductor;
a light emitting portion provided between the n-type semiconductor layer and the p-type semiconductor layer and including a quantum well layer;
a first layer provided between the light emitting portion and the p-type semiconductor layer, the first layer including Al X1 Ga 1-x1 N, where first Al composition ratio x 1 is an atomic ratio of Al among group III elements;
a second layer provided between the first layer and the p-type semiconductor layer, the second layer including Al x2 Ga 1-x2 N, where second Al composition ratio x 2 is an atomic ratio of Al among group III elements, the second Al composition ratio x 2 being higher than the first Al composition ratio x 1 ;
a third layer provided between the first layer and the second layer, the third layer including Al x3 Ga 1-x3 N, where third Al composition ratio x 3 is an atomic ratio of Al among group III elements, the third Al composition being between the first Al composition ratio x 1 and the second Al composition ratio x 2 , and
an intermediate layer provided between the first layer and the light emitting portion, the intermediate layer having a thickness not smaller than 3 nanometers and not larger than 8 nanometers and including In z1 Ga 1-z1 N, where In composition ratio z 1 is an atomic ratio of In among group III elements, the In composition ratio z 1 being not lower than 0 and lower than 1.
22. The device according to claim 21 , wherein a concentration of a p-type impurity in the second layer is higher than a concentration of a p-type impurity in the first layer.
23. The device according to claim 21 , wherein an Al composition ratio increases from the first layer toward the second layer.
24. The device according to claim 21 , wherein the first Al composition ratio x 1 is not lower than 0.001 and not higher than 0.05.
25. The device according to claim 21 , wherein the first Al composition ratio x 1 is substantially 0.05 and a thickness of the first layer is substantially 5 nanometers.
26. The device according to claim 21 , wherein the second Al composition ratio x 2 is not lower than 0.1 and not higher than 0.2.
27. The device according to claim 21 , wherein the second Al composition ratio x 2 is substantially 0.20 and a thickness of the second layer is substantially 5 nanometers.
28. The device according to claim 21 , wherein the intermediate layer does not include Al.
29. The device according to claim 21 , wherein the intermediate layer is made of one of GaN and InGaN.
30. The device according to claim 21 , further comprising:
a third layer provided between the first layer and the second layer, the third layer including Al x3 Ga 1-x3 N, where third Al composition ratio x 3 is an atomic ratio of Al among group III elements, the third Al composition ratio x 3 being between the first Al composition ratio and the second Al composition ratio; and
a fourth layer provided between the third layer and the second layer, the fourth layer including Al x4 Ga 1-x4 N, where fourth Al composition ratio x 4 is an atomic ratio of Al among group III elements, the fourth Al composition ratio x 4 being between the third Al composition ratio x 3 and the second Al composition ratio x 2 .
31. The device according to claim 21 , further comprising a third layer provided between the first layer and the second layer, the third layer including Al x3 Ga 1-x3 N, where third Al composition ratio x 3 is an atomic ratio of Al among group III elements, the third Al composition ratio being between the first Al composition ratio x 1 and the second Al composition ratio x 2 ,
the third Al composition ratio x 3 in the third layer increases along a direction from the light emitting portion toward the p-type semiconductor layer.
32. The device according to claim 31 , wherein the third layer includes a plurality of layers.
33. The device according to claim 21 , wherein the light emitting portion includes a plurality of barrier layers and a plurality of well layers, the barrier layers and the well layers being alternately stacked along a direction from the n-type semiconductor layer toward the p-type semiconductor layer.
34. The device according to claim 33 , wherein one of the plurality of barrier layers is in contact with the n-type semiconductor layer.
35. The device according to claim 33 , wherein one of the plurality of well layers is in contact with the intermediate layer.
36. The device according to claim 21 , wherein the n-type semiconductor layer includes an n-type GaN layer and a n-type guide layer, the n-type guide layer being provided between the n-type GaN layer and the light emitting portion and being made of one of GaN including Si and InGaN including Si.
37. The device according to claim 21 , wherein the p-type semiconductor layer includes a p-type GaN contact layer and a p-type GaN layer provided between the p-type GaN contact layer and the second layer, a concentration of a p-type impurity included in the p-type GaN layer being lower than a concentration of a p-type impurity included in the p-type GaN contact layer.
38. The device according to claim 21 , further comprising:
a substrate made of sapphire and provided on a side of the n-type semiconductor layer opposite to the p-type semiconductor layer; and
a buffer layer provided between the substrate and the n-type semiconductor layer.
39. The device according to claim 31 , further comprising:
an n-side electrode provided in contact with an exposed part of the n-type semiconductor layer; and
a p-side electrode provided in contact with the p-type semiconductor layer.
40. A semiconductor light emitting device, comprising:
an n-type semiconductor layer including a nitride semiconductor;
a p-type semiconductor layer including a nitride semiconductor;
a light emitting portion provided between the n-type semiconductor layer and the p-type semiconductor layer and including a quantum well layer;
a first layer provided between the light emitting portion and the p-type semiconductor layer, the first layer including Al X1 Ga 1-x1 N, where first Al composition ratio x 1 is an atomic ratio of Al among group III elements;
a second layer provided between the first layer and the p-type semiconductor layer and in direct contact with the first layer, the second layer including Al x2 Ga 1-x2 N, where second Al composition ratio x 2 is an atomic ratio of Al among group III elements, the second Al composition ratio x 2 being higher than the first Al composition ratio x 1 ; and
an intermediate layer provided between the first layer and the light emitting portion, the intermediate layer having a thickness not smaller than 3 nanometers and not larger than 8 nanometers and including In z1 Ga 1-z1 N, where In composition ratio z 1 is an atomic ratio of In among group III elements, the In composition ratio z 1 being not lower than 0 and lower than 1.
41. The device according to claim 40 , wherein a concentration of a p-type impurity in the second layer is higher than a concentration of a p-type impurity in the first layer.
42. The device according to claim 40 , wherein an Al composition ratio increases from the first layer toward the second layer.
43. The device according to claim 40 , wherein the first Al composition ratio x 1 is not lower than 0.001 and not higher than 0.05.
44. The device according to claim 40 , wherein the first Al composition ratio x 1 is substantially 0.05 and a thickness of the first layer is substantially 5 nanometers.
45. The device according to claim 40 , wherein the second Al composition ratio x 2 is not lower than 0.1 and not higher than 0.2.
46. The device according to claim 40 , wherein the second Al composition ratio x 2 is substantially 0.20 and a thickness of the second layer is substantially 5 nanometers.
47. The device according to claim 40 , wherein the intermediate layer does not include Al.
48. The device according to claim 40 , wherein the intermediate layer is made of one of GaN and InGaN.
49. The device according to claim 40 , further comprising:
a third layer provided between the first layer and the second layer, the third layer including Al x3 Ga 1-x3 N, where third Al composition ratio x 3 is an atomic ratio of Al among group III elements, the third Al composition ratio x 3 being between the first Al composition ratio and the second Al composition ratio; and
a fourth layer provided between the third layer and the second layer, the fourth layer including Al x4 Ga 1-x4 N, where fourth Al composition ratio x 4 is an atomic ratio of Al among group III elements, the fourth Al composition ratio x 4 being between the third Al composition ratio x 3 and the second Al composition ratio x 2 .
50. The device according to claim 40 , further comprising a third layer provided between the first layer and the second layer, the third layer including Al x3 Ga 1-x3 N, where third Al composition ratio x 3 is an atomic ratio of Al among group III elements, the third Al composition ratio being between the first Al composition ratio x 1 and the second Al composition ratio x 2 ,
the third Al composition ratio x 3 in the third layer increases along a direction from the light emitting portion toward the p-type semiconductor layer.
51. The device according to claim 50 , wherein the third layer includes a plurality of layers.
52. The device according to claim 40 , wherein the light emitting portion includes a plurality of barrier layers and a plurality of well layers, the barrier layers and the well layers being alternately stacked along a direction from the n-type semiconductor layer toward the p-type semiconductor layer.
53. The device according to claim 52 , wherein one of the plurality of barrier layers is in contact with the n-type semiconductor layer.
54. The device according to claim 52 , wherein one of the plurality of well layers is in contact with the intermediate layer.
55. The device according to claim 40 , wherein the n-type semiconductor layer includes an n-type GaN layer and a n-type guide layer, the n-type guide layer being provided between the n-type GaN layer and the light emitting portion and being made of one of GaN including Si and InGaN including Si.
56. The device according to claim 40 , wherein the p-type semiconductor layer includes a p-type GaN contact layer and a p-type GaN layer provided between the p-type GaN contact layer and the second layer, a concentration of a p-type impurity included in the p-type GaN layer being lower than a concentration of a p-type impurity included in the p-type GaN contact layer.
57. The device according to claim 40 , further comprising:
a substrate made of sapphire and provided on a side of the n-type semiconductor layer opposite to the p-type semiconductor layer; and
a buffer layer provided between the substrate and the n-type semiconductor layer.
58. The device according to claim 40 , further comprising:
an n-side electrode provided in contact with an exposed part of the n-type semiconductor layer; and
a p-side electrode provided in contact with the p-type semiconductor layer.