Group III nitride based light emitting diode structures with a quantum well and superlattice, group III nitride based quantum well structures and group III nitride based superlattice structures

• US 6,958,497 B2
• Filed: 05/07/2002
• Issued: 10/25/2005
• Est. Priority Date: 05/30/2001
• Status: Expired due to Term

• Current Assignee: CREE Led Incorporated (Smart Global Holdings Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Ibbetson, James, Bergmann, Michael John, Emerson, David Todd, Doverspike, Kathleen Marie, O'Loughlin, Michael John, Abare, Amber Christine, Nordby, Howard Dean Jr.
• Primary Examiner(s): CRANE, SARA W
• Application Number:
  US10/140,796
• Publication Number:
  US 20030006418A1
• Time in Patent Office: 1,267 Days
• Field of Search: 257/79, 257/103, 257/94, 257/96, 257/97
• US Class Current: 257/94
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: H01L 21/0237 Materials
• CPC Class Codes: H01L 21/02378 Silicon carbide
• CPC Class Codes: H01L 21/02458 Nitrides
• CPC Class Codes: H01L 21/02505 consisting of more than two layers
• CPC Class Codes: H01L 21/02507 Alternating layers, e.g. superlattice
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/32 containing nitrogen

Abstract

A light emitting diode is provided having a Group III nitride based superlattice and a Group III nitride based active region on the superlattice. The active region has at least one quantum well structure. The quantum well structure includes a first Group III nitride based barrier layer, a Group III nitride based quantum well layer on the first barrier layer and a second Group III nitride based barrier layer. A Group III nitride based semiconductor device and methods of fabricating a Group III nitride based semiconductor device having an active region comprising at least one quantum well structure are provided. The quantum well structure includes a well support layer comprising a Group III nitride, a quantum well layer comprising a Group III nitride on the well support layer and a cap layer comprising a Group III nitride on the quantum well layer. A Group III nitride based semiconductor device is also provided that includes a gallium nitride based superlattice having at least two periods of alternating layers of In_XGa_1−XN and In_YGa_1−YN, where 0≦X<1 and 0≦Y<1 and X is not equal to Y. The semiconductor device may be a light emitting diode with a Group III nitride based active region. The active region may be a multiple quantum well active region.

Claims

1. A Group III nitride based light emitting diode, comprising:

a Group III nitride based superlattice comprising a gallium nitride based superlattice having at least two periods of alternating layers of In_XGa<sub>1−

X</sub>N and In_YGa<sub>1−

Y</sub>N, where 0≦

X<

1 and 0≦

Y<

1 and X is not equal to Y; and

a Group III nitride based active region on the superlattice comprising at least one quantum well structure comprising;

a first Group III nitride based barrier layer comprising a first well support layer comprising a Group III nitride;

a first Group III nitride based quantum well layer on the first barrier layer; and

a second Group III nitride based barrier layer on the first Group III nitride based quantum well layer comprising a first cap layer comprising a Group III nitride on the first quantum well layer;

a second well support layer comprising a Group III nitride on the cap layer;

a second quantum well layer comprising a Group III nitride on the second well support layer; and

a second cap layer comprising a Group III nitride on the second quantum well layer; and

wherein the cap layers have a lower crystal quality than the well support layers.

2. The light emitting diode of claim 1, wherein the at least one quantum well structure comprises from about 2 to about 10 repetitions of the at least one quantum well structure.

3. The light emitting diode according to claim 1, wherein the well support layer comprises a gallium nitride based layer, the quantum well layer comprises an indium gallium nitride layer and the barrier layer comprises a gallium nitride based layer.

4. The light emitting diode according to claim 1, wherein the well support layer and the cap layer comprises a layer of In_XGa₁₋

XN where 0≦

X<

1.

5. The light emitting diode according to claim 4, wherein an indium composition of the well support layer and the cap layer is less than an indium composition of the quantum well layer.

6. The light emitting diode according to claim 1, wherein the well support layer and the cap layer comprises a layer of Al_XIn_YGa₁₋

X−

YN where 0<

X<

1, 0≦

Y<

1 and X+Y≦

1.

7. The light emitting diode according to claim 6, wherein X≦

Y+0.05.

8. The light emitting diode according to claim 1, wherein the well support layers and the cap layers are undoped.

9. The light emitting diode according to claim 1, wherein the well support layers and the cap layers have a doping level of less than about 5×

10¹⁹ cm<sup>−

3</sup>.

10. The light emitting diode according to claim 1, wherein the cap layers and the well support layers have a higher bandgap than the quantum well layers.

11. The light emitting diode according to claim 1, wherein a combined thickness of the second well support layer and the first cap layer is from about 50 to about 400 Å

.

12. The light emitting diode according to claim 1, wherein a thickness of the well support layer is greater than a thickness of the cap layer.

13. The light emitting diode according to claim 1, wherein the quantum well layers have a thickness of from about 10 to about 50 Å

.

14. The light emitting diode according to claim 1, wherein the quantum well layers have a thickness of about 25 Å

.

15. The light emitting diode according to claim 1, wherein a percentage of indium in the quantum well layers is from about 5% to about 50%.

16. The light emitting diode according to claim 1, further comprising a Group III nitride based spacer layer between the first well support layer and the superlattice.

17. The light emitting diode according to claim 16, wherein the spacer layer comprises undoped GaN.

18. The light emitting diode according to claim 1, wherein a bandgap of the at least one quantum well is less than a bandgap of the superlattice.

19. The light emitting diode according to claim 1, wherein the gallium nitride based superlattice comprises from about 5 to about 50 periods.

20. The light emitting diode according to claim 1, wherein layers of In_XGa₁₋

XN and In_YGa<sub>1−

Y</sub>N of the alternating layers of In_XGa<sub>1−

X</sub>N and In_YGa<sub>1−

Y</sub>N have a combined thickness of less than about 70 Å

.

21. The light emitting diode according to claim 1, wherein X=0.

22. The light emitting diode according to claim 21, wherein InGaN layers of the alternating layers of In_XGa₁₋

XN and In_YGa<sub>1−

Y</sub>N have a thickness of from about 5 to about 40 Å and

GaN layers of the alternating layers of In_XGa<sub>1−

X</sub>N and In_YGa<sub>1−

Y</sub>N have a thickness of from about 5 to about 100 Å

.

23. The light emitting diode according to claim 21, wherein InGaN layers of the alternating layers of In_XGa₁₋

XN and In_YGa<sub>1−

Y</sub>N have a thickness of about 15 Å and

GaN layers of the alternating layers of ln_XGa<sub>1−

X</sub>N and In_YGa<sub>1−

Y</sub>N have a thickness of from about 30 Å

.

24. The light emitting diode according to claim 1, wherein the gallium nitride based superlattice is doped with an n-type impurity to a level of from about 1×

10¹⁷ cm<sup>−

3</sup> to about 5×

10 cm<sup>−

3</sup>.

25. The light emitting diode according to claim 24, wherein the doping level of the gallium nitride based superlattice is an actual doping level of layers of the alternating layers.

26. The light emitting diode according to claim 24, wherein the doping level is an avenge doping level of layers of the alternating layers.

27. The light emitting diode according to claim 1, further comprising doped Group III nitride layers adjacent the superlattice and wherein the doped Group III nitride layers are doped with an n-type impurity to provide an average doping of the doped Group III nitride layers and the superlattice of from about 1×

10¹⁷ cm<sup>−

3</sup> to about 5×

10¹⁹cm<sup>−

3</sup>.

28. The light emitting diode according to claim 1, wherein a bandgap of the superlattice is from about 2.95 eV to about 3.35 eV.

29. The light emitting diode according to claim 1, wherein a bandgap of the superlattice is about 3.15 eV.

30. A Group III nitride based semiconductor device having an active region comprising at least two stacked quantum well structures, the quantum well structures each comprising:

a well support layer comprising a Group III nitride;

a quantum well layer comprising a Group III nitride on the well support layer; and

a cap layer comprising a Group III nitride on the quantum well layer; and

wherein the cap layer has a lower crystal quality than the well support layer.

31. The Group III nitride based semiconductor device according to claim 30, wherein the well support layer comprises a gallium nitride based layer, the quantum well layer comprises an indium gallium nitride layer and the barrier layer comprises a gallium nitride based layer.

32. The Group III nitride based semiconductor device according to claim 31, wherein the well support layer and the cap layer comprises a layer of In_XGa₁₋

XN where 0≦

X<

1.

33. The Group III nitride based semiconductor device according to claim 32, wherein an indium composition of the well support layer and the cap layer is less an indium composition of the quantum well layer.

34. The Group III nitride based semiconductor device according to claim 31, wherein the well support layer and the cap layer comprises a layer of Al_XIn_YGa₁₋

X−

_YN where 0<

X<

1, 0≦

Y<

1 and X+Y≦

1.

35. The Group III nitride based semiconductor device according to claim 34, wherein X≦

Y+0.05.

36. The Group III nitride based semiconductor device according to claim 31, wherein the well support layer and the cap layer are undoped.

37. The Group III nitride based semiconductor device according to claim 31, wherein the well support layer and the cap layer have a doping level of less than about 5×

10¹⁹ cm<sup>−

3</sup>.

38. The Group III nitride based semiconductor device according to claim 30, wherein the cap layer and the well support layer have a higher bandgap than the quantum well layer.

39. The Group III nitride based semiconductor device according to claim 31, wherein a combined thickness of the well support layer and the cap layer is from about 50 to about 400 Å

.

40. The Group III nitride based semiconductor device according to claim 31, wherein a combined thickness of the well support layer and the cap layer is greater than about 90 Å

.

41. The Group III nitride based semiconductor device according to claim 31, wherein a combined thickness of the well support layer and the cap layer is about 225 Å

.

42. The Group III nitride based semiconductor device according to claim 31, wherein a thickness of the well support layer is greater than a thickness of the cap layer.

43. The Group III nitride based semiconductor device according to claim 31, wherein the quantum well layer has a thickness of from about 10 to about 50 Å

.

44. The Group III nitride based semiconductor device according to claim 31, wherein the quantum well layer has a thickness of about 25 Å

.

45. The Group III nitride based semiconductor device according to claim 31, wherein a percentage of indium in the quantum well layer is from about 5% to about 50%.

46. The Group III nitride based semiconductor device according to claim 31, further comprising a superlattice and wherein the well support layer is on the superlattice.

47. The Group III nitride based semiconductor device according to claim 46, wherein a bandgap of the superlattice is from about 2.95 to about 3.35 eV.

48. The Group III nitride based semiconductor device according to claim 46, wherein a bandgap of the superlattice is about 3.15 eV.

49. The Group III nitride based semiconductor device according to claim 46, further comprising a Group III nitride based spacer layer between the well support layer and the superlattice.

50. The Group III nitride based semiconductor device according to claim 49, wherein the spacer layer comprises undoped GaN.

51. The Group III nitride based semiconductor device according to claim 46, wherein a bandgap of the at least one quantum well is less than a bandgap of the superlattice.

52. The Group III nitride based semiconductor device according to claim 30 having from about 2 to about 10 repetitions of the quantum well structure.