Claims
- 1. A semiconductor structure for light emitting devices that can emit in the red to ultraviolet portion of the electromagnetic spectrum, said structure comprising:
a first n-type cladding layer of AlxInyGa1−x−yN, where 0≦x≦1 and 0≦y<1 and (x+y)≦1; a second n-type cladding layer of AlxInyGa1−x−yN where 0≦x≦1 and 0≦y<1 and (x+y)≦1, wherein said second n-type cladding layer is further characterized by the substantial absence of magnesium; an active portion between said first and second cladding layers in the form of a multiple quantum well having a plurality of InxGa1−xN well layers where 0<x<1 separated by a corresponding plurality of AlxInyGa1−x−yN barrier layers where 0≦x≦1 and 0≦y≦1 a p-type layer of a Group III nitride, wherein said second n-type cladding layer is positioned between said p-type layer and said multiple quantum well; wherein said first and second n-type cladding layers have respective bandgaps that are each larger than the bandgap of said well layers.
- 2. A structure according to claim 1 wherein said barrier layers comprise AlxInyGa1−x−yN where 0≦x<1 and 0<y<1.
- 3. A structure according to claim 1 wherein said barrier layers comprise AlxInyGa1−x−yN where 0<x<1 and 0≦y<1 and x+y≦1.
- 4. A structure according to claim 1 wherein said barrier layers in said multiple quantum well have larger bandgaps than said well layers in said multiple quantum well.
- 5. A structure according to claim 1 wherein at least one of said barrier layers in said multiple quantum well is undoped.
- 6. A structure according to claim 1 wherein at least one of said well layers in said multiple quantum well is undoped.
- 7. A semiconductor structure according to claim 1, wherein said multiple quantum well has a first surface and a second surface, said first surface of said multiple quantum well being in contact with said first n-type cladding layer and said second surface of said multiple quantum well being in contact with said second n-type cladding layer.
- 8. A semiconductor structure according to claim 1, wherein said second n-type cladding layer has a first surface and a second surface, said first surface of said second n-type cladding layer being in contact with said multiple quantum well, and said second surface of said second n-type cladding layer being in contact with said p-type layer, wherein the composition of said second n-type cladding layer is progressively graded such that the crystal lattice at said first surface of said second n-type cladding layer more closely matches the crystal lattice of said multiple quantum well, and the crystal lattice at said second surface of said second n-type cladding layer more closely matches the crystal lattice of said p-type layer.
- 9. A semiconductor structure according to claim 1, wherein said p-type layer is in contact with said second n-type cladding layer, opposite said multiple quantum well.
- 10. A semiconductor structure according to claim 1, wherein said second n-type cladding layer consists essentially of AlxGa1−xN, where 0<x <1.
- 11. A semiconductor structure according to claim 1, wherein said active layer consists essentially of InyGa1−yN, where 0<y<1.
- 12. A semiconductor structure according to claim 1, wherein said p-type layer is magnesium-doped gallium nitride.
- 13. A semiconductor structure according to claim 12, wherein said second n-type cladding layer is thick enough to deter migration of magnesium from said p-type layer to said multiple quantum well, yet thin enough to facilitate recombination in said multiple quantum well.
- 14. A semiconductor structure according to claim 1, wherein said p-type layer is indium nitride.
- 15. A semiconductor structure according to claim 1, wherein said p-type layer is InxGa1−xN, where 0<x<1.
- 16. A semiconductor structure according to claim 1, wherein said p-type layer comprises a superlattice formed from a plurality of Group III nitride layers selected from the group consisting of gallium nitride, indium nitride, and InxGa1−xN, where 0<x<1.
- 17. A semiconductor structure according to claim 16, wherein said superlattice is formed from alternating layers of two Group III nitride layers selected from the group consisting of gallium nitride, indium nitride, and InxGa1−xN, where 0<x<1.
- 18. A semiconductor structure according to claim 1, further comprising a third n-type layer of AlxInyGa1−x−yN, where 0≦x≦1 and 0≦y<1 and (x+y)≦1, wherein said third n-type layer is positioned between said second n-type cladding layer and said p-type layer.
- 19. A semiconductor structure according to claim 18, wherein said third n-type layer has a first surface and a second surface, said first surface of said third n-type layer being in contact with said p-type layer and said second surface of said third n-type layer being in contact with said second n-type cladding layer.
- 20. A semiconductor structure according to claim 1, further comprising an n-type silicon carbide substrate, wherein said first n-type cladding layer is positioned between said silicon carbide substrate and said multiple quantum well.
- 21. A semiconductor structure according to claim 15, further comprising discrete crystal portions selected from the group consisting of gallium nitride and indium gallium nitride, said discrete crystal portions positioned between said first n-type cladding layer and said silicon carbide substrate, said discrete crystal portions being present in an amount sufficient to reduce the barrier between said first n-type cladding layer and said silicon carbide substrate, but less than an amount that would detrimentally affect the function of any resulting light emitting device formed on said silicon carbide substrate.
- 22. A semiconductor structure according to claim 1, further comprising:
an n-type-silicon carbide substrate; and a conductive buffer layer positioned between said silicon carbide substrate and said first n-type cladding layer.
- 23. A semiconductor structure according to claim 22, wherein said conductive buffer layer has a first surface and a second surface, said first surface of said conductive buffer layer being in contact with said silicon carbide substrate and said second surface of said conductive buffer layer being in contact with said first n-type cladding layer.
- 24. A semiconductor structure according to claim 22, wherein said conductive buffer layer consists essentially of aluminum gallium nitride having the formula AlxGa1−xN, where 0<x<1.
- 25. A semiconductor structure according to claim 22, further comprising an n-type transition layer of a Group III nitride, said transition layer being positioned between said conductive buffer layer and said first n-type cladding layer.
- 26. A semiconductor structure according to claim 22, further comprising discrete crystal portions selected from the group consisting of gallium nitride and indium gallium nitride, said discrete crystal portions positioned between said conductive buffer layer and said silicon carbide substrate, said discrete crystal portions being present in an amount sufficient to reduce the barrier between said conductive buffer layer and said silicon carbide substrate, but less than an amount that would detrimentally affect the function of any resulting light emitting device formed on said silicon carbide substrate.
- 27. A semiconductor structure for light emitting devices that can emit in the red to ultraviolet portion of the electromagnetic spectrum, said structure comprising:
an n-type single crystal silicon carbide substrate of a polytype selected from the group consisting of 3C, 4H, 6H, and 15R; a p-type layer formed of at least one Group III nitride selected from the group consisting of gallium nitride, indium nitride, and InxGa1−xN, where 0<x<1; an active portion between said substrate and said p-type layer in the form of a multiple quantum well having a plurality of InxGa1−xN well layers where 0<x<1 separated by a corresponding plurality of AlxInyGa1−x−yN barrier layers where 0≦x≦1 and 0≦y≦1 a first n-type cladding layer of AlxInyGa1−x−yN, where 0≦x≦1 and 0≦y<1 and (x+y)≦1, wherein said first n-type cladding layer is positioned between said silicon carbide substrate and said multiple quantum well; a second n-type cladding layer of AlxInyGa1−x−yN, where 0≦x≦1 and 0≦y<1 and (x+y)≦1, wherein said second n-type cladding layer is positioned between said multiple quantum well and said p-type layer; wherein said first and second n-type cladding layers have respective bandgaps that are each larger than the bandgap of said wells in said multiple quantum well.
- 28. A structure according to claim 27 wherein said barrier layers comprise AlxInyGa1−x−yN where 0≦x<1 and 0<y<1.
- 29. A structure according to claim 27 wherein said barrier layers comprise AlxInyGa1−x−yN where 0<x<1 and 0≦y<1 and x+y≦1.
- 30. A structure according to claim 27 wherein said barrier layers in said multiple quantum well have larger bandgaps than said well layers in said multiple quantum well.
- 31. A structure according to claim 27 wherein at least one of said barrier layers in said multiple quantum well is undoped.
- 32. A structure according to claim 27 wherein at least one of said well layers in said multiple quantum well is undoped.
- 33. A semiconductor structure according to claim 27, wherein said first n-type cladding layer has a first surface and a second surface, said first surface of said first n-type cladding layer being in contact with said silicon carbide substrate, and said second surface of said first n-type cladding layer being in contact with said multiple quantum well, wherein the composition of said first n-type cladding layer is progressively graded such that the crystal lattice at said first surface of said first n-type cladding layer more closely matches the crystal lattice of said substrate, and the crystal lattice at said second surface of said first n-type cladding layer more closely matches the crystal lattice of said multiple quantum well.
- 34. A semiconductor structure according to claim 27, wherein said second n-type cladding layer has a first surface and a second surface, said first surface of said second n-type cladding layer being in contact with said multiple quantum well, and said second surface of said second n-type cladding layer being in contact with said p-type layer, wherein the composition of said second n-type cladding layer is progressively graded such that the crystal lattice at said first surface of said second n-type cladding layer more closely matches the crystal lattice of said multiple quantum well, and the crystal lattice at said second surface of said second n-type cladding layer more closely matches the crystal lattice of said p-type layer.
- 35. A semiconductor structure according to claim 27, wherein said p-type layer is magnesium-doped gallium nitride.
- 36. A semiconductor structure according to claim 35, wherein said second n-type cladding layer is thick enough to deter migration of magnesium from said p-type layer to said multiple quantum well, yet thin enough to facilitate recombination in said multiple quantum well.
- 37. A semiconductor structure according to claim 27, wherein said p-type layer comprises a superlattice formed from alternating layers of two Group III nitride layers selected from the group consisting of gallium nitride, indium nitride, and InxGa1−xN, where 0<x<1.
- 38. A semiconductor structure according to claim 27, further comprising a third n-type layer of AlxInyGa1−x−yN, where 0≦x≦1 and 0≦y<1 and (x+y)≦1, wherein said third n-type layer is positioned between said second n-type cladding layer and said p-type layer.
- 39. A semiconductor structure according to claim 27, wherein said third n-type layer has a first surface and a second surface, said first surface of said third n-type layer being in contact with said p-type layer and said second surface of said third n-type layer being in contact with said second n-type cladding layer.
- 40. A semiconductor device according to claim 27, further comprising a conductive buffer layer consisting essentially of aluminum gallium nitride having the formula AlxGa1−xN, where 0≦x≦1, said conductive buffer layer positioned between said silicon carbide substrate and said first n-type cladding layer.
- 41. A semiconductor structure according to claim 40, further comprising an n-type transition layer of a Group III nitride, said transition layer being positioned between said conductive buffer layer and said first n-type cladding layer, and having the same conductivity type as said first n-type cladding layer.
- 42. A semiconductor structure according to claim 27, further comprising discrete crystal portions selected from the group consisting of gallium nitride and indium gallium nitride, said discrete crystal portions positioned between said first n-type cladding layer and said silicon carbide substrate, said discrete crystal portions being present in an amount sufficient to reduce the barrier between said first n-type cladding layer and said silicon carbide substrate, but less than an amount that would detrimentally affect the function of any resulting light emitting device formed on said silicon carbide substrate.
- 43. A semiconductor structure for light emitting devices that can emit in the red to ultraviolet portion of the electromagnetic spectrum, said structure comprising:
an active portion in the form of a multiple quantum well having a plurality of InxGa1−xN well layers where 0<x<1 separated by a corresponding plurality of AlxInyGa1−x−yN barrier layers where 0≦x≦1 and 0≦y≦1 a Group III nitride superlattice supporting said multiple quantum well; a layer of AlxInyGa1−x−yN, where 0≦x≦1 and 0≦y<1 and (x+y)≦1 adjacent said multiple quantum well and opposite from said superlattice with respect to said multiple quantum well and being characterized by the substantial absence of magnesium; a first p-type layer of a Group III nitride adjacent said AlInGaN layer and opposite said multiple quantum well with respect to said AlInGaN layer; and an n-type Group III nitride layer supporting said superlattice and opposite from said multiple quantum well with respect to said superlattice.
- 44. A semiconductor structure according to claim 43 and further comprising a silicon carbide substrate and a conductive Group III nitride buffer layer on said substrate, with said substrate and said conductive buffer layer supporting the remainder of said structure.
- 45. A semiconductor structure according to claim 44 and further comprising:
an additional n-type GaN layer between said conductive buffer layer and said supporting n-type layer; a p-type contact layer on said first p-type layer; an ohmic contact to said p-type contact layer; and an ohmic contact to said substrate.
- 46. A semiconductor structure according to claim 43 wherein said superlattice comprises alternating layers of InxGa1−xN and InyGa1−yN where 0≦x≦1 and 0≦y≦1 and x does not equal y.
- 47. A semiconductor structure according to claim 46 wherein x equals 0 and 0<y <1.
- 48. A semiconductor structure according to claim 46 wherein said superlattice contains between 5 and 50 periods.
- 49. A semiconductor structure according to claim 46 wherein said superlattice contains 25 periods.
- 50. A semiconductor structure according to claim 46 wherein said superlattice contains 10 periods.
- 51. A semiconductor structure for light emitting devices that can emit in the red to ultraviolet portion of the electromagnetic spectrum, said structure comprising:
a silicon carbide substrate; a conductive Group III nitride buffer layer on said substrate; a first n-type GaN layer on said conductive buffer layer; a second n-type Group III nitride layer on said first GaN layer; a superlattice on said second GaN layer and formed of alternating layers of GaN and InyGa1−yN where 0<y<1; an active portion on said superlattice in the form of a multiple quantum well having a plurality of InxGa1−xN well layers where 0<x<1 separated by a corresponding plurality of AlxInyGa1−x−yN barrier layers where 0≦x≦1 and 0≦y≦1 a layer of AlxInyGa1−x−yN, where 0≦x≦1 and 0≦y<1 and (x+y)≦1 on said multiple quantum well and being characterized by the substantial absence of magnesium; a first p-type layer of a Group III nitride on said AlInGaN layer; a p-type contact layer on said first p-type layer; an ohmic contact to said p-type contact layer; and an ohmic contact to said substrate.
- 52. A structure according to claim 51 wherein said barrier layers in said multiple quantum well have larger bandgaps than said well layers in said multiple quantum well.
- 53. A structure according to claim 51 wherein at least one of said barrier layers in said multiple quantum well is undoped.
- 54. A structure according to claim 51 wherein at least one of said well layers in said multiple quantum well is undoped.
- 55. A semiconductor structure according to claim 51, further comprising discrete crystal portions selected from the group consisting of gallium nitride and indium gallium nitride, said discrete crystal portions positioned between said first n-type cladding layer and said silicon carbide substrate, said discrete crystal portions being present in an amount sufficient to reduce the barrier between said first n-type cladding layer and said silicon carbide substrate, but less than an amount that would detrimentally affect the function of any resulting light emitting device formed on said silicon carbide substrate.
Parent Case Info
[0001] This is a continuation in part of application Ser. No. 09/760,635 filed Jan. 16, 2001 for, “Group III Nitride LED with Undoped Cladding Layer.” This application also claims priority from Provisional Application No. 60/294,445 filed May 30, 2001 for, “Multi-Quantum Well Light Emitting Diode Structure.” This application incorporates entirely by reference co-pending and commonly-assigned applications Ser. No. 09/706,057 filed Nov. 3, 2000 for “Group III Nitride Light Emitting Devices with Gallium-Free Layers,” and Ser. No. 60/298,835 filed Jun. 15, 2001 for “Ultraviolet Light Emitting Diode.”
Provisional Applications (1)
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Number |
Date |
Country |
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60294445 |
May 2001 |
US |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
09760635 |
Jan 2001 |
US |
Child |
10159893 |
May 2002 |
US |