Alternative doping for group III nitride LEDs

1. In a light emitting diode formed in the Group III nitride material system that includes respective n-type and p-type layers for current injection and light emission; the improvement comprising:

an n-type Group III nitride layer comprising dopants selected from the group consisting of germanium and tellurium; and

said n-type Group III nitride layer doped with germanium or tellurium having a thickness that is between two boundaries:

an upper boundary defined by the maximum thickness at which said n-type Group III nitride layer when doped with germanium or tellurium is pseudomorphic on a defined growth substrate; and

a lower boundary defined by the maximum thickness at which the same n-type Group III nitride layer when doped only with silicon is pseudomorphic on the same defined growth substrate.

2. A light emitting diode according to claim 1 comprising:

a Group III nitride emission layer on said n-type Group III nitride layer; and

a p-type Group III nitride on said Group III nitride emissions layer for providing a p-n junction structure for current injection through the device and generating an emission.

3. A light emitting diode according to claim 1 wherein said n-type Group III nitride layer is selected from the group consisting of gallium nitride, indium nitride, aluminum gallium nitride, and aluminum indium gallium nitride.

4. A light emitting diode according to claim 2 further comprising respective ohmic contacts to said p-type Group III nitride and said n-type Group III nitride layer.

5. A light emitting diode according to claim 4 wherein said n-type Group III nitride layer is supported by a conductive n-type silicon carbide substrate and said ohmic contact to said n-type layer is made to said n-type silicon carbide substrate.

6. A light emitting diode comprising:

a silicon carbide substrate;

a Group III nitride buffer structure on said silicon carbide substrate;

an n-type Group III nitride epitaxial layer on said buffer structure;

a Group III nitride superlattice structure on said n-type Group III nitride epitaxial layer;

said n-type Group III nitride epitaxial layer in said diode being doped with a dopant selected from the group consisting of germanium and tellurium; and

said n-type Group III nitride epitaxial layer doped with germanium or tellurium having a thickness that is between two boundaries:

an upper boundary defined by the maximum thickness at which said n-type Group III nitride epitaxial layer when doped with germanium or tellurium is pseudomorphic on a defined growth substrate; and

a lower boundary defined by the maximum thickness at which the same n-type Group III nitride layer when doped only with silicon is pseudomorphic on the same defined growth substrate.

7. A light emitting diode according to claim 6 wherein said superlattice comprises a series of at least two alternating strained layers of Group III nitride materials.

8. A light emitting diode according to claim 6 wherein said n-type Group III nitride layer comprises gallium nitride.

9. A light emitting diode according to claim 6 wherein said buffer structure includes an n-type layer of aluminum gallium nitride between said substrate and said n-type Group III nitride epitaxial layer.

10. A light emitting diode according to claim 9 wherein said n-type layer of aluminum gallium nitride is doped with germanium or tellurium.

11. A light emitting diode according to claim 10 in which said aluminum gallium nitride buffer layer is graded in its atomic percentage of aluminum between said substrate and said n-type Group III nitride epitaxial layer.

12. A light emitting diode according to claim 6 wherein said buffer structure includes a plurality of discontinuous portions of Group III nitride material for enhancing the structural and electronic transition between said silicon carbide substrate and said n-type Group III nitride epitaxial layer.

13. A light emitting diode according to claim 12 wherein said discontinuous portions comprise gallium nitride dots.

14. A light emitting diode according to claim 6 wherein said buffer structure includes both a graded layer of aluminum gallium nitride and a homogeneous layer of aluminum gallium nitride between said substrate and said n-type Group III nitride epitaxial gallium nitride layer.

15. A light emitting diode according to claim 6 comprising ohmic contacts to said n-type Group III nitride epitaxial layer and said superlattice for injecting current through said diode.

16. A light admitting diode according to claim 15 in a vertical orientation with one of said ohmic contracts on said silicon carbide substrate and the other of said ohmic contacts to said superlattice opposite said substrate.

17. A light emitting diode according to claim 15 comprising two top side ohmic contacts.

18. In a light emitting diode formed in the Group III nitride material system that includes respective n-type and p-type layers for current injection and light emission; the improvement comprising:

an n-type Group III nitride layer that includes silicon and a dopant selected from the group consisting of elements with a larger atomic radius than silicon and elements with a larger covalent radius than silicon; and

said n-type Group III nitride layer having a thickness that is between two boundaries:

an upper boundary defined by the maximum thickness at which said n-type Group III nitride layer is pseudomorphic on a defined growth substrate; and

a lower boundary defined by the maximum thickness at which the same n-type Group III nitride layer when doped only with silicon is pseudomorphic on the same defined growth substrate.

19. A light emitting diode according to claim 18 wherein said group of elements with larger radius comprises germanium and tellurium.

20. A light emitting diode according to claim 18 wherein the relative amount of silicon doping and larger atom doping progressively changes across said n-type Group III nitride layer.

21. A semiconductor device, comprising:

at least one n-type Group III nitride layer that includes silicon and a dopant having at least one characteristic selected from the group consisting of a larger atomic radius than silicon and a larger covalent radius than silicon.

22. A semiconductor device according to claim 21 wherein a relative amount of said silicon and said dopant progressively changes across said at least one Group III nitride layer.