Process for growing nanowires or nanopyramids on graphitic substrates
A process for growing nanowires or nanopyramids comprising: (I) providing a graphitic substrate and depositing AlGaN, InGaN, AlN or AlGa(In)N on said graphitic substrate at an elevated temperature to form a buffer layer or nanoscale nucleation islands of said compounds; (II) growing a plurality of semiconducting group III-V nanowires or nanopyramids, preferably III-nitride nanowires or nanopyramids, on the said buffer layer or nucleation islands on the graphitic substrate, preferably via MOVPE or MBE.
1. A process for growing nanowires or nanopyramids comprising:
(I) providing a graphitic substrate and depositing AlGaN, InGaN, AlN or AlGa(In)N on said graphitic substrate at an elevated temperature to form nanoscale nucleation islands of AlGaN, InGaN, AlN or AlGa(In)N; and
(II) growing a plurality of semiconducting group III-V nanowires or nanopyramids on the nanoscale nucleation islands on the graphitic substrate, wherein the plurality of semiconducting group III-V nanowires or nanopyramids are grown axially and are therefore formed from a first section and a second section, wherein the first section and the second section are each doped with a different dopant to generate a p-n junction or p-i-n junction.
2. The process as claimed in claim 1 , wherein the plurality of semiconducting group III-V nanowires or nanopyramids are grown epitaxially from the nanoscale nucleation islands.
3. The process as claimed in claim 1 , wherein said graphitic substrate has a thickness of up to 20 nm.
4. The process as claimed in claim 1 , wherein a graphitic top contact layer is present on top of the plurality of semiconducting group III-V nanowires or nanopyramids.
5. The process as claimed in claim 1 , wherein the plurality of semiconducting group III-V nanowires or nanopyramids are grown with or without the presence of a catalyst.
6. The process as claimed in claim 1 , wherein the plurality of semiconducting group III-V nanowires or nanopyramids are GaN, AlGaN, AlN or InGaN.
7. The process as claimed in claim 1 , wherein the plurality of semiconducting group III-V nanowires are grown in the [111] (for cubic crystal structure) or (for hexagonal crystal structure) direction.
8. The process as claimed in claim 1 , wherein the plurality of semiconducting group III-V nanowires or nanopyramids comprise a tunnel junction.
9. An electronic device comprising a product obtained by the process as claimed in claim 1 , wherein the electronic device comprises a solar cell, photodetector, or LED.
10. The process as claimed in claim 1 , wherein the plurality of semiconducting group III-V nanowires or nanopyramids comprise a plurality of group III-nitride nanowires or nanopyramids.
11. The process as claimed in claim 1 , wherein the plurality of semiconducting group III-V nanowires or nanopyramids are grown via MOVPE or MBE.
12. A process for growing nanowires or nanopyramids comprising:
(I) providing a graphitic substrate and depositing AlGaN, InGaN, AlN or AlGa(In)N on said graphitic substrate at an elevated temperature to form nanoscale nucleation islands of AlGaN, InGaN, AlN or AlGa(In)N; and
(II) growing a plurality of semiconducting group III-V nanowires or nanopyramids on the nanoscale nucleation islands on the graphitic substrate, wherein the plurality of semiconducting group III-V nanowires or nanopyramids comprise an (Al)GaN/Al(Ga)N superlattice.
13. The process as claimed in claim 12 , wherein the plurality of semiconducting group III-V nanowires or nanopyramids are grown epitaxially from the nanoscale nucleation islands.
14. The process as claimed in claim 12 , wherein said graphitic substrate has a thickness of up to 20 nm.
15. The process as claimed in claim 12 , wherein the plurality of semiconducting group III-V nanowires or nanopyramids are doped.
16. The process as claimed in claim 12 , wherein the plurality of semiconducting group III-V nanowires or nanopyramids are core-shell nanowires or nanopyramids.
17. The process as claimed in claim 12 , wherein a graphitic top contact layer is present on top of the plurality of semiconducting group III-V nanowires or nanopyramids.
18. The process as claimed in claim 12 , wherein the plurality of semiconducting group III-V nanowires or nanopyramids are grown with or without the presence of a catalyst.
19. The process as claimed in claim 12 , wherein the plurality of semiconducting group III-V nanowires are grown in the [111] (for cubic crystal structure) or (for hexagonal crystal structure) direction.
20. The process as claimed in claim 12 , wherein the plurality of semiconducting group III-V nanowires or nanopyramids comprise a tunnel junction.
21. The process as claimed in claim 12 , wherein the plurality of semiconducting group III-V nanowires or nanopyramids comprise AlGaN and wherein each of the plurality of semiconducting AlGaN nanowires or nanopyramids has a concentration of Al that increases or decreases along an axial growth direction and/or a radial growth direction of the nanowire or nanopyramid.
22. An electronic device comprising a product obtained by the process as claimed in claim 12 , wherein the electronic device comprises a solar cell, photodetector, or LED.
23. The process as claimed in claim 12 , wherein the plurality of semiconducting group III-V nanowires or nanopyramids are grown via MOVPE or MBE.
24. A process for growing nanowires or nanopyramids comprising:
(I) providing a graphitic substrate and depositing AlGaN, InGaN, AlN or AlGa(In)N on said graphitic substrate at an elevated temperature to form nanoscale nucleation islands of AlGaN, InGaN, AlN or AlGa(In)N; and
(II) growing a plurality of semiconducting group III-V nanowires or nanopyramids on the nanoscale nucleation islands on the graphitic substrate, wherein the plurality of semiconducting group III-V nanowires or nanopyramids comprise AlGaN and wherein each of the plurality of semiconducting AlGaN nanowires or nanopyramids has a concentration of Al that increases or decreases along an axial growth direction and/or a radial growth direction of the nanowire or nanopyramid.
25. The process as claimed in claim 24 , wherein the plurality of semiconducting group III-V nanowires or nanopyramids are grown epitaxially from the nanoscale nucleation islands.
26. The process as claimed in claim 24 , wherein said graphitic substrate has a thickness of up to 20 nm.
27. The process as claimed in claim 24 , wherein the plurality of semiconducting group III-V nanowires or nanopyramids are doped.
28. The process as claimed in claim 24 , wherein a graphitic top contact layer is present on top of the plurality of semiconducting group III-V nanowires or nanopyramids.
29. The process as claimed in claim 24 , wherein the plurality of semiconducting group III-V nanowires or nanopyramids are grown with or without the presence of a catalyst.
30. The process as claimed in claim 24 , wherein the plurality of semiconducting group III-V nanowires are grown in the [111] (for cubic crystal structure) or (for hexagonal crystal structure) direction.
31. The process as claimed in claim 24 , wherein the plurality of semiconducting group III-V nanowires or nanopyramids comprise a tunnel junction.
32. An electronic device comprising a product obtained by the process as claimed in claim 24 , wherein the electronic device comprises a solar cell, photodetector, or LED.
33. The process as claimed in claim 24 , wherein the plurality of semiconducting group III-V nanowires or nanopyramids are grown via MOVPE or MBE.