Abstract: A light emitting diode device comprising: a plurality of nanowires or nanopyramids grown on a graphitic substrate, said nanowires or nanopyramids having a p-n or p-i-n junction, a first electrode in electrical contact with said graphitic substrate; a light reflective layer in contact with the top of at least a portion of said nanowires or nanopyramids, said light reflective layer optionally acting as a second electrode; optionally a second electrode in electrical contact with the top of at least a portion of said nanowires or nanopyramids, said second electrode being essential where said light reflective layer does not act as an electrode; wherein said nanowires or nanopyramids comprise at least one group III-V compound semiconductor; and wherein in use light is emitted from said device in a direction substantially opposite to said light reflective layer.

Abstract: 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.

Abstract: A composition of matter comprising: a graphitic substrate optionally carried on a support, a seed layer having a thickness of no more than 50 nm deposited directly on top of said substrate, opposite any support; and an oxide or nitride masking layer e directly on top of said seed layer; wherein a plurality of holes are present through said seed layer and through said masking layer to C said graphitic substrate; and wherein a plurality of nanowires or nanopyramids are grown from said substrate in said holes, said nanowres or nanopyramids comprising at least one semiconducting group III-V compound.

Abstract: 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.

Abstract: A composition of matter comprising: a graphitic substrate optionally carried on a support; a seed layer having a thickness of no more than 50 nm deposited directly on top of said substrate, opposite any support; and an oxide or nitride masking layer directly on top of said seed layer; wherein a plurality of holes are present through said seed layer and through said masking layer to said graphitic substrate; and wherein a plurality of nanowires or nanopyramids are grown from said substrate in said holes, said nanowires or nanopyramids comprising at least one semiconducting group III-V compound.