Abstract: The invention relates to a semiconductor device, e.g. for the emission or absorption of light, preferably in the deep ultraviolet (DUV) range. The device, e.g. a resonant cavity light emitting diode (RCLED) or a laser diode, is formed from: a substrate layer (302), preferably comprising a distributed Bragg reflector (DBR); a graphitic layer (304); and at least one semiconductor structure (310), preferably a wire or a pyramid, grown on the graphitic layer, with or without the use of a mask layer (306). The semiconductor structure is constructed from at least one III-V semiconductor n-type doped region (316) and a hexagonal boron-nitride (hBN) region (312), preferably being p-type doped hBN.

Abstract: A composition of matter comprising: a plurality of group III-V nanowires or nanopyramids epitaxially grown on a polycrystalline or single-crystalline graphene layer, said graphene layer being directly supported on a crystalline substrate such as a group III-V semiconductor, sapphire, SiC or diamond substrate, wherein the epitaxy, crystal orientation and facet orientations of said nanowires or nanopyramids are directed by the crystalline substrate.