Readily Transferrable Growth of Crystallographically Aligned GaN Thin Film on Multilayer Graphene Transferred onto Sapphire Substrates by Thru-Hole Epitaxy

We heteroepitaxially grew GaN films on multilayer graphene transferred onto r-sapphire substrates. XRD measurement and analysis revealed that GaN films, grown on multilayer graphene transferred onto r-sapphire substrates, were crystallographically aligned with an underlying substrate. Despite well-established crystallographic alignment with the underlying substrate, the GaN films were easily detached from the graphene/sapphire template by using a thermal release tape. Due to the usage of thick graphene multilayers, the GaN films were not grown by remote epitaxy. Extensive TEM analysis across the interfacial regions showed that small holes in the nanometer scale played a major role in establishing both crystallographic alignment and easy detachability. In contrast with remote epitaxy, no strict conditions on the number of a layer or defect-free high quality for graphene were required for our growth method, thru-hole epitaxy.