Research at the Norwegian University of Science and Technology have grown GaAs nanowires on an epitaxial graphene layer using a MBE system. Ga is first deposited onto the graphene substrate and it forms nanoparticles that align with the graphene lattice. As is then introduce and the nanowires then grow without further catalysts. The nanowires form an array and are attached to the graphene substrate that is flexible and transparent. The details of the work can be found in Vertically Aligned GaAs Nanowires on Graphite and Few-Layer Graphene: Generic Model and Epitaxial Growth and can be seen in this interesting video.