Direct Growth of Graphene/Graphene Oxide Heterostructures on Polar Oxide Substrates

Direct graphene growth—without physical transfer—by C molecular beam epitaxy has been reported on two incommensurate polar oxide substrates: Co3O4(111) and MgO(111). Recent experimental and theoretical work regarding graphene growth on Co3O4(111) indicates that growth proceeds via the initial formation of a graphene oxide buffer layer formed by C covalent bond formation to oxygen sites on the cobalt oxide substrate. This finding motivates a reinterpretation of previously reported results for graphene growth on MgO(111). This reinterpretation indicates that formation of a non-planar graphene oxide buffer layer occurs for growth on MgO(111), similar to that on Co3O4(111). Results suggest that the formation of a graphene oxide buffer layer on MgO(111), rather than reconstruction of the MgO(111) surface, is what leads to the observed C3v symmetry and substantial band gap for the C overlayer on that substrate. Prospects for direct growth on other polar oxide surfaces and implications for device applications are discussed.