First-principles prediction of graphene/SnO2 heterostructure as a promising candidate for FET

Very recently, graphene/SnO2 heterostructures (G/SnO2 HTSs) were successfully synthesized experimentally. Motivated by this work, the adhesion and electronic properties of G/SnO2 HTSs have been studied by using first-principles calculations. It is found that the graphene interacts overall with the SnO2 monolayer with a binding energy of similar to 67-similar to 70 meV per carbon atom, suggesting a weak van der Waals interaction between graphene and the SnO2 substrate. Although the global band gap is zero, a sizable band gap of 10.2-12.6 meV at the Dirac point is obtained in all G/SnO2 HTSs, mainly determined by the distortion of isolated graphene peeled from the SnO2 monolayer, independent of the SnO2 substrate. When the bilayer graphene is deposited on the SnO2 substrate, however, a global gap of 100 meV is formed at the Fermi level, which is large enough for the gap opening at room temperature. Interestingly, the characteristics of the Dirac cone with a nearly linear band dispersion relation of graphene can be preserved, accompanied by a small electron effective mass, and thus higher carrier mobility is expected. These finds provide a better understanding of the interfacial properties of G/SnO2 HTSs and will help to design high-performance FETs in nanoelectronics.