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 -67 - 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.