Geometries and electronic structures of graphene adsorbed on SiO2 (0001) surfaces: The possibility of electronic structure tuning by an insulating substrate

We demonstrate the possibility of electron-state tuning of graphene adsorbed on (0001) surfaces of SiO₂ by using first-principles total-energy calculations. Our calculations suggest that graphene is bound on SiO₂ surfaces via weak van der Waals interactions irrespective of surface morphology. In all arrangements of graphene on the different SiO₂ surfaces, graphene possesses a small energy gap of up to a few tens of meV at the Dirac cone depending on surface morphology. This suggests a possible application in next-generation electronic nanodevices. In addition to the semiconducting properties with the substantial energy gap, several surface morphologies lead to p-type doping in graphene.