▎ 摘　　要

Using physical insights and advanced first-principles calculations, we suggest that corundum (alpha-Al2O3) is an ideal gate dielectric material for graphene transistors. Clean interface exists between graphene and Al-terminated (or hydroxylated) Al2O3 and the valence-band offsets for these systems are large enough to create an injection barrier. Remarkably, a band gap of similar to 180 meV can be induced in a graphene layer adsorbed on an Al-terminated surface with an electron effective mass of similar to 8 x 10(-3) me. Moreover, the band gaps of a graphene/Al2O3 system could be tuned by an external electric field for practical applications.