Graphene Field-Effect Transistor on a Calcium Fluoride Substrate

摘要

We report the electrical-transport properties of a monolayer graphene device put on a 500 μm-thick calcium fluoride (CaF_(2)) single-crystal substrate. From the gate-voltage dependence, clear n -type behavior was observed in a graphene/CaF_(2)field-effect transistor. This can be understood on the basis of the strong interaction between graphene and the CaF_(2)substrate, where the substantial electron wavefunction overlap between graphene and fluorine atoms of CaF_(2)occurs. This observation indicates that the strong n -type doping to graphene is possible only through the contact of graphene with the fluorinated substrate due to the strong electron affinity of a fluorine atom. Various electrical and optical characterizations for the graphene on CaF_(2)substrates are provided.