Graphene Field-Effect Transistors with High On/Off Current Ratio and Large Transport Band Gap at Room Temperature

Graphene is considered to be a promising candidate for future nanoelectronics due to its exceptional electronic properties. Unfortunately, the graphene field-effect transistors (FETs) cannot be turned off effectively due to the absence of a band gap, leading to an on/off current ratio typically around 5 in top-gated graphene FETs. On the other hand, theoretical investigations and optical measurements suggest that a band gap up to a few hundred millielectronvolts can be created by the perpendicular E-field in bilayer graphenes. Although previous carrier transport measurements in bilayer graphene transistors did indicate a gate-induced insulating state at temperatures below 1 K, the electrical (or transport)…