Simulation of Graphene Field Effect Transistors

Field effects transistors, where the active region is constituted by a single layer of graphene, are simulated and the characteristic curves are shown. The current–voltage curves present a behaviour different from that of devices made of classical semiconductors, like Si or GaAs, because of the zero gap in monolayer graphene. The current is no longer a monotone function of the gate voltage but there exists an inversion gate voltage corresponding to which the type of majority carriers changes. Usually the considered devices are investigated by adopting reduced one dimensional models with some averaging procedure. Here a full two-dimensional simulation is presented. The model is based on a system of drift-diffusion equations for electrons and holes. The numerical method is based on the Scharfettel and Gummel scheme. A special treatment of the Poisson equation is adopted for taking into account the charge in the graphene sheet. The characteristic curves for fixed gate voltages and for fixed source-drain voltages have been obtained.