  A graphene field effect transistor, where the active area is made of
monolayer large-area graphene, is simulated including a full 2D Poisson
equation and a drift-diffusion model with mobilities deduced by a direct
numerical solution of the semiclassical Boltzmann equations for charge
transport by a suitable discontinuous Galerkin approach.
  The critical issue in a graphene field effect transistor is the difficulty of
fixing the off state which requires an accurate calibration of the gate
voltages. In the present paper we propose and simulate a graphene field effect
transistor structure which has well-behaved characteristic curves similar to
those of conventional (with gap) semiconductor materials. The introduced device
has a clear off region and can be the prototype of devices suited for
post-silicon nanoscale electron technology. The specific geometry overcomes the
problems of triggering the minority charge current and gives a viable way for
the design of electron devices based on large area monolayer graphene as
substitute of standard semiconductors in the active area. The good field effect
transistor behavior of the current versus the gate voltage makes the simulated
device very promising and a challenging case for experimentalists.
