Modeling and simulation of graphene devices

Graphene has been explored as one of the promising materials to sustain Moore's law especially with silicon approaching its limits. The extraordinary electronic properties of graphene like high mobility, high saturation velocity etc. have created a gold rush for graphene based electronics. The numerical study in this dissertation provides valuable insights into device physics and characteristics of graphene Field Effect Transistors (FETs).;First part of dissertation studies the effect of inelastic phonon scattering in graphene FETs using semi classical approach. A kink behavior due to ambipolar transport is observed. Even the low field mobility is affected by inelastic phonon scattering in recent graphene FET experiments reporting high mobilities. Physical mechanisms for good linearity are explained.;The high frequency performance limits of graphene FETs are studied by running quantum simulations. Although Klein band-to-band tunneling is significant for sub-100nm graphene FETs, it is possible to achieve a good transconductance and ballistic on-off ratio larger than 3 even at a channel length of 20nm. At a channel length of 20nm, the intrinsic cut-off frequency remains at a couple of THz for various gate insulator thickness values, but a thin gate insulator is necessary for a good transconductance and smaller degradation of cut-off frequency in the presence of parasitic capacitance. With a thin high-kappa gate insulator, the intrinsic ballistic fT is above 5THz for gate length of 10nm. The source and drain resistance severely degrade RF parameters, fMAX and f T. It is found that the intrinsic fT is close to the LC characteristic frequency set by graphene kinetic inductance and quantum capacitance.;Graphene on silicon contacts are modeled. Graphene on silicon forms Schottky contact with a flexibility to tune the Schottky barrier height (SBH) by silicon doping and gate voltage. Multiple layers of graphene at the interface as well as donor type interface states reduce the gate modulation.;Last subject investigates the thermoelectric transport properties of graphene FETs in presence of elastic and surface polar phonon scattering. It is found that scattering reduces the thermoelectric power. In addition, surface polar phonon scattering also degrades the symmetry of TEP with respect to the Dirac point.