Device Physics and Characteristics of Graphene Nanoribbon Tunneling FETs

We present a detailed simulation study on the current-voltage characteristics of ballistic graphene nanoribbon (GNR) tunneling FETs of different widths with varying temperatures and channel length. Our model uses the self-consistent nonequilibrium Green´s function and the quasi-2-D Poisson solver with the material details of the GNRs modeled by the uncoupled mode space Dirac equation. We find that, in general, the GNR tunneling FETs from the 3p + 1 family have better I_ON/I_OFF characteristics than those from the 3p family due to smaller effective masses of the former. A lower drain doping concentration relative to that of the source enhances the I_ON/I_OFF. Most significantly, we find that a higher doping concentration at the source enhances I_ON but degrades the subthreshold swing (SS). As a function of temperature, the SS shows highly nonlinear behaviors. In terms of intrinsic delay and power-delay product, the GNR tunneling FETs show very promising scaling behaviors and can be optimized to meet the International Technology Roadmap for Semiconductors roadmap requirements through adjustment in doping concentrations and other parameters.