Analysis of Graphene Tunnel Field-Effect Transistors for Analog/RF Applications

The recent findings of quasi-saturation and negative differential resistance in graphene FET have motivated the researchers to improve the current saturation behavior. We suggest that tunnel FET (TFET) with graphene can be a potential candidate for better current saturation. In this regard, the electronic transport in zero bandgap graphene TFET (T-GFET) is studied through the self-consistent solution of Schrödinger equation within ballistic nonequilibrium Green´s function formalism, and 2-D Poisson´s equation. We show that the appropriate drain overlap, and channel and drain doping concentrations in T-GFET can significantly suppress the channel to drain tunneling current and, consequently, enhance the current saturation. Despite T-GFET´s lower ON-current, it shows moderately higher intrinsic gain, compared with conventional graphene FET (C-GFET). Furthermore, the channel length dependence of intrinsic gain and cutoff frequency for T-GFET is investigated and compared with C-GFET.