A computational study of vertical tunneling transistors based on graphene-WS_2 heterostructure

摘要

In this paper, for the first time, we present a computational study on electrical characteristics of field effect tunneling transistors based on a vertical graphene-WS_2 heterostructure and vertical graphene nanoribbon (GNR)-WS_2 heterostructure (VTGNRFET). Our model uses the nonequilibrium Green's function formalism along with an atomistic tight binding (TB) method. The TB parameters are extracted by fitting the bandstructure to first principles results. We show that, due to the advantage of switching between tunneling and thermionic transport regimes, an improvement can be achieved in the electrical characteristics of the device. We find that the increase of the number of WS_2 layers enhances the on/off conductance ratio but degrades the intrinsic gate-delay time. The results indicate that the on/off conductance ratio of VTGNRFET increases with decreasing the GNR width.