On the role of disorder on graphene and graphene nanoribbon-based vertical tunneling transistors

Abstract

In this work, the characteristics of vertical tunneling field-effect transistors based on graphene (VTGFET) and graphene nanoribbon heterostructure (VTGNRFET) in the presence of disorder are theoretically investigated. An statistical analysis based on an atomistic tight-binding model for the electronic bandstructure along with the non-equilibrium Green's function formalism are employed. We study the dependence of the averaged density of states, transmission probability, on- and off-state conductances, on/off conductance ratio, and transfer characteristics on the substrate induced potential fluctuations and vacancies. In addition, the variabilities of the device characteristics due to the presence of disorder are evaluated. It can be inferred from the results that while introducing vacancies cause a relatively modest suppression of the transmission probability, potential fluctuations lead to the significant increase of transmission probability and conductance of the device. Moreover, the results show that the transport properties of VTGFET are more robust against disorder compared to VTGNRFET.

Exclusive sub-lattices for extended and localized states in graphene ribbons: their role in Klein tunneling, disorder and magnetic field effects

“…Finally, we study impurity effects (disorder) in the system, figure 5. The effects of local impurities [42,43] are included in our system by considering a randomly distributed potential U in the diagonal elements of the Hamiltonian H of equation (1). The disorder model used here consists in choosing randomly N transverse chains with n impurities in each chain.…”