Effect of Disorders in Graphene Nanoribbon Field-Effect Transistors

Recent progress on the graphene and graphene nanoribbon (GNR) has provoked strong interests in GNR field-effect transistors (FETs) for future digital and analog nanoelectronics applications. In this work, device characteristics of GNRFETs are calculated by solving the non-equilibrium Green's function (NEGF) transport equation in an atomistic p$_{Z}$ orbital basis set self-consistently with three-dimensional (3D) Poisson equation. The effects of a lattice vacancy, ionized impurity, and edge roughness on transistor performance and characteristics are examined by the atomistic simulations. We show that even a single disorder can have a significant effect on the device characteristics of GNRFETs due to the atomically thin and nanometer-wide channel geometry. For example, a single lattice vacancy can affect the on-current of a GNRFET by 40{\%}. Localized states in the GNR band gap energy range can be induced by the disorders, which affect quantum transport and self-consistent electrostatics. Significant variations between devices are expected due to disorders, but the GNRFETs still switch in the presence of moderate amount of disorders.