SYSTEMATIC STUDIES OF THE ELECTRONIC TRANSPORT IN REALISTIC EDGE DISORDERD GRAPHENE NANORIBBONS

Abstract

We have made systematic studies of the electronic transport in realistic edge disordered graphene nanoribbons with, both zigzag and armchair edges. Three different defect topologies were examined. The stone-wales mechanism reconstructs zigzag graphene nanoribbon edges into alternating pentagon-heptagon pairs, while in a armchair it causes two separate armrest hexagons to merge into adjacent heptagons. In realistic defect topologies we first relaxed the atomic geometries using density functional theory. In tight binding parameters for the relaxed geometries from the standard quantum chemical parametization of the extended Huckel model was considered. The calculated conductances revealed strong backward scattering and electron hole symmetry depending upon the edge and defect. An additions defect induced band whose wave function was poorly matched to the propagating states of the pristine ribbon. We found that the electron-electron interactions gave rise to charge redistribution towards the edges of the ribbons when gating shifted the ribbon Fermi energy away from the Dirac point.