Electronic transport through side-contacted graphene nanoribbons: effects of overlap,aspect ratio and orientation

Abstract

We numerically calculate the conductance and shot noise Fano factor of graphenenanoribbons (GNRs) side-contacted to metallic leads. A tight-binding model andLandauer’s formalism are used in combination with a modified recursion method forGreen’s functions. The interfaces are modeled as a contact region between aninfinite metallic electrode and a segment of the GNR put on top of it. The keyquestion to answer in this study is how the size and orientation of the GNR and theGNR/electrode interface area influence the transport properties. It turns out that ingeneral the transport characteristics depend strongly on overlap, meant as theratio between the electrode-supported GNR length and the unsupported one.Moreover, a speed of convergence (with the overlap length) depends on both thetransport direction and the aspect ratio of the GNR. It is shown that a shortoverlap interface is often, but not always, advantageous in nanoelectronics. Thesefindings reconcile some seemingly conflicting opinions reported in the literature.