NEGF simulations of metal contacts for graphene nanoribbon based device

For nanoscale electronic devices, the precise atomic structure of the metal contact plays a significant role on the performance of the device. We use an accurate, DFT-based non-equilibrium Green’s function method with variationally-optimized localized orbitals to study contacts between different metals and graphene and/or graphene nanoribbons (GNRs). For on-top metal contacts not chemically bound to graphene, we have found that Ti contacts have lower resistance than other metals, such as Au, Ca, Ir, Pt, and Sr. We will discuss channel length effects on the off-state current and the required minimum channel and metal-graphene contact lengths for applications. Other contact structures (side contacts with chemical bonds) will also be discussed.