First-principles investigation on bonding formation and electronic structure of metal-graphene contacts

Metal-graphene contacts play a critical role in graphene-based electronics. It is found through first-principles calculation of contacts between graphene and 12 different metals that there exist two types of contacts depending on the strength of interaction between d-orbitals in metals and pz-orbitals in graphene. Fermi level shift in the contacted graphene from the freestanding one is investigated, and the electronic structure and electrostatic potential are calculated. The carrier transport through these contacts is calculated using the extended Hückel theory-based non-equilibrium Green’s function formalism, and one type of contact is shown to have less contact resistance than the other.