I–V curves of carbon nanotubes with copper contacts using non-equilibrium Greenʹs function method

Using the non-equilibrium Greenʹs function method together with the density-functional theory, the interfaces of carbon nanotubes (CNTs) with Cu electrodes are modeled and the associated I/V curves are evaluated. It is found that the geometry of the interface and electronic transport characteristics are dependent significantly on the diameter of the CNTs. In comparison with the pristine CNT electrode system, the conductance change for the Cu/CNT/Cu system is more sensitive for large diameter CNTs whether the CNT is metallic or semiconductive. The results indicate that the origin is the Cu contacts, which change the electronic structures and the hybridization type of the CNTs due to the C-2pπ and Cu-4s orbital overlaps.