First-principles study of the electron transport behavior of short graphene nanoribbon

The electron transport behavior of a short graphene nanoribbon sandwiched between two gold(111) electrodes is investigated using density functional theory calculations and nonequilibrium Green's function technique. The calculated current-voltage characteristic of the graphene nanoribbon junction shows an obvious negative differential resistance (NDR) phenomenon. The mechanism of this NDR behavior of graphene nanoribbon is discussed in terms of the evolution of the molecular energy levels, the spatial distribution of frontier molecular orbitals, and the electron transmission spectra under various applied biases. It is found that the changes of the spatial distribution of molecular orbitals near Fermi level with the applied bias lead to such NDR behavior.