Electrical Property of Zigzag Graphene-Molecular Nanojunction

We have investigated the transport properties of a molecular nano-junction using density functional theory (DFT) combined with non-equilibrium Green's function (NEGF) technique. Our result demonstrate that, at small bias voltage the current conduction through the nano-junction is insignificant but when bias exceeds 1.8 V, current increases nonlinearly with the voltage. The transmission curve indicates that the current at different bias voltage depends on contribution from different frontier orbital and shed insight on the tunneling probability between frontier energy states of the scattering region and the electrodes. Partial density of states (PDOS) analysis gives the evidence that the energy states near the Fermi energy and away from the Fermi energy for both valence band (VB) and conduction band (CB) depends on bias voltage and the contribution of energy state increases with increasing bias voltage. Our study also confirms that, within the bias window the change in the energy states mainly appears in the valence band with increasing bias voltage.