In this paper, we studied the electronic conductance and energy gap of a graphene nano-ribbon which is connected to two semi-infinite atomic chains by the atoms located in the opposite sides of nano-ribbon. The numerical calculations were performed using the Green’s function method in the nearest neighbor approximation of tight-binding approach. The conductance curves plotted with respect to incoming electron energy show that for a zigzag graphene nano-ribbon with one benzene ring in its width, there is no gap in the energy band spectra of the system, while for the armchair case, an energy gap always exists around the Fermi energy and its value depends on the size of the nano-ribbon. The results show that the behavior of the graphene nano-ribbons conductance strongly depends on that how and where the leads connect to the nano-ribbon and on the contacts qualities.

Keywords: Nano-ribbon, Electronic Conductance, Energy gap, Green’s function, tight-binding

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