Topology effects of interface and gate voltage on electrical transport through the CNT/C60/CNT junction using the Green's function method

In this work, we investigate electron transport across a carbon molecular junction consisting of a C-60 molecule attached to two semi-infinite metallic open-end CNT leads in the coherent regime. Here, we put emphasis on topology of the molecular-electrode interface and gate voltage, and obtain the electrical transmission through the CNT/C-60/CNT structure, using the Green's function method in the framework of a nearest neighbor tight-binding approximation. To this end, three different ways of coupling C-60 fullerene through one, five, and six carbon atoms to the CNT-leads in the direction of the longitudinal axis of the tube have been considered. Also, the current-voltage characteristic is calculated in the Landauer-Buttiker formalism at room temperature. It is shown that the number of contact points between the electrodes and the molecule can play an important role in the electrical transport. Also, the bond dimerization and a gate voltage shift the molecular levels, where by adjusting the related parameters the electron conduction can be controlled. Our results show that the proposed structure gives rise to the resonance states and quasi-bound states (Fano resonances) close to -2.63 eV. These antiresonance states are related to the active region and independent from the coupling strength between the device and the leads. The numerical results may serve as important components of nanocircuits. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3602994]