Variable electronic transport properties of double carbon-nanotube junctions via substitutional Fe, Co, and Mn atom doping

Abstract

Electronic and transport properties of carbon-nanotube (CNT) hybrid junction CNT(3,3)/CNT(6,0)/CNT(3,3) are investigated and compared with substitutionally doped junction with transition metal atoms, iron, cobalt, and manganese; using density functional theory combined with non-equilibrium Green's function formalism. Transmission coefficient and current–voltage (I–V) characteristics are calculated for all configurations. The results indicate a smooth increase of current with voltage in pristine junction up to 0.75 V while in the case of higher voltages, the increase accelerates significantly and the conductance for the voltages between 1 and 1.5 becomes almost constant, about 40μA V. The replacement of carbon atoms with Fe, Co, and Mn in the scattering region causes rather substantial reduction of the transmission and conductance of the hybrid junction. It causes the current to reduce nearly 25% at the voltage of 1.5 V compared to the pristine one. It also appears that, there is no serious difference in the I–V characteristics for different impurity atoms, except some deviation in manganese conductance from the other two impurities’ curves. These results can be useful for future CNTs based nano-electronic applications.