CO adsorption on a zigzag SiC nanotube: effects of concentration density and local torsion on transport

The electron transport properties of CO adsorbed SiC nanotubes as a function of concentration density and structural deformation have been characterized for the single-walled (7,0) zigzag model using a combined formalism of density-functional theory and nonequilibrium Green’s function. It is found that CO adsorption can significantly suppress the transmission spectrum of SiC nanotube for a wide range of energies. As the concentration increases, a density-dependent superimposed transport gap exists and widens the initial electronic band gap of SiC nanotube. Under the same applied bias voltage, the current through SiC nanotube decreases with the increasing CO concentrations. The local torsional deformation has no effect on this essential motif. However, the current in the locally twisted system is larger than that of the undeformed one. The transmission suppression and the current differences can be attributed to the response of the localized impurity state induced by CO adsorption to density and deformation. Our results show that SiC nanotube can be a promising gas sensor for CO detection.