Nonlinear conductance in finite-length armchair single-wall carbon nanotubes with one single impurity

We investigate theoretically the nonlinear quantum conductance of finite single-wall carbon nanotubes (SWCNTs) due to the presence of a single impurity. To take the length of the tube into account and retain the periodicity of the SWCNT along its axis, a particle-in-a-box model is employed. The dependence of the differential conductance on the gate voltage as well as its sensitive dependence on the position of the possible impurity in the tube is studied. Results suggest a promising method for spectroscopy of electronic energy levels in a SWCNT