Length dependence of effect of electrode contact on transport properties of semiconducting carbon nanotubes

We investigate the transport properties of finite-size semiconducting carbon nanotubes connected to metallic electrodes by first-principles calculations. The electronic states are calculated using a numerical atomic orbital basis set in the framework of density functional theory, and the conductance is calculated using the Green’s function method. We show the transmission spectra of carbon nanotubes connected to aluminum electrodes and reveal the exponential decay of conductance with increasing length of nanotubes.