Tunneling transport in STM-tip-nanotube-substrate systems

In this paper, we considered a single-wall carbon nanotube deposited on a s ubstrate and probed by a scanning probe. We calculated the current and diff erential conductance dI/dV versus the bias voltage V in this system. We fou nd that currents through nanotubes become saturated in high voltages. This result shows the one-dimensional characteristic of carbon nanotubes. Our re sults are consistent with experiments which were carried out in low bias vo ltage regime and can be tested easily by experiments in higher bias voltage regime.