Simulation of gate-controlled Coulomb blockades in carbon nanotubes

The electronic transport properties of several nanotubes that are sandwiched between two metallic electrodes and modulated by a gate electrode are studied by a semiclassical approach based on the charging energies and electronic structures determined using ab initio density functional theory. The calculated conductance as a function of the bias and gate voltages shows how the bias and gate voltages control the electronic contribution to the electrical transport in nanotubes. Coulomb blockades and conducting resonances are revealed, and the conductivity of the nanotubes can be judged accordingly. The adjustments of both bias and gate voltages at room temperature can result in various interesting I-V characteristics, including the variable threshold bias voltage and plateau regions of the current, thus providing insight into the design of molecular devices with a variety of logical functions. (C) 2004 American Institute of Physics.