Simulation of carbon nanotube field-effect devices

Ab initio quantum mechanical numerical simulations have been used to study electronic transport in nanoscale electronic devices. We have developed a new code based on self-consistent density-functional tight-binding (DFTB) method and non-equilibrium Green´s function (NEGF) formalism. Using this approach, we investigate the coherent transport properties of a long semiconducting CNT when the source-drain current is modulated by a coaxial gate. Exact boundary conditions for the electrostatic potential in the coaxial gate geometry are taken into account solving in real space a 3D Poisson equation. Results stress the importance of a good electrostatic-design of the gate contact to obtain the same field-effect modulation we have in conventional planar MOSFET.