MESOSCOPIC TRANSPORT THROUGH A QUANTUM DOT–CARBON NANOTUBE SYSTEM IN AN APPLIED MICROWAVE FIELD

Abstract

The coherent transport through a quantum-dot (QD) coupled with single-wall carbon nanotubes (SWCNs) is investigated by employing the nonequilibrium Green's function (NGF) technique. An external microwave field is applied to the central QD to induce side-bands in addition to the energy levels of the QD. The SWCNs act as quantum wires which open quantum channels for electron to transport through. The novel behaviors are obtained in differential conductance and tunneling current, which are strongly associated with the density of states (DOS) of leads. The hybrid system with a QD coupled to normal metal and SWCN is also investigated as a comparison. The armchair SWCN lead provides rich tunneling channels compared with that of a metal lead. The I–V characteristics is calculated to exhibit stair-like structures which correspond to the resonant peaks of differential conductance versus source–drain bias. The current resonance with the gate voltage is shown to exhibit the photon-assisted tunneling.