Elimination of negative differential conductance in an asymmetric molecular transistor by an ac voltage

The authors analyze resonant tunneling subject to a nonadiabatic time-dependent bias voltage through an asymmetric single molecular quantum dot with coupling between the electronic and vibrational degrees of freedom using a Tien-Gordon-type rate equation. The results clearly exhibit the appearance of photon-assisted satellites in the current-voltage characteristics and the elimination of hot-phonon-induced negative differential conductance with increasing ac driving amplitude for an asymmetric system. This can be ascribed to an ac-induced suppression of unequilibrated (hot) phonons in an asymmetric system. (c) 2007 American Institute of Physics.