Optically induced current in molecular conduction nanojunctions with semiconductor contacts

We propose a new approach to coherent control of transport via molecular junctions, which bypasses several of the hurdles to experimental realization of optically manipulated nanoelectronics noted in the previous literature. The method is based on the application of intrinsic semiconductor contacts and optical frequencies below the semiconductor bandgap. To explore the coherently controlled electronic dynamics, we introduce a density matrix formalism that accounts for both the discrete molecular state and the semiconductor quasicontinua within a single master equation and offers analytically soluble limits for a single and two-site molecular bridge. Our analytical theory predicts a new phenomenon, referred to as coherent destruction of induced tunnelling, which extends the phenomenon of coherent destruction of tunnelling frequently discussed in the previous literature. Our results illustrate the potential of semiconductor contacts in coherent control of photocurrent.