Length- and temperature-dependent crossover of charge transport across molecular junctions
Journal
Physical Review B
Journal Volume
84
Journal Issue
7
Date Issued
2011
Author(s)
URI
Abstract
We study the electronic transport in a molecular junction, in which each unit is coupled to a local phonon bath, using the nonequilibrium Green's function method. We observe that the conductance oscillates with the molecular chain length and that the oscillation period in odd-numbered chains depends strongly on the applied bias. This oscillatory behavior is smeared out at the bias voltage near the phonon energy. For the phonon-free case, we find a crossover from tunneling to thermally activated transport as the length of the molecule increases. In the presence of the electron-phonon interaction, the transport is thermally driven and a crossover from thermally suppressed conduction to assisted conduction is observed.
Type
journal article