Conductance-Voltage Characteristics of Single Molecule Junction: in Resonant Tunneling Regime

Abstract

Electronic transport characteristics through a single molecule junction are investigated by using the Keldysh non equilibrium Green function (NEGF) model. The model consists of a molecular bridge (represented by a molecular orbital) attached with two free electron reservoirs (represents two metallic leads) and it is coupled with a vibrational degree of freedom (represents a molecular vibrational mode). The behavior of the electronic transfer through the molecular junction becomes more clearly visible by studying of the conductance-voltage characteristics. The numerical calculations are done based on this model to study the changes in conductance behavior through a single molecule junction in the resonant tunneling regime. According to our results, the conductance-voltage characteristics are influenced by (I) the electron-vibration interaction, (II) the molecular bridge-leads coupling strength, (III) the junction temperature, and (IV) the molecular vibrational mode energy. We conclude that the previous parameters have a significant role in determination of the electron conduction through the single-molecule junctions. Especially, the conductance is very sensitive to the molecular bridge-leads coupling strength and the junction temperature. These features provide important information about the study of the electronic transport phenomena in molecular junctions.

Keywords

• molecular junction
• nonequilibrium green function theory
• electronic transport
• conductance
• electron
• vibration coupling