Effects of Contact Geometry on the Transport Properties of a Silicon Atom

Contact geometry and electronic transport properties of a silicon atom sandwiched between Au electrodes in three different anchoring configurations are investigated by using the density functional theory combined with the non?equilibrium Green function method. We simulate the nanoscale junction breaking process and calculate the corresponding cohesion energy, obtain the equilibrium conductance and the projected density of states of junctions in an optimal postion. We also calculate the conductance and the current of junctions at the equilibrium position under small bias voltage. It is found that all junctions have large conductance and show a linear I–V relationship, but the current and conductance of a hollow-hollow configuration is always the biggest under the voltage range of -1.2 V～1.2V. The calculated results proved that the coupling morphology of a silicon atom connected with electrodes has an important effect on the electronic transport properties of the nanoscale junction.