Theoretical Investigation on the Contact Resistance Between the Thiol Anchoring Group and the Gold Electrodes

The electronic transportation of a series of gold-sulfur atomic chains with different length was investigated theoretically by using density functional theory combined with nonequilibrium Green's function method. The result shows that the conductance of gold wires with sulfur linking is larger than that of the pure gold atomic chains. In addition, the conductance keeps almost constant and does not decrease exponentially with the molecular chain length, which is different from the organic molecular wire. The results indicate that the sulfur group is well coupled to the gold electrode. As the molecule is anchored to the gold electrodes via the sulfur group in the junction, the contact resistance between the sulfur and gold electrode is small, and the junction resistance Is mainly contributed by the molecule.