First-principles calculations of the electronic transport in Au-Si-Au junctions

The transport property of silicon sandwiched between Au (100) and Au (100) is investigated with a combination of density functional theory and non-equilibrium Green's function method. It is found that the conductance decreases with distance increasing. When d(z) = 9.72 angstrom, the structure of junctions is the most stable and the conductance is 1.227G(0) (G(0) = 2e(2)/h), which is contributed by the p(x), p(y) and it, electron orbits of silicon atom. The I-V curve of junctions shows linear characteristics under the external bias vottage. With the increase of an external positive and negative voltage, the conductance decreases slightly, and presents the asymmetry change.