Au-Si-Au结点电子输运性质的第一性原理计算

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

采用密度泛函理论和非平衡格林函数相结合的方法对Au(100)-Si-Au(100)系统左侧对顶位、右侧对空位的纳米结点的电子输运性质进行了理论模拟计算,结果得到纳米结点的电导随电极距离(dz)增大而减小.在dz=9.72时,结点的结合能最低,结构最稳定,此时电导为1.227G0(G0=2e2/h),其电子输运通道主要是Si原子的px,py和pz轨道电子形成的最高占居轨道共振峰;在外偏压下,电流-电压曲线表现出线性特征;随着外加正负电压的增大,电导略有减小,且表现出不对称性的变化.

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 dz = 9.72 ,the structure of junctions is the most stable and the conductance is 1.227G0（G0 = 2e2/h）,which is contributed by the px,py and pz 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.