“金属-Si原子链-金属”纳米结点电子输运性质的计算

Calculation on the Electron Transport Properties of Metal-Silicon Atomic Chain-Metal's Nanoscale Junctions

运用密度泛函理论结合非平衡格林函数，以5个Si原子构成的直线链，及其与2个半无限长Au（100）-3×3电极相连接构成的金属-原子链-金属“三明治”模型为研究对象，对该结构的纳米级结点的电子输运进行了计算．结果表明，在两极距离d2=1．95～2．39nm的拉伸过程中，结点电导值有数量级的变化．当dz=2．03nm时，结点的结合能最小（△E=-5．43eV），结点结构最稳定，原子链内部Si-Si键长平均值为0．216nm，此时结点的电导为0．44Go（G。=2e^2／h）．Si原子的Po与Py轨道电子形成“键，构成了电子经过结点的主要传输通道；随着正负外偏电压的增大，电导减小，且成对称变化，其I-U曲线表现出非线性特征。

Taking the 5 silicon-atom-composed linear chain and the Sandwich type of Metal-Silicon Atomic Chain-Metal＇ model formed by the linear chain＇s connection with the two and a half unlimited Au （100）- 3 × 3 electrode pole as the object of study, this article calculates its nanometer and the junction electronic transport with density functional theory combined with the Non-Equilibrium Green Function. The result shows that during the pulling course with the distance between dz = 1. 95-2. 39 nm, Node conductance value changes in the order of magnitude, and the binding energy of the node comes to its minimum （△E= -5.43 eV） and in the most stable structure when dz = 2.03 nm, and the average chain length of Si-Si Chain inside atom is 0. 216 nm, and the electronic conductivity of the node is 0.44 Go （Go = 2e2/h）. The px and py Silicon Atom orbital electron bone forms the main transmission channel through which the electron pass the node; The electronic conductivity decreases and changes symmetrically as the positive and negetive bias increase, the I-U curve shows up the nonlinearity.