Au掺杂硅纳米线的稳定性和电子结构

Stability and Electronic Structures of Au-Doped Silicon Nanowires

采用基于密度泛函理论的第一性原理的方法,对Au掺杂[100]方向氧钝化硅纳米线(SiNWs)不同位置的形成能、能带结构、态密度及磁性进行了计算,考虑了Au占据硅纳米线的替代、四面体间隙和六角形间隙的不同位置.结果表明:Au偏爱硅纳米线中心的替代位置.Au掺杂后的硅纳米线引入了杂质能级,禁带宽度变窄.对于Au替代掺杂,杂质能级主要来源于Au的d、p态和Si的p态,由于Au的d态和Si的p态的耦合,Au掺杂硅纳米线具有铁磁性.对于间隙掺杂,杂质能级主要求源于Au的s态,是非磁性的.另外,根据原子轨道和电子填充模型分析了其电子结构和磁性.

We calculated the formation energies, band structure, density of states, and magnetic properties of Au-doped hydrogen-passivated silicon nanowires （SiNWs） along the [100] direction at different positions by first-principles method based on density functional theory. We considered the substitutional positions, the interstitial positions with tetrahedral symmetry, and the interstitial positions with hexagonal symmetry. The results show.that Au preferentially occupies the center substitutional position of the silicon nanowire. The doping of Au into silicon nanowires introduces an impurity level near the Fermi level. The bandgap values were less than those of pure silicon nanowires. For the substitutionally doping of silicon nanowires the density of states near the Fermi level were mainly contributed to by the Au d and p orbitals and the Si p orbital. Ferromagnetic behavior of the substitutionally doped nanowire was observed upon coupling the Au d and Sip states. For the interstitial doping of silicon nanowires nonmagnetic behavior was predicted. In addition, we also interpret the electronic and magnetic properties in terms of a simple analysis based on the atomic orbitals and electron filling.