β-SiC(001)-(2×1)表面结构的第一性原理研究

利用缀加平面波加局域轨道(APW+LO)的第一性原理方法计算了β-SiC(001)-(2×1)表面的原子及电子结构. 原子结构的计算结果表明，与Si(001)-(2×1) 表面的非对称性Si二聚体模型不同，β-SiC(001)-(2×1)表面为对称性的Si二聚体模型，其二聚体的Si原子间键长也较大，为0.269nm. 电子结构的计算结果表明，在费米能级处有明显的态密度，因此β-SiC(001)-(2×1)表面呈金属性. 在带隙附近存在四个表面态带,其中的两个占有表面态带已由价带的同步辐射光电子能谱实验得到证实.关键词：碳化硅缀加平面波加局域轨道方法原子结构电子结构

First principle study on β-SiC(001)-(2×1) surface structure

We calculate the atomic and electronic structure of β-SiC(001)-(2×1) using augmented plane wave and local orbital (APW+LO) method. The calculated results show that the atomic structure of β-SiC(001)-(2×1) surface can be described by symmetrical Si dimmer model, which is different from the asymmetrical Si dimmer model of Si(001)-(2×1) surface. The bond length of Si dimmer of β-SiC(001)-(2×1) surface is 0.269 nm, which is larger than that of Si(001)-(2×1) surface. The calculated results of electronic structure show that a prominent density of states exists at the Fermi level, so β-SiC(001)-(2×1) surface has the characteristics of metal. There are four surface state bands in the gap. Among them, two occupied surface state bands have been confirmed by valence band spectra of synchrotron radiation photoelectron spectroscopy.