Si中D3d对称性态密度分布和缺陷对电子结构

本文考虑了晶体中总的电子态密度在低对称性下用点群不可约表示基函数分解的问题,并给出了Si中用D_3d群不可约表示基函数分解最近邻两原子总态密度的计算结果。结合在位势近似Koster-Slater格林函数方法,文中将计算结果用于Si中双空位和硫属元素杂质对(S₂⁰,Se₂⁰和Te₂⁰)缺陷态电子结构的讨论。讨论得到的结果是:与点缺陷和缺陷对的深缺陷态对称性相匹配的部分态密度的分布是相似的;在态密度对缺陷能级的驱赶作用下,S₂⁰等的A^s能级在A^s能级之上,双空位的E_g能级在E_u能级之上,这种情况与通常双原子分子成反键能级位置完全相反;所讨论的缺陷对的波函数在Bloch空间的分布情况与对应的点缺陷类似。关键词：

D3d SYMMETRIC LOCAL SPECTRAL DENSITIES AND THE ELECTRONIC STRUCTURES OF SUBSTITUTIONAL PAIRS IN Si

By using the irreducible representation basis functions of the point group whose symmetry is lower than Td, a decomposition of the total density of states is considered. The calculation-results are obtained for the D_3d point group in Si. Combining with the Koster-Slater Green's function method and on site approximation, the calculation results are used to analyse the electronic structures of the divacancy and the chalcogenide paris (S₂⁰, Se₂⁰, Te₂⁰) in Si. Some interesting results are obtained as follows; The distribution of the local spectral densities closely related to the deep states in forbidden band is similar for point and pair defects. Under the expellant action caused by the local spectral density, the symmetrical A₁₀^s (chalcogenide pairs) and E_g, (divacancy) states are higher than the antisymmetrical A_2u^s (chalcogenide pairs) and E_u, (divacancy) states. The distribution of the deep state wavefuctions in Bloch space is also, similar for point and pair defects.