摘要
在紧束缚近似基础上,本文采用Recursion方法首次计算了含有杂质和空位的短周期AlAs/GaAs超晶格电子结构。局域态密度和分波态密度的计算结果清楚地反映了少量无序杂质和空位在AlAs/GsAs中的局部细节以及对材料本身电学性质的影响。在具有点缺陷(杂质或空位)的AlAs/GaAs材料能隙中将出现新能级,本文计算了它们的位置。同时利用对原子价的讨论发现体内点缺陷周围存在一个电中心,而界面点缺陷产生一个局域电场,它将导致电荷分布的转移。比较了杂质和空位的影响,并进一步证明在所有情况下它们的作用是高度局域的。
Based on the tight-binding approximation (TBA), the electronic structures of short-periodAlAs/GaAs superlattices with impurities and vacancies are calculated by Recursion method forthe first time.The calculated results of local-and partial-density of states clearly show the localenvironment of the relatively small amounts of disordered impurities and vacancies in AlAs/GaAs and their influence on the electronic properties of these materials. The positions of newstates appeared in the band gap of AlAs/GaAs structures with different point defects are calculated.By the aid of the discussion of atom valence, the authors find that there are an electroniccenter around a point defect in the bulk and a local field across the interface with an impurityor a vacancy which will induce a slight shift of the charge density. Comparison of the influencebetween impurity and vacancy on the pure superlattices is given. Furthermore, the authors confirmthat the affect of a disordered point defect is highly localized in all cases.
基金
国家教委博士点基金
关键词
AlAs/GaAs
超晶格
电子结构
杂质
AlAs/GaAs Superlattice
Electron structure
Local field
Electronic center around an impurity or a vacancy
