lnfluence of Impurities and Vacancies on Electronic Properties of AlAs/GaAs Superlattices
杂质和空位对AlAs/GaAs超晶格电学性质的影响

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.