Accurate ab initio pseudopotential calculations were performed for the structural and electronic properties of ZnSe/GaAs(001) heterostructures with interface configurations accounting for charge neutrality prescriptions. In addition to the simplest configurations with atomic interdiffusion some configurations were also considered which were characterized by As depletion and cation vacancies, motivated by the recent successful growth of ZnSe/GaAs pseudomorphic structures with minimum stacking fault density characterized by the presence of a defected (Zn,Ga)Se alloy in the interface region. It was found that—under particular thermodynamic conditions—some defective configurations were favoured with respect to non-defective ones with simple anion or cation mixing, and that the calculated band offsets for some defective structures were compatible with those measured. Although it was not possible to extract information concerning the precise interface composition and vacancy concentration, the results supported the experimental indication of (Zn,Ga)Se defected compounds in high-quality ZnSe/GaAs(001) heterojunctions with a low native stacking-fault density. The range of measured band offset suggested that different atoms at interfaces were rearranged, with the possible presence of vacancies, in such a way that not only local charges but also ionic dipoles vanished.

ZnSe/GaAs(001) Heterostructures with Defected Interfaces - Structural, Thermodynamic and Electronic Properties. A.Stroppa, M.Peressi: Physical Review B, 2005, 72[24], 245304 (10pp)