Cation variations at semiconductor interfaces: ZnSe(001)/GaAs(001) superlattices

We investigated the possibility that the interface energy in heteroepitaxial compound semiconductor systems can be characterized by a unique value. We suggest that the per-bond binding energy, which is associated with the strength of the chemical bonds that span the interface between the different compounds, is this desired value. We chose the ZnSe(001)/GaAs(001) system for this study because of its relatively small lattice mismatch. Three chemically different interfaces were studied: One containing only Ga–Se bonds, one containing only Zn–As bonds, and one with an equal [i.e., 50:50] mixture of these bonds. We employed first-principles density-functional theory electronic-structure calculations to obtain the structure and binding energy of the bonds and these interfaces, for a variety of unit cells in order to find the favored configurations under static lattice conditions. The destabilizing effect of an interfacial charge imbalance, and, one of the limitations of density-functional theory calculations in this circumstance are also discussed.

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