Stability of the (InAs)1/(GaAs)1monolayer superlattice

Abstract

A first-principles total-energy pseudopotential calculation has been performed for the (001) (InAs${)}_1$/(GaAs${)}_1$ monolayer superlattice. It is shown that bulk (InAs${)}_1$/(GaAs${)}_1$ is thermodynamically unstable with respect to disproportionation into zinc-blende constituents. This instability is attributed to the unfavorable charge transfer from the GaAs layers to the InAs layers by estimating the strain-related and chemical contributions to the superlattice formation energy. It is found that epitaxial (InAs${)}_1$/(GaAs${)}_1$ grown on InAs, InP, or GaAs substrate is much less unstable than bulk (InAs${)}_1$/(GaAs${)}_1$, since the strain-related contribution becomes negative due to the epitaxial constraints. A simple criterion for the direction of charge transfer in monolayer superlattices is also proposed.