New Model for the Alloy(GaAs)1−xGe2x

We show that a previous model for ${\left(\mathrm{GaAs}\right)}_{1-x}{\mathrm{Ge}}_{2x}$, when more accurately analyzed, does not fit the observed composition dependence of the direct energy gap. A simple model for the lattice disorder is proposed. This model fits the composition dependence of the gap with no adjustable parameters. Our results show that antisite disorder and the transition from zinc-blende to diamond symmetry have no significant influence on the energy gap of this material.