The band gap bowing of CdS_xTe_1−x alloys beyond the virtual crystal approximation

The effect of alloy disorder on direct and indirect band gap energies in CdS_xTe_1−x semiconducting alloys has been investigated. The calculations are performed using a pseudopotential approach within the virtual crystal approximation (VCA). In the simplest approximation based on the VCA, the fundamental band gap bowing of CdS_xTe_1−x is found to be in disagreement with that of the experiment. The value of this bowing is highly improved by taking into account the compositional disorder effect (i.e. going beyond the VCA).