Influence of disorder effects on Cd1-xZnxTe optical properties

In this work we proposed a theoretical expression of the band gap dependence with Zn concentration in Cd(1-x)n(x)Te alloys. We used the modified virtual crystal approximation and the tight-binding parameters, which incorporate compositional disorder as an effective potential. The fitting parameters used were the disorder parameter p(c) for the alloy and the tight-binding parameters of each binary compound at room temperature. We found that the theoretical model must include disorder effects in order to describe the bowing of the experimental dependence. The theoretical expression is in good agreement with the quadratic function of the energy gap obtained from the fitting of photoreflectance measurements and from values reported by other authors. The experimental analysis was done on polycrystalline thin films grown over glass substrates by rf sputtering technique.