Composition and temperature dependence of electron band structure in ZnSe1−xSx

Using the empirical pseudo-potential method combined with the improved virtual crystal approximation where compositional disorder is included as an effective potential, we report on the results of composition and temperature-dependent optical band gaps, of the ZnSe1−xSx (0≤x≤1) type alloys. The obtained results compare reasonably well with the available experimental data. The fundamental band gap is found to vary non-linearly with composition, showing a bowing. Similar bowing is also observed from the temperature-dependent fundamental band gap. This bowing decreases with increasing temperature over the range 0–200 K, but it increases gradually on going from 200 to 300 K. The expression Eg(x,T)=2.828+0.45x+0.53x2+T(−3.45x2+3.22x−3.88)×10−4 was obtained from the data can be used to obtain the energy gap as a function of x and T over a large range of these variables