Structural characterization of thin films based on II-VI ternary compounds deposited by evaporation

The studies revealed that In-rich ZnxIn1−xSe films and Te-rich CdSxTe1−x films grow with hexagonal structure; however, their structure is changed to cubic when they become Zn-rich and Te-rich, respectively. On the contrary, the ZnxIn1−xSe films grow with cubic structure, independently of its chemical composition. It was also found that the variation of the chemical composition leads to a significant variation of the optical gap Eg, which was determined by extrapolation of the curve (αhν)2 vs. hν, assuming that, for this type of compounds, the relation αhν = A(hν − Eg)1/2 is valid. It was observed, in the three type of compounds studied, that their Eg values increase with the decreasing of the lattice constant, which in turn varies according to Vegard's Law. Comparing the lattice parameters of the ZnSxSe1−x and ZnxIn1−xSe compounds, with those reported in the literature for Cu(In1−x,Gax)Se2 thin films, helpful information was found to achieve a good lattice match between the studied II-VI compounds and the CIGS film.