Composition-dependent band gap in ZnSxSe1-x:: a combined experimental and theoretical study

The energetic, structural and electronic properties of ZnS-ZnSe mixed phases have been investigated by a combined experimental and theoretical approach. The crystallographic parameters of the mixed crystals have been measured by X-ray powder methods. The band gaps are determined from optical spectroscopy. The results of quantum chemical calculations at density functional level are compared to the experimental data. The solid solutions were modeled with supercells of varying S and Se content. Both experimentally and theoretically, an almost linear dependence of the lattice constant and cohesion energy on composition was found. The influence of anion distribution and local relaxation on the calculated electronic structure was investigated. The optical band gap shows a non-linear dependence on the S content. (c) 2005 Elsevier SAS. All rights reserved.