Interaction of Localized Electronic States with the Conduction Band: Band Anticrossing in II-VI Semiconductor Ternaries

We report a strongly nonlinear pressure dependence of the band gaps and large downward shifts of the conduction band edges as functions of composition in ZnS xTe (1-x) and ZnSe (y)Te (1-y) alloys. The dependencies are explained by an interaction between localized A1 symmetry states of S or Se atoms and the extended states of the ZnTe matrix. These results, combined with previous studies of III-N-V materials define a new, broad class of semiconductor alloys in which the introduction of highly electronegative atoms leads to dramatic modifications of the conduction band structure. The modifications are well described by the recently introduced band anticrossing model.