Studies on electronic structures and optical properties of ZnS:Er based on the first principles

The electronic structures and optical properties of ZnS and ZnS:Er have been studied using the first-principles plane-wave pseudopotential method. The calculations show that the bandgap of ZnS:Er becomes narrow in the case of Er ³⁺-doping and a new intermediate band between valence band and conduction band is presented. Moreover, with the Er ³⁺ concentration increasing, the insulativity of ZnS:Er presents a decreasing trend, and the absorption spectra exhibit a red-shift, which are in agreement with the previous experimental results.