Dopant-Concentration Dependent Optical and Structural Properties of Cu-Doped Zns Thin Films

In this paper, using the chemical bath deposition method and employing the suitable deposition temperature, internal doping of Cu^2+ ions into nanocrystalline ZnS thin films is reported. X-ray diffraction analysis (XRD) was used to evaluate the structure of the films, which consists of sub-7 nm crystallites of the cubic ZnS. FE-SEM images indicated that the surface morphology of the Cu-doped ZnS films is strongly dependent on dopant level. The influence of the Cu^2+ ions concentration on optical and specially photoluminescence properties of the Cu:ZnS thin films have been investigated and discussed. Defect-free emission spectra at low deposition temperatures and the appearance of the dopant-related emission peak at higher temperatures demonstrate that this method is an effective strategy for chemical deposition of the Cu-doped ZnS nanocrystals on glass substrates. Furthermore, the concentration quenching effect on photoluminescence intensity has been observed which can be related to non-radiative transitions between electronic energy levels of the neighboring Cu^2+ ions in the ZnS host lattice.