Optical, electrical and solid state properties of nano crystalline zinc sulphide thin films for device applications

Abstract

Semiconducting Zinc Sulphide (ZnS) thin films were deposited on glass substrate using relatively simple Chemical Bath Deposition (CBD) technique. Nano crystalline ZnS thin films were fabricated in the study. Optical characterization of the films showed that the materials are transparent to visible light, opaque to ultraviolet radiation and near infra red radiation. The electrical conductivity decreases as the energy increases while the optical conductivity increases gradually over an energy range, and then sharply afterward. The XRD pattern showed that the deposited ZnS had distinct peaks at 31.59, 32.21, 44.76 and 46.73^o respectively with 101, 110 and 111 preferred orientations. The energy band gap of ZnS film was found to be between 3.20–3.70eV with a direct band gap transition. These properties make ZnS thin films find useful applications as cover plates for solar energy panels and materials in the fabrication of semiconductor devices. In addition, the films were found to exhibit switching potentials.

Keywords: Electrical, Optical, Solid state properties, ZnS