The Influence of Heat Treatment on the Optical Parameters of Spray-Deposited CdS:In Thin Films

Cadmium sulfide is an important material for solar cells and optoelectronic devices. For the development of these technologies, there is a need for comprehensive optical characterization of this material. Doping with indium improves the bandgap energy and other optical parameters of CdS. In this study, polycrystalline indium doped cadmium sulfide thin films (CdS:In) are produced by the spray pyrolysis technique on glass substrates. The films were annealed in nitrogen atmosphere, and the influence of heat treatment on the optical parameters was investigated. Transmittance was measured at room temperature and used to deduce absorption coefficient, bandgap energy, extinction coefficient, and refractive index before and after annealing in nitrogen atmosphere. It is found that all of these parameters are influenced by such heat treatment.