Optical and Morphological Properties of Electrodeposited Thin Films of ZnS

Abstract

Zinc sulphide (ZnS) thin films were grown on glass/fluorine-doped tin oxide (FTO) substrates using the simple and inexpensive electrodeposition technique. The deposition electrolytic bath was prepared from aqueous acidic solution of ZnSO4 and (NH4)2S2O3. The work was carried out to investigate the optical and morphological properties of ZnS layers. The deposition temperature and the pH values were respectively 30°C and 1.50. It was observed that optical properties vary with variation in growth voltage. It was observed that bandgap decrease with increase in growth voltage since the higher the growth voltage, the higher the current density. As the deposition temperature in increased, the bandgap is seen to decrease. After annealing, the bandgaps are seen to increase and the absorption edges can be seen to have smoothened out. Increase in annealing temperature play a significant role in achieving desired results especially when it is meant for device application. As expected, the layer thickness is seen to increase with increase in deposition temperature.