Chemical bath pH influence on the structural, morphological and optical properties of zinc sulphide thin film prepared from acidic baths

Abstract

Zinc sulphide (ZnS) thin films were prepared on glass substrate by using solution growth method from acidic chemical bath. The effect of bath pH on the physical and chemical properties of ZnS thin films were established well. The synthesized thin films were characterized by different techniques to study how bath pH affects the nature of the ZnS thin films. The XRD study established that the prepared ZnS thin films had a cubic crystal structure. The XRD results further showed that the diffraction peaks around 28.7° and 48.1° enhanced as the bath pH increased. The SEM study confirmed that the bath pH play significant role on the nature of the surface morphology of ZnS thin film deposited in acidic chemical bath. The EDS study confirmed the presence of the constituent elements Zn and S. This measurement also shows that the prepared ZnS thin films were in a good stoichiometric ratio (Zn/S). The optical band gap of the prepared thin films found in the range of 3.24 eV to 3.89 eV as the bath pH decreased from 4.86 to 4. Irrespective of bath pH, all the deposited ZnS thin films exhibited a strong PL emission in red region, however, the intensity of the PL emissions were varied with bath pH.