Effect of Concentration on the Structural and Optical Properties of ZnS Thin Films Deposited by the Spray Pyrolysis Technique

Zinc sulfide (ZnS) thin films were deposited on glass substrates using the spray pyrolysis technique (SPD) with different precursor concentrations (10-4 to 10-1M). The structural, morphological, compositional, and optical properties were investigated using X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), and UV-Vis spectroscopy. XRD results revealed a transformation from amorphous to crystalline cubic ZnS structure with increasing precursor concentration. FESEM and AFM analyses showed that higher concentrations produced smoother surfaces with smaller particle sizes. EDX confirmed improved stoichiometry at higher concentrations. The optical band gap decreased from 4.16 to 3.21 eV as concentration increased, indicating improved crystallinity. The results demonstrate the precursor concentration significantly influences the structural and optical properties of ZnS thin films.