In this work the effect of annealing temperature on optical properties of zinc sulfide (ZnS) thin films grown on glass substrates by sol-gel spin-coating method is investigated. Different annealing temperature (300, 400 and 500º?) were used for investigation. Zinc acetate (Zn (CH3COO) 2.2H2O) and thiourea (CH4N2S) were used as precursors. 2-methoxyethanol and monoethanolamin were used as solvent and stabilizer respectively. Spectroscopic ellipsometry method was used to calculate the optical properties of ZnS thin films such as refractive index, extinction coefficient, dielectric function and optical band gap energy. An optical model consisting of a glass substrate / ZnS thin film / surface roughness layer / air structure was used to calculate the optical parameters. The measured spectroscopic ellipsometry parameters Ψexp and Δexp are fitted against the designed model by minimizing the mean square error (MSE). Considering the data obtained, it can be deduced that the optical properties of ZnS films is highly influenced by annealing temperature. The refractive index of the films were increased with increasing annealing temperature of the films. From these the optical band gap of the ZnS films were measured between 3.00 eV and 3.33 eV.
Spectroscopic Ellipsometry; Annealing Temperature; Thin Film; Zinc Sulfide; Optical Properties.