Heat Post-Treatment Effect on Optical and Electrical Properties of ZnS Thin Films

Heat post-treatment involves subjecting the ZnS thin film to a high-temperature annealing process after deposition on a substrate. The primary goal of heat post-treatment is to improve the crystalline structure of the ZnS film, which can significantly impact its electrical and optical properties. Zinc sulfide (ZnS) films are broadly utilized in photovoltaic instruments because of their versatile properties. In this study, we deposited ZnS films on glass substrates using spin coating at a temperature of 500°C and investigated the impact of film thickness on their optical and electrical characteristics. We employed various characterization techniques such as UV-visible (UV-V) spectroscopy, X-ray diffraction (XRD), and two-point techniques to analyze the electrical and optical properties of ZnS thin films. During the heat treatment, the ZnS film is annealed, which promotes the formation of well-defined crystalline grains and reduces the number of defects in the film. A thin Zinc Sulfide film shows the film's thickness from 445 nm to 1778 nm. The electrical resistivity of the films was also measured and found to be in the range of 8.34 × 105 to 56.71 × 105 Ohm-m. Our results demonstrate the significant impact of film thickness on the electrical and optical properties of ZnS films, which can be useful in developing photovoltaic devices.