Effects of Deposition Time of ZnS Thin Film on Optical and Morphological Properties of ZnS Deposited by Chemical Bath Deposition Method for Photovoltaic Application

Abstract

The effect of deposition time was investigated on optical and morphological properties of synthesized ZnS thin film. ZnS thin films were prepared at different temperatures and different deposition period of 1 hour, 2 hours and 3 hours onto the glass substrates by chemical bath deposition technique at a deposition temperature of 50 °C. The precursor was prepared using a mixed aqueous solution of zinc sulphate as a source of zinc and thiourea as a source of sulphur while ammonia serves as complexing agent. After the deposition, the thickness of the samples was determined using the double weighing method, the morphological and optical properties of the films were determined using Scanning Electron Microscope (PHENON WORD), UV-visible double beam spectrophotometer (ATICO) respectively. The result shows that transmittance spectral increases in the visible region of wavelength 400nm to 800nm and decreases in the infrared region at above 800nm wavelength. The transmittance spectra of the film deposited for 2 hours shows the highest value of 70% while the films deposited for 1 hour and 3 hours have the transmittance of 55% and 37% respectively. The extrapolated optical band gap energy for the film deposited is between 3.6-3.8 eV. The microstructural images of all the samples were rough and the grains were dense. The samples deposited for 3 hours and 2 hours are more clustered and smoother compared to the sample deposited for 1 hour.