Optical Properties of Copper-Zinc Sulphide Network from Mixed Single Solid Source Precursors of Copper and Zinc Dithiocarbamates

Thin films of copper-zinc sulphide (CxZn1-xS) have been deposited by metal-organic chemical vapour deposition (MOCVD) technique at 400 °C on soda-lime substrates. The films contained copper dithiocarbamate and zinc dithiocarbamate of various concentrations. The effect of the precursor’s concentration was investigated using Fourier transforms infrared (FTIR) spectroscopy and UV-Vis Spectrophotometer. The precursors’ FTIR spectrums have the characteristics of copper sulphide and zinc sulphide absorption bands below 800 cm-1. The optical properties for all the samples were studied by reading the absorbance and transmittance spectra in the range of 300 - 900 nm. The results indicate direct bandgap energy that ranged between 2.20 to 3.42 eV. The films were found to have a very high transmittance in the visible and near-infrared regions and an average reflectance of about 0.14 in the same regions. Optical constants like refractive index, extinction coefficient, and optical conductivity were estimated as a function of photon energy. The various properties exhibited by the films indicate that the films can find application in various optoelectronic devices.