Synthesis of nanocrystalline zinc sulphide and preparation of its self-assembled thin films

We have synthesized ZnS nano-crystalline (n-ZnS) powder using zinc acetate and thiourea from chemical route at different pH. The average crystal size is determined as 3-5 nm with the help of X-ray diffraction. The formation of ZnS has been confirmed with the help of infrared (IR) spectroscopy by observing bands corresponding to the multi phonon absorption. IR spectrum also confirms presence of the capping agent on ZnS. Thin films of ZnS have also been deposited on glass and quartz substrates from the solution using self-aggregation approach. Refractive index (n) of the films is also determined. The optical band gap is calculated from the Tauc's extrapolation and is found to be dependent on pH of the bath solution. Electrical conductivity measurements have been done on these thin films and the activation energy has been calculated.