ZnS was chemically deposited as a buffer layer alternative to CdS, for use as a Cd-free buffer layer in Cu(In_1-xGa_x)Se₂ (CIGS) solar cells. The deposition of a thin film of ZnS was carried out by chemical bath deposition, following which the structural and optical properties of the ZnS layer were studied. For the experiments, zinc sulfate hepta-hydrate (ZnSO₄·7H₂O), thiourea (SC(NH₂)₂), and ammonia (NH₄OH) were used as the reacting agents. The mole concentrations of ZnSO₄ and SC(NH₂)₂ were fixed at 0.03 M and 0.8 M, respectively, while that of ammonia, which acts as a complexing agent, was varied from 0.3 M to 3.5 M. By varying the mole concentration of ammonia, optimal values for parameters like optical transmission, deposition rate, and surface morphology were determined. For the fixed mole concentrations of 0.03 M ZnSO₄·7H₂O and 0.8 M SC(NH₂)₂, it was established that 3.0 M of ammonia could provide optimal values of the deposition rate (5.5 nm/min), average optical transmittance (81%), and energy band gap (3.81 eV), rendering the chemically deposited ZnS suitable for use as a Cd-free buffer layer in CIGS solar cells.

In this study, chemical bath deposition method was used to grow Zinc sulfide(ZnS) thin filmsfrom NH3/SC(NH2)2/ZnSO4 solutions at 90℃. ZnS thin films have been prepared onto ITO glass. Theconcentrations of ZnSO4 and NH were varied while the concentration of Thiourea was fixed in 0.52 M. Structural, optical, electrical characteristic of ZnS thin films were measured. The physical and opticalproperties of different ZnS thin films were influenced severely by the concentration of the two reactingchemicals. The optimal concentration of ZnSO4 and NH3 was 0.085 M and 1.6 M, respectively.

Znic sulfide (ZnS) thin films were deposited on glass substrates by radio frequency magnetron sputtering. The substrate temperature varied from room temperature (RT) to 500℃. The structural and optical properties of ZnS films were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive analysis of X-ray (EDAX) and UV-visible transmission spectra. The XRD analyses reveal that ZnS films have cubic structures with (111) preferential orientation, whereas the diffraction patterns sharpen with the increase in substrate temperatures. The FESEM images indicate that ZnS films deposited at 400℃ have nano-sized grains with a grain size of∼ 67 nm. The films exhibit relatively high transmittance of 80% in the visible region, with an energy band gap of 3.71 eV. One obvious result is that the energy band gap of the film increases with increasing the substrate temperatures.