The effect of various complexing agents on the morphology and optoelectronic properties of chemically deposited ZnS thin films: A comparative study

Thin films of ZnS were synthesized on glass substrates by chemical bath deposition technique. The effect of three different complexing agents, viz. hydrazine hydrate (HH), triethanolamine (TEA) and trisodiumcitrate (TSC) on the growth and physical properties of ZnS films has been investigated. The experimental results indicated that the complexing agents affect the structure, lattice strain, surface morphology and optoelectronic properties of ZnS films significantly. X-ray diffraction studies disclosed that all the ZnS layers crystallized in hexagonal form and the predominant orientations of the crystallites differed with complexing agents. Thickness of the films profoundly varied with the complexing agents though the deposition parameters like time, temperature and pH of reaction baths were kept constant. Atomic Force Microscopy revealed the variation in surface topography and roughness of the films. The film with HH as complexing agent exhibited maximum transmittance (87%) in the visible region of electromagnetic spectrum whereas those synthesized using TEA and TSC had a lower transmittance of approximately 60% and 50% respectively. The corresponding values of optical band gap were found to be 3.73, 3.64 and 3.57 eV respectively. The room temperature photoluminescence emission spectra consisted of bright blue emission peaks for all the samples. The intensity of emission peak was found to be maximum for TSC film and minimum for HH film.