Preparation of nanocrystalline Ni doped ZnS thin films by ammonia-free chemical bath deposition method and optical properties

•Nanocrystalline ZnS:Ni thin films were prepared by the chemical bath deposition method.•The size of ZnS:Ni nanocrystals was less than 10 nm showing quantum size effect.•SEM images demonstrated a dense and uniform surface that was free of pinholes.•The deposited films were highly transparent (>70%) in the visible region.•The PL spectra of ZnS:Ni thin films showed two emission peaks at 430 and 523 nm.

Nanocrystalline Ni doped ZnS thin films were deposited on quartz, silicon, and glass substrates using chemical bath deposition method in a weak acidic solution containing ethylenediamine tetra acetic acid disodium salt (Na2EDTA) as a complexing agent for zinc ions and thioacetamide (TAA) as a sulfide source at 80 °C. The films were characterized by energy-dispersive X-ray spectrometer (EDX), inductively coupled plasma atomic emission spectroscopy (ICP-AES), Fourier transform-infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible spectrophotometry, and photoluminescence (PL) spectroscopy. UV-vis transmission data showed that the films were transparent in the visible region. The X-ray diffraction analysis showed a cubic zinc blend structure. FE-SEM revealed a homogeneous morphology and dense nanostructures. The PL spectra of the ZnS:Ni films showed two characteristic bands, one broad band centered at 430 and another narrow band at 523 nm. Furthermore, concentration quenching effect on the photoluminescence intensity has been observed.