Effects of acid catalyst on the nanostructure of nickel sulfide thin films prepared by spin coating method

In this work, we report for the first time the effect of acidic medium on the structural, morphological, compositional, topographical and electrical properties of nickel sulfide thin films (NiS2). NiS2 thin films were deposited on a glass substrate by the spin coating method. The synthesized samples were characterized using Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electronic microscopy (SEM), energy-dispersive X-ray (EDX) spectra, four-point probe measurement and atomic force microscopy (AFM). The presence of the relevant chemical bonds Ni–S–Ni, Ni–S and S–S were ascertained through FT-IR spectroscopy. XRD analysis revealed a nanostructured cubic phase of the grown (NiS2) nanostructure, where the crystallite size was in the range 7 − 10 nm. SEM revealed that the sample without a catalyst exhibited smaller pore sizes and a dense morphology with spherical grains. EDX analysis confirms the presence of all elements forming NiS2. The NiS2 thin film with acetic acid was found to have the smallest sheet resistance of $$1.23\times 10^2\; {\Omega}$$ . Atomic force microscopy analysis was used to confirm spherical surface morphology and current transport properties. (TUNA mode) provides information on the electrical conductivity of NiS2 thin films together with its spherical morphology in the nm range. The current-voltage (I–V) curves show ohmic behavior indicating high conductivity spread over the surface of the samples. This work, by investigating the connection between the electrical and nanostructural characteristics of NiS2 thin films, will pave the way for future device applications.