Electrical, optical, structural and morphological properties of NiS films

The electrical, optical, structural and morphological properties of NiS films are less studied than other materials such as CdS, CdTe, ZnS, ZnO, CdO etc. Our aim in this work is to deposit NiS films, examine some of their physical properties and investigate their suitability for photovoltaic devices. NiS films were deposited onto glass substrates at a substrate temperature of 300 ± 5 "C using the ultrasonic spray pyrolysis (USP) technique. The variations of temperature-dependent conductivity under the conditions of light and dark were investigated and it was seen that illumination reduces conductivity. The activation energy for the doped region and the energy-gap for the intrinsic region were found as 6.79 meV and 0.90 eV. respectively. The resistivity was measured via two-probe method as 6.89 x $10^6$ ohm.cm in the voltage range 1 ? 10 V. The crystal structures were investigated by x-ray diffraction (XRD) and it was determined that the crystalline nature was not well-developed and was close to amorphous structure. The surface morphology was examined by scanning electron microscopy (SEM), with the observations that the film surfaces were not completely homogeneous. The elemental analyses were also studied by energy dispersive x-ray spectroscopy (EDS).