Effect of Deposition Time on the Properties of NiS Films Prepared by Chemical Bath Deposition

Abstract

Objectives: To study the influence of deposition time on the physical behavior of NiS films formed by chemical bath deposition (CBD). Methods: Polycrystalline NiS thin films were deposited by using CBD method on glass substrates by varying the deposition time in the range of 60–150 min with the other growth conditions kept constant. The physical properties were measured using an X-ray diffractometer, Scanning Electron Microscopy with Energy Dispersive X-ray analyzer, and Fourier transform infrared spectra. Finally, the optical and electrical properties of the films were analyzed by using UV-Vis spectrophotometer and linear four-probe point method respectively. Findings: The X-ray Diffraction (XRD) studies showed polycrystalline nature of the films with hexagonal structure, confirmed by the Rietveld refinement analysis. The calculated crystallite size varied from 6 nm to 19 nm with the increase in deposition time. The EDS analysis revealed the stoichiometry of Ni and S in the samples. The optical bandgap decreases from 2.06 eV to 1.93 eV with the increase in deposition time. The films synthesized using a deposition time of 120 min at 80 ◦C showed a high electrical conductivity of 48.3 S/cm at room temperature with activation energy of 0.16 eV. Novelty: NiS thin films were deposited by the CBD method using different deposition times varying from 60 min. to 150 min., keeping the bath temperature constant at 80 ◦C for the first time. The Rietveld refinement analysis was the first of its kind, reported on the structural evaluation of NiS layers. These films were formed using eco-friendly materials adding value to the solar cell application. Keywords: Thin films; Absorber layer; CBD method; XRD; FTIR