Preparation and Characterizations of NiS/ZnS Bilayer Thinfilm by Chemical Bath Deposition Method

Abstract

NiS/ZnS thin films were grown by Chemical Bath Deposition (CBD) technique using eqimolar aqueous solutions of zinc chloride, nickel chloride and thiourea as precursor. Silicon glass substrates were placed in glass bottles with polypropylene autoclave screw caps containing the precursors described above, and the bath temperature is maintained at 95°C. X-ray diffraction 28/8 scans showed that the only crystallographic phase present was the hexagonal wurtzite structure. Scanning electron microscopy showed the formation of nanostructures, consisting of hexagonal structures of a few hundred nanometers. The photoluminescence spectra of NiS/ZnS bilayer were recorded at 18-295 K using a cw He-Cd laser (325 nm) and pulsed laser (266 nm). The NiS/ZnS nanostructure exhibit an ultraviolet emission band centered at ;:::; 3.87eV in the vicinity of the band edge, which is attributed to the well-known excitonic transition in ZnS. The optical properties such as refractive index, electrical and optical conductivities were determined by using UV- VIS absorption spectrometry. The band gap energy was determined as 1.45 eV.