Abstract

• Nickel Oxide (NiO) thin films were synthesized on glass substrates from aqueous solution of nickel chloride hexahydrate (NiCl2.6H2O), potassium persulfate (K2S2O8), ammonia in which ammonia was employed as complexing agents in the presence of hydroxyl solution. NiO thin films were prepared by Chemical Bath Deposition (CBD) method at different deposition time (60, 75 and 90) min. The structural, surface morphological and optical properties of 450 ºC- annealed NiO thin films were investigated. The XRD studies revealed that NiO thin films were polycrystalline nature with cubic structure. Surface morphology, average grain size and thickness of NiO thin films were estimated from different SEM micrographs. The optical absorbance and transmittance spectra of NiO thin films were recorded in the wavelength range 200 nm - 1100 nm. The sharp absorption peaks of all NiO films were observed at below 400 nm. It was found that NiO thin films with high transmittance in visible region. The refractive index, extinction coefficient and optical conductivity were calculated from the optical measurements. The direct optical energy band gap of 450ºC –annealed NiO films was found to be in the range 3.43 eV3.76eV.