Undoped nickel oxide (NiO) thin films were deposited on 500 ∘ C heated glass substrates using spray pyrolysis method at (0.015-0.1 M) range of precursor. The latter was obtained by decomposition of nickel nitrate hexahydrate in double distilled water. Effect of precursor concentration on structural, optical, and electrical properties of NiO thin films was investigated. X-ray diffraction (XRD) shows the formation of NiO under cubic structure with single diffraction peak along (111) plane at 2 = 37.24 ∘ . When precursor concentration reaches 0.1 M, an increment in NiO crystallite size over 37.04 nm was obtained indicating the product nano structure. SEM images reveal that beyond 0.04 M as precursor concentration the substrate becomes completely covered with NiO and thin films exhibit formation of nano agglomerations at the top of the sample surface. Ni-O bonds vibrations modes in the product of films were confirmed by FT-IR analysis. Transparency of the films ranged from 57 to 88% and band gap energy of the films decreases from 3.68 to 3.60 eV with increasing precursor concentration. Electrical properties of the elaborated NiO thin films were correlated to the precursor concentration.

Undoped Nickel oxide (NiO) thin films were deposited on 500 ˚C heated glass using spray pyrolysis technique. Effect of volume sprayed solution on structural and optical properties of NiO thin films was studied. Volume amount was ranged in 5 -30 ml and stepped by 5ml. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and UV-visible spectrophotometer were used to investigate elaborated thin films. XRD results show that the deposited films with volume lower than 10 ml is amorphous and with increasing volume up to 10 ml NiO thin films structure become polycrystalline with cubic structure and (111) as preferential orientation. An increase in diffraction intensity of preferred peak and narrowing in full width at half maximum were observed with sprayed volume increasing, which leads to better crystallinity of NiO thin films. Also it was observed that the grain size increased with increasing volume solution and were averaged in 10 -28 nm. FT-IR analysis of product confirms the NiO bond formation and the results were compared with previous studies. All films exhibit an average optical transparency between 50 % and 80 % in the visible range and their band gap values are ranged in 3.38 -3.62 eV.