Effects of thermal treatment on structural, optical and electrical properties of NiO thin films

The spin-coating technique was utilized to produce thin films of nickel oxide on glass substrates. Three drying temperatures, 160 degrees C, and 200 degrees C, and 250 degrees C were used. Annealing temperatures ranged from 300 degrees C to 60 degrees C. The effects of drying and annealing temperatures on the films were examined with X-ray diffraction, scanning electron microscopy, Raman spectroscopy, UV-vis spectrophotometry and linear four-point probe measurements. The crystallinity of the films was found to improve as the annealing temperature increased. The average crystallite size varied from 14 nm to 28 nm for films that were dried at 200 degrees C and 14 nm-32 nm for films that were dried at 250 degrees C as the annealing temperature was increased. Optical transmittance of the films from 800 nm to 350 nm, varied from 64% to 96%. Two peaks at 558 cm(-1) and 1100 cm(-1) in the Raman spectra of the films confirmed the presence of NiO on the films.