The film thickness effect on the physical properties of NiO thin films elaborated by Sol-gel method

Abstract

In this work, nickel oxide (NiO) was elaborated on glass substrate at by sol-gel technique. The NiO thin films were prepared with 0.8 M Ni(NO3)2 6H2O annealed at 600 °C for 2 h. The coating process was repeated for 13, 14, 15, 16 and 17 times to obtain a thin film, which corresponded to 124, 137, 143, 147 and 166 nm of film thickness. NiO thin films were observed as nanocrystalline with cubic structure at 166 nm with (111) and (200) peaks were observed. All NiO thin films have an average transmittance of about 80 % in the visible region. The NiO thin films have a variety in the band gap energy from 3.87 to 3.94 eV. Because of the effect of deposition times, the minimum value was found at 166 nm where this condition has the highest Urbach energy. The NiO thin films have an electrical conductivity which was increased from 7.94 x10-3 to 84x10-3 (Ω.cm)-1 when film thickness increases from 124 to 137 nm. In the end, the electrical measurements were investigated by the four-point method, with the results show good electrical conductivity at 166 nm.