Morphological, Structural and Optical Properties of Ba-Doped NiO Nanostructure Thin Films

Abstract

This paper reports the effect of barium doping on NiO thin films. Undoped and doped films thin films were deposited on a glass substrate at 450 °C using pneumatic spray pyrolysis technique (PSPT) with different concentrations of barium (0 -8 at. %). X-ray diffraction patterns show the polycrystalline nature of the films with the preferred orientation (111). No other barium metal cluster and impurity phases have been observed with Ba doping. The crystal size of the deposited thin films was calculated using the Debye-Scherrer formula for the two orientations ( 111) and ( 200), and from the SEM photographs, we found values ranging from 11.95 to 39.06 nm in both cases. In the visible region, the optical transmission of Ba-doped NiO thin films dropped by up to 46 % when compared to undoped NiO thin films (79 %). The band gap was found to be decreasing in the range of 3.742 -3.503 eV with Ba doping. The Urbach disorder energy clearly increases from 262.98 to 356.64 meV when passing from the undoped thin layer to the thin layer doped at 2 at. %, then decreases to the minimum 303.14 meV for a barium doping of 8 at. %, allowing the atoms to find a good site, i.e. thin films become homogeneous and highly crystallized. The roughness was calculated using SEM image analysis. Its values were ranged between 23.26 -39.06 nm.