Nanostructure and enhancement of the optical properties of Tb-doped NiO for photodiode applications

In the present work, pure and 1, 2.5, 5 and 10% Tb-doped NiO nanostructures were fabricated in the form of thin-films by the sol-gel spin coating process. The prepared structures were identified by an X-ray diffraction pattern and atomic force microscopy. The results of the X-ray diffraction indicate that the prepared films are polycrystalline with a cubic lattice face-centered for wholly Tb-doped concentration films. The surface topography of the films was studied by atomic force microscopy, and surface mapping was introduced to check the quality of the surface for optical investigations. The measured optical transmission indicated a high transmission that exceeds 80% through the visible region depending on the Tb-doping concentrations. It is affirmed that the measured optical bandgap and the index of refraction are strongly influenced by the Tb-doping concentrations. The parameters of nonlinearity were also critically affected by the Tb-doping concentrations. This innovative result can hopefully be applied in an industrialized approach for the field of photodiode devices.