Structural Defect Impact on Changing Optical Response and Raising Unpredicted Ferromagnetic Behaviour in (111) Preferentially Oriented Nanocrystalline NiO Films

NiO thin films deposed on a glass substrate, “NiO/glass”, are successfully prepared using a spray pyrolysis technique (SPT) at 460 °C and characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray, Atomic force microscopy (AFM), spectroscopic ellipsometry (SE), Photoluminescence (PL) and diverse electric and magnetic studies. The structural investigation shows that the synthesized films crystallized in a cubic structure with (111) preferential orientation. The NiO layers exhibit a uniform grain of regular sizes with aggregates randomly distributed across their surface. The optical properties of the NiO thin films evidenced a normal optical dispersion as well as good transparency of the NiO films. An unpredicted ferromagnetic aspect was raised due to the high oxygen presence in the synthetized material. A high thermal dependency of the conductivity, as well as a semiconductor behavior of the grown NiO material, is also demonstrated.