In this study,Cobalt (Co)-doped to Zinc Oxide (ZnO)samples prepared as thin films were obtained using spray pyrolysis. The prepared thin films have different concentrations of Cobalt. Scanning electron microscope, X-ray diffraction, and optical spectroscopy have been used to investigate the effect of Co concentration on the physical properties of deposited thin films. The grain size has been obtained using Scherrer's equation.From the obtained results, the grain size behaviouris non-linearly with Co-concentration level. The fabricated thin films studied using electron spin resonance (ESR) to observe the resonance absorption of microwave radiation by the spins of an electron of a molecule or an atom in a magnetic field.The study was performed before and after irradiation doses of 1 KGy and 3 KGy.The ESR signal show ferromagnetic response at room temperature which is imporoved after irradiation with gamma ray.
The optical band gap of pure ZnO film was found to be 3.25 eV and the minimum bandgap is 3.11 for 1wt%. The existence of Co in the obtained film was confirmed by Energy Dispersive X-Ray (EDX)data. The percentage of Co was found to increase from 1.9% to 5.4% as the wt% increases. Films are irradiated with gamma ray with 1KGy and 3 KGy. The effect of this irradiation on the magnetic and structural properties was investigated. Magnetic measurements for all prepared samples show a Room Temperature Ferromagnetic (RTFM) behaviour. The ESR signal is dependent on the increase of both Co concentration and gamma-ray irradiation dose.