Structural and magnetic properties of cobalt doped ZnO thin films deposited by cost effective nebulizer spray pyrolysis technique

In this work, we report the structural, optical and magnetic properties of Co doped ZnO thin films fabricated by nebulizer spray pyrolysis technique. Five different thin films were fabricated with various doping concentration of cobalt. These thin films posses hexagonal wurtzite structure with polycrystalline nature and strongly oriented along with (002) and (101) direction. From x-ray diffraction pattern, average crystallite sizes were calculated and are found to be decreases with Co doping concentration. The dislocation density and microstrain values of the coated films increased gradually with doping concentration. The SEM/AFM studies reveal the change from spherical shape to petal shaped grains and it is also found that the size of grains and roughness decreases with Co increasing doping concentration. The lowering of the optical band gap energy from similar to 3.24 eV to 3.05 eV shows doping by Co in ZnO gives rise to band gap bowing in ZnO:Co thin films. The M-H curve confirms the god ferromagnetism in Co doped ZnO thin films.