Influence of Na and F doping on microstructures, optical and magnetic properties of ZnO films synthesized by sol-gel method

Undoped, Na-doped, and Na-F codoped ZnO films were synthesized using sol-gel method. Na+ and F+ ions were used as two different dopants that yielded a synergistic doping effect. This effect was measurable using XRD, accompanied by a redshift in the optical bandgap from 3.284 to 3.261 eV in ZnO, ZnO-F, and ZnO-Na-F thin films, respectively. We then studied the resulting photoluminescent changes, which were attributed to O-related defects. Ferromagnetism measurements revealed that magnetic orderings decreased significantly with F doping. However, increased Na doping enhanced the oxygen-vacancy mediated ferromagnetic state.