Electrical and magnetic properties of (Al, Co) co-doped ZnO films deposited by RF magnetron sputtering

In this work, (Al, Co)-ZnO films were co-sputtered on glass substrate through radio frequency sputtering at 100 degrees C. The film's structure, electrical and magnetic properties as a function of Al doping content is investigated. The results indicate that (Al, Co)-ZnO films crystallinity can be suppressed by Co doping or (Co, Al) co-doping. With the substitution of Zn2+ by Al3+, the film's conductivity improves. All the films present ferromagnetic behavior at room temperature. Upon increasing the Al doping amount, the film's saturation magnetization expresses a carrier-concentration dependent behavior. Three different regions can be defined, where BMP model and carrier-mediated exchange mechanisms play a role in the various regions.