Microstructure and room temperature ferromagnetism of Cu-doped ZnO films

Cu-doped ZnO films were deposited on (0 0 0 1) sapphire substrates by radio frequency (RF) magnetron sputtering. PIXE and SR-XRD analyses excluded the ferromagnetic contamination and the existence of the clusters or second phases formed by magnetic atoms or Cu atoms. Cu atoms were incorporate into ZnO crystal lattice by occupying the sites of zinc atoms as shown by EXAFS analyses. Room temperature ferromagnetism has a strong correlation not only with Cu atoms but also with oxygen vacancy (Vo).