Influence of Annealing Temperature on Mn-doped ZnO Diluted Magnetic Semiconductor Thin Films

In this paper, we report the effects of Mn2+ and the defect on ferromagnetism in Mn-doped ZnO thin films prepared by radio frequency magnetron sputtering at different annealing temperature below 600 degrees C. The result of superconducting quantum interference device reveals that the sample which annealed at 500 degrees C realized ferromagnetism till room temperature. The X-ray diffraction results shows that the samples are wurtzite structure and the sample annealed at optimum temperature gets relatively better crystallinity. X-ray photoelectron spectroscopy results show clear evidence of oxygen vacancy increment for the samples which annealed at 500 degrees C. Our results indicate that Mn2+ ions replace the Zn sites and no evidence for either metallic Mn or Mn-related oxide in the samples. It was concluded that the existence of ferromagnetism was closely related to the concentration of Mn2+ and the defect of the ZnO matrix.