Mn doped Zinc oxide thin films were prepared by metal organic chemical vapor deposition technique. Structural characterizations by X-ray diffraction technique and photoluminescence indicate the crystal quality of ZnO films. Photoluminescence and Raman showed a large fraction of oxygen vacancies (VO2+) were generated by vacuum annealed the film. The enhancement of ferromagnetism in post-annealed (Mn, In) co-doped ZnO could result from VO2+ incorporation. The effect of VO2+ on the magnetic properties of (Mn, In) co-doped ZnO was studied by first-principles calculations. It was found that only In donor could not induce ferromagnetism in Mn-doped ZnO. Besides, the presence of VO2+ made the Mn empty 3d-t2g minority state broadened, and a t2g-VO2+ hybrid level at the conduction band minimum forms. The presence of VO2+ could lead to strong ferromagnetic coupling with the nearest neighboring Mn cation by BMP model based on defects revealed that the ferromagnetic exchange was mediated by the donor impurity state, which mainly consists of Mn 3d electrons trapped in oxygen vacancies.

Ferromagnetism Induced by Oxygen-Vacancy Complex in (Mn,In) Codoped ZnO. Wu, K., Gu, S., Tang, K., Zhu, S., Zhou, M., Huang, Y., Xu, M., Zhang, R., Zheng, Y.: Physica B, 2012, 407[13], 2429–33