Research Of (Fe, Cu) And (Fe, Sn) Codoped In₂O₃ Diluted Magnetic Semiconductors

(Fe,Cu) and (Fe,Sn) codoped In2O3 powders and films were prepared by solid state reaction method, a vacuum annealing process and pulsed laser deposition in this paper. The crystalline structures and magnetic properties of these samples were studied systematically and the conclusions can be summarized as follows:(1) (In0.92Fe0.05Cu0.03)2O3 powders were prepared by a solid state reaction method and a vacuum annealing process. The X-ray diffraction results confirmed that there were not any Fe or Fe oxide secondary phases in (In0.92Fe0.05Cu0.03)2O3 samples. The magnetization of the samples depended strongly on the sinter temperature, and the saturation magnetic moment of the samples first increased and then decreased with increasing sinter temperature. Annealing in vacuum can enhance the magnetic moment of the samples effectively, and the magnetic moment of the samples increased with the annealing temperature. The oxygen vacancies played an important role in enhancing ferromagnetism of the (In0.92Fe0.05Cu0.03)2O3 powders.(2) (In0.92Fe0.05Cu0.03)2O3 thin films were deposited by pulsed laser deposition at different substrate temperatures (450℃～700℃) and oxygen partial pressures (5×10-3-100mTorr). The dependence of substrate temperatures and oxygen partial pressures on the properties of films was investigated. Structural analysis clearly indicated homogeneous films of bixbyite structure of In2O3 and there were not any Fe or Fe oxide secondary phases in (In0.92Fe0.05Cu0.03)2O3 films. Magnetic measurements indicated that the saturation magnetic moment of the films gradually increased and then decreased with the substrates temperature. While the films showed room temperature ferromagnetism when the oxygen partial pressure was low.(3) (In0.92Fe0.05Sn0.03)2O3 powders were prepared by a conventional solid state reaction method and a vacuum annealing process. There were no detectable traces of any Fe or Fe oxides secondary phases in (In0.92Fe0.05Sn0.03)2O3 samples. The result showed that Sn has no effect on magnetism of samples while annealing in vacuum can enhance the magnetic moment of the samples effectively.In conclusion, we have successfully fabricated In2O3-based DMSs by several different methods and studied the various properties of the samples. The results suggest that the oxygen vacancy plays an important role in the origin of ferromagnetism and the magnetic mechanism of In2O3-based DMSs follows the Bound Magnetic Polaron theory.