Ce:YIG薄膜中氧空位对光吸收性能的影响

Effect of the oxygen vacancy of Ce:YIG films on optical absorption properties

讨论了Ce替代石榴石薄膜制备条件对其光吸收性能的影响。通过引入氧空位概念,提出了溅射气氛中的氧含量对薄膜中Ce元素价态影响的理论模型。基于该模型,讨论了Ce:YIG晶体中氧空位的产生机理。研究表明,当晶格中存在过量氧空位时,会导致部分Fe3+被还原成Fe2+,使得薄膜的光吸收显著增大。实验结果证实,在Ce:YIG薄膜的晶化过程中,采用富氧气氛可以使得薄膜中Ce元素的价态以Ce3+离子为主而Ce4+离子含量较少,从而有效降低薄膜的光吸收。溅射气氛中的氧含量及后续热处理过程中氧含量的大小均会直接影响Ce:YIG薄膜的光吸收特性。

In this paper,the effect of the preparation condition of cerium substituted yttrium iron garnet （Ce：YIG） film on its magnetooptical properties and optical absorption was discussed. The oxygen vacancies concept was introduced into Ce：YIG energy band theory model, to explain the compositions of the sputtering gas was key factor to influence the properties of the films, Based on this theory model, the mechanism of origin of oxygen vacancies and how does it to affect the optical absorption of Ce：YIG thin film were discussed. The research shows that excess oxygen vacancies result in much high optical absorption due to the reduction of Fe^3＋ to Fe^2＋. Experiment results confirm that proper content of oxygen can be used to control the level of oxygen vacancies in the crystal, in order to obtain the films with Ce^3＋ ions dominant compared with Ce^4＋, and the optical absorption decreased considerably then, So the oxygen content in both sputtering gas during films growth process and in subsequent annealing process influence the optical absorption properties directly.