氧分压对BiFeO_3薄膜能带结构和折射率的影响及其光学表征

The influence of oxygen partial pressure on the energy band and refractive index of BiFeO_3 thin films grown by RF-magnetron sputtering and its optical characterization

采用射频磁控溅射在玻璃衬底上制备了BiFeO3薄膜,通过透射光谱和椭圆光谱研究了氧分压对BiFeO3薄膜能带结构及光学性能的影响。结果表明,BiFeO3薄膜在近红外区具有良好的透射性,透射率均在80%以上,其禁带宽度Eg=(2.79±0.03)eV。随着氧分压的增大,BiFeO3薄膜中氧缺陷及氧缺陷能级减少,导致透射率和禁带宽度均增大。同时发现,OJL色散模型与Cauchy色散模型的叠合能够对BiFeO3薄膜的椭圆光谱进行很好的描述。

Multiferroic BiFeO3 thin films were prepared on glass substrates by radio frequency magnetron sputtering.The effect of O2 partial pressure on the energy band and the optical properties of BiFeO3 thin films have been studied by transmission spectra and ellipsometric spectra.The results reveal that the transmittance of BiFeO3 thin films is more than 80%,and the band gap of BiFeO3 thin films is Eg=（2.79±0.03）eV.The oxygen defects and defect levels of BiFeO3 thin films decrease with increment of O2 partial pressure,which results in the increasing of the transmittance and energy gap Eg.It is also found that the cauchy-OJL dispersion model can explain spectroscopic ellipsometric data in our films.