Ellipsometric Spectra and Optical Properties of Anisotropic SrBi₂Ta₂O₉ Films

Ellipsometric spectra of the SrBi₂Ta₂O₉ (SBT) films of (200) and (0010) predominant orientation are measured and analysed in the range of photon energy from 2 to 5 eV. The results show that the oriented SBT films appear to be strongly anisotropic. The ellipsometric spectra of the (200)-predominant SBT films are different from those of the (0010)-predominant films. We suggest an analysis model for these oriented films and perform the fitting of the anisotropic ellipsometric spectra. The refractive index and the extinction coefficient of the ordinary ray and the extraordinary ray for these oriented SBT films are obtained. The ordinary refractive index is larger than the extraordinary one.