Spectroellipsometric characterization of multilayer sol-gel Fe2O3 films

Multilayer Fe2O3 films were deposited by the sol-gel method on glass substrates using three successive deposition procedures. The films were thermally treated for 1 h at 300 C. The optical and microstructural properties of these films were investigated by spectroscopic ellipsometry (SE) in the 500-1000 nm range. The optical gap was found by fitting the dispersion of the film refractive index (n) with the Wemple-DiDomenico (WDD) formula. The ellipsometric measurements showed also that the Fe2O3 films are anisotropic. The birefringence values (Deltan) of the sol-gel films (0.05-0.08) are smaller than the large values of the Fe2O3 (which are around 0.28) but increase with the crystalization of the films. AFM measurements showed that the films treated at 300degreesC start to crystallize.