Optical functions of Ca-modified PbTiO3 thin films determined by spectroscopic ellipsometry

Calcium-modified lead titanate thin films deposited on Si(100) substrate have been prepared by sol–gel processing. The structural properties of the thin films have been studied by X-ray diffraction. The ellipsometric spectra of the Pb1−xCaxTiO3 (x=0.0–0.4) films have been obtained in the spectral range of 2.2–5.0 eV, and their optical constants (the refractive index n and the extinction coefficient k) determined. The results show that after doping Ca, the refractive indexes of the Pb1−xCaxTiO3 films increase, the maximum value of refractive indexes and the absorption edges shift to lower energy.