Optical constants and band gap determination of Pb0.95La0.05Zr0.54Ti0.46O3 thin films using spectroscopic ellipsometry and UV-visible spectroscopy

We report the structural evolution and optical properties of lanthanum doped lead zirconate titanate (PLZT) thin films prepared on Pt/TiO2/SiO2/Si substrates by chemical solution deposition. X-ray diffraction demonstrates the post-deposition annealing induced crystallization for PLZT films annealed in a temperature (T-alpha) range of 550-750 degrees C. PLZT films annealed at higher temperature exhibit polycrystalline structure along with larger grain size. Optical band gap (E-g) values determined from UV-visible spectroscopy and spectroscopic ellipsometry (SE) for PLZT films were found to be in the range of 3.5-3.8 eV. E-g decreases with increasing T-alpha. The optical constants and their dispersion profiles for PLZT films were also determined from SE analyses. PLZT films show an index of refraction in the range of 2.46-2.50 (lambda = 632.8 nm) with increase in T-alpha. The increase in refractive index at higher T-alpha is attributed to the improved packing density and crystallinity with the temperature. (C) 2015 Published by Elsevier B.V.