Optical properties of Pb(Zr 0.53Ti 0.47)O 3 thin films on Pt-coated Si substrates measured by spectroscopic ellipsometry in the UV–vis–NIR region

Abstract

Pb(Zr 0.53Ti 0.47)O 3 (PZT) thin films grown on Pt-coated Si substrates were prepared by a sol–gel process. Crystalline structure characterisation and optical constants (refractive index n, extinction coefficient k) and bandgaps E g of PZT thin films annealed at 550, 600 and 650 °C were obtained by X-ray diffraction (XRD) and spectroscopic ellipsometry (SE) in the UV–vis and near-infrared range of 235–1700 nm. A four-phase fitting model was employed to describe the optical properties of the PZT thin films; the spectra of their optical constants and the bandgap energy E g were determined by means of optimisation. The refractive index n, absorption coefficient α and bandgaps E g of crystalline PZT thin films on Pt-coated Si substrates annealed at 550–650 °C are lager than that of pure PbZrO 3 and PbTiO 3 thin films. In addition, the refractive index dispersion data related to the structure of the films agreed well with Cauchy dispersion relationship. The dependencies of the refractive index, the extinction coefficient and the optical bandgap energy on annealing temperature were analysed.