Far-infrared properties of sol-gel derived PbZr0.52Ti0.48O3 thin films on Pt-coated substrates

摘要

Polycrystalline tetragonal PbZr0.52Ti0.48O3 (PZT) thin films have been deposited on the nickel and (111) platinum coated (110) sapphire substrates by the sol-gel method. Optical properties of the PZT thin films were studied using far-infrared reflectivity spectroscopy in the 200-10 000 cm(-1) frequency range at 300 K. The frequency dependence of the optical characteristics (sigma, epsilon, - Im epsilon(-1)) of the films were calculated by the Kramers-Kronig transformation of the reflectivity spectra and analysed by the Drude-Lorentz model. The frequency dependence of the optical conductivity, sigma(omega), of the PZT films deposited on platinum coated sapphire is well described by the free-carrier term and an overdamped mid-infrared component. Sapphire/Pt/PZT structures reveal semiconductor properties (effective carrier concentration N/m* is up to 10(20) cm(-3), plasma minimum is located near 3000 cm(-1)). This effect can be related to the favourable influence of the platinum electrode on the charge carrier density at Pt/PZT contact and formation of the interfacial conductive layer. [References: 22]