Optical and electrical properties of polycrystalline and amorphous PZT thin films prepared by the sol-gel technique

Abstract

Lead zirconate titanate thin films on silicon wafers and titanium foils were fabricated by the sol-gel technique. Polycrystalline and amorphous PZT thin films were obtained at the heat- treatment temperature of 650 degree(s)C and 400 degree(s)C, respectively. The microstructures of these films ere determined by x-ray and electron diffraction and HRTEM techniques. the optical refractive index of both polycrystalline and amorphous PZT films were measured by ellipsometer. The optical refractive index of polycrystalline films increases with increasing film thickness; however, the optical refractive index of amorphous films is independent of the film's thickness. the electrical properties of the PZT thin films were measured. for both polycrystalline and amorphous PZT thin films a ferroelectric hysteresis loop and pyroelectric current were observed. The dielectric permittivity of amorphous PZT is much lower than that of polycrystalline PZT. For the optical applications, the advantages of ferroelectriclike amorphous PZT materials are low processing temperature, ease of deposition on a variety of substrates (including glass and plastic), and transparency without grain boundaries. In this paper, the preparation, optical, and electrical characterizations, as well a microstructures of these thin films, are reported.