Microstructure and crystallographic orientation dependence of electrical properties in lead zirconate thin films prepared by sol-gel process

Lead zirconate (PbZrO3) thin films are grown on Pt(111)/Ti/SiO2/Si(100) substrates by sol-gel using precursor solutions with stoichiometric and 20 mol% excess Pb. Films with no preferred orientation and [111] pseudocubic texture (denoted as [111]pc) are obtained by changing the drying temperature at the pyrolysis stage. Randomly oriented films were found to have a two-phase microstructure consisting of large rosette-type perovskite regions with a nanocrystalline phase located in between. The ratio of the rosettes increase to cover the entire surface of the films with the increase of Pb content. The films with [111]pc orientation have a uniform microstructure with micron size grains. The electrical properties of the films were influenced markedly by the microstructure and orientation of the films. The [111]pc oriented films exhibit a square-like double hysteresis loop with maximum polarization (Pmax) reaching 61x10-6 C/cm2 under 550 kV/cm, whereas stoichiometric films with no preferred orientation have a Pmax of 36x10-6 C/cm2 with slimmer hysteresis curves. (author)