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 (P max) reaching 61×10-6 C/cm2 under 550 kV/cm, whereas stoichiometric films with no preferred orientation have a P max of 36×10-6 C/cm2 with slimmer hysteresis curves.