Hydrothermally deposited PbTiO₃ epitaxial thin film

A hydrothermal method is a unique method to deposit ferroelectric thin films by utilizing chemical reaction in solutions. In addition to the low reaction temperature below 200°C, its simple process procedure, automatically aligned polarization and three-dimensional deposition are advantages. In this study, a lead titanate epitaxial thin film was obtained on a strontium ruthenate bottom electrode sputterd on strontium titanate (100). High-resolution X-ray diffraction mapping showed that the film was perfectly c-axis-oriented. Transmission electron microscope observation revealed that the film had no lattice dislocation at the interface between lead titanate and strontium ruthenate. A remanent polarization of 96.5 μC/cm² was measured with a single-crystal-like DE hysteresis curve. Observation by scanning nonlinear dielectric microscopy indicated that this film did not contain any defect such as an a-domain or a grain boundary, even on the nano scale. With various pulse parameters, nano-domain dots were patterned and the minimum dot radius of an inverted domain was 12 nm, corresponding to a data storage density of 1 Tbit/inch².