Microstructure and ferroelectric properties of epitaxial cation ordered PbSc_0.5Ta_0.5O₃ thin films grown on electroded and buffered Si(100)

Epitaxial PbSc_0.5Ta_0.5O₃ (001) films with an epitaxial LaNiO₃ bottom electrode were deposited on CeO ₂/yttria-stabilized zirconia-buffered Si (100) substrates. Crystal orientation, in-plane and out-of-plane lattice parameters, surface morphology, and microstructure were analyzed by X-ray diffraction, X-ray reciprocal lattice mapping measurements, atomic force microscopy, and transmission electron microscopy, respectively. XRD superstructure reflections indicate that the films are cation ordered. Polarization-field and switching current-voltage hysteresis curves were measured at room temperature. The measured spontaneous polarization P_s, remnant polarization P_r, and coercive voltage V _c were found to be 14 μC/cm², 4 μC/cm², and 1.1 V, respectively, at room temperature. Furthermore, field as well as frequency dependence of the dielectric constant were measured at room temperature. Piezoelectric measurements performed on these PST films showed a sharp non-linearity, which is attributed to the possibility of field induced phase transition and/or percolation of polar nano regions.