Switching properties of epitaxial La0.5Sr0.5CoO3/Na0.5Bi0.5TiO3/La0.5Sr0.5CoO3 ferroelectric capacitor

Abstract

La_0.5Sr_0.5CoO₃/Na_0.5Bi_0.5TiO₃/La_0.5Sr_0.5CoO₃ (LSCO/NBT/LSCO) ferroelectric capacitors have been successfully fabricated on (001) SrTiO₃ substrate, in which the LSCO film is prepared by magnetron sputtering and the NBT film by pulsed laser deposition. Both X-ray diffraction and transmission electron microscopy techniques confirm that the (001) oriented LSCO/NBT/LSCO heterostructure is epitaxially grown on SrTiO₃ substrate. The remnant polarization, coercive field and relative dielectric constant of the LSCO/NBT/LSCO capacitor, measured at 250 kV cm⁻¹, are 15.6 μC cm⁻², 47 kV cm⁻¹ and 559, respectively. Moreover, the capacitor possesses very good fatigue-resistance, and less pulse width dependence as well as piezoelectric properties (d₃₃ = 145 pm V⁻¹). It is found that the leakage current density of the LSCO/NBT/LSCO capacitor meets well with ohmic conduction behavior at applied fields lower than 55 kV cm⁻¹ and bulk-limited space charge-limited conduction at the fields higher than 55 kV cm⁻¹.