Characteristics of constrained ferroelectricity in PbZrO 3/BaZrO 3 superlattice films

Abstract

An Artificially layered perovskite composed of antiferroelectric PbZrO 3 and paraelectric BaZrO 3 (BZO) was fabricated on LaNiO 3/Pt/Ti/SiO 2/Si substrates at 475 °C by radio-frequency magnetron sputtering. It had an (001)-oriented superlattice structure with an average composition of (Pb 0.75Ba 0.25)ZrO 3 (PBZ). X-ray diffraction, cross-sectional transmission electron microscopy, and a depth profile of a secondary-ion mass spectrometer confirmed the formation of superlattice structure with designed composition modulation. Ferroelectricity was induced in the superlattice films, and the ferroelectric as well as the dielectric properties were enhanced with reducing the stacking periodicity. The remanent polarization P r and coercive field E c were found linearly dependent on the applied voltage but independent of the measurement temperature up to 100 °C. The retention loss of superlattice films was small and significantly less than that of (Pb 1-xBa x)ZrO 3 (PBZ) solid-solution films either at room temperature or 100 °C. The dielectric constant of the superlattice films was also found insensitive to temperature up to 175 °C, but not for the PBZ solid-solution film, which exhibited a clear dielectric maximum at the Curie temperature of 125 °C. Moreover, a significant suppression of leakage current down to 10 -8-10 -9 A/cm 2 was obtained in the superlattice films constructed with the wide-bandgap sublayer of BZO. © 2005 American Institute of Physics.