Ferroelectric Pb0.9La0.1Zr0.2Ti0.8O3 thin film capacitors with a symmetrical La-Sr-Co-O top and bottom electrodes have been grown on [001] Si with yttria stabilized zirconia (YSZ) buffer layer. A layered perovskite ‘‘template’’ layer (200–300 Å thick), grown between the YSZ buffer layer and the bottom La-Sr-Co-O electrode, is critical for obtaining the required orientation of the subsequent layers. When compared to the capacitors grown with the Y-Ba-Cu-O top and bottom electrodes, these structures possess two advantages: (i) the growth temperatures are lower by 60–150 °C; (ii) the capacitors show a larger remnant polarization ΔP (ΔP=switched polarization–nonswitched polarization), 25–30 μC/cm2, for an applied voltage of only 2 V (applied field of 70 kV/cm). The fatigue, retention, and aging characteristics of these new structures are excellent.

Fatigue and retention characteristics of ferroelectric lead zirconate titanate thin films grown with Y-Ba-Cu-O(YBCO) thin-film top and bottom electrodes are found to be far superior to those obtained with conventional Pt top electrodes. The heterostructures reported here have been grown in situ by pulsed laser deposition on yttria-stabilized ZrO2 buffer [100] Si and on [001] LaAlO3. Both the a- and c-axis orientations of the YBCO lattice have been used as electrodes. They were prepared using suitable changes in growth conditions.

We report on the effect of cooling rate on the crystallographic orientation and ferroelectric properties of PbZr0.2Ti0.8O3 (PZT) thin films grown on a lattice matched bottom electrode such as c-axis oriented Y-Ba-Cu-O (YBCO). The cooling rate from deposition temperature influences the crystallographic orientation of the ferroelectric c axis of the PZT film as well as the electrical properties of the YBCO bottom electrode. As the volume fraction of the ferroelectric phase with the c axis in the plane of the film becomes higher, the hysteresis loops become more rounded and the polarization values become smaller. Highly c-axis oriented films, obtained by cooling from the growth temperature at 20 °C/min, show an almost square hysteresis loop with the largest polarization values.

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We have fabricated epitaxial ferroelectric PbZr0.2Ti0.8O3/YBa2Cu3O7−x heterostructures on single crystalline [001] LaAlO3. Only the (00l) peaks of the PbZr0.2Ti0.8O3 (PZT) film are observed, indicating that the epitaxial, c-axis oriented YBCO film is a good structural template for the heteroepitaxial growth of PZT films, in addition to being a metallic bottom electrode. A saturation polarization and remanence as high as 38 and 26.5 μC/cm2 (at 7.5 V, 0.5 kHz), respectively, have been achieved. The coercive field is about 100 kV/cm.