Ferroelectric La-Sr-Co-O/Pb-Zr-Ti-O/La-Sr-Co-O heterostructures on silicon via template growth

Abstract

Ferroelectric Pb0.9La0.1Zr0.2Ti 0.8O3 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.