Interface-oxygen-loss-controlled voltage offsets in epitaxial Pb(Zr₀.₅₂Ti₀.₄₈)O₃ thin-film capacitors with La₀.₇Sr₀.₃MnO₃ electrodes

Abstract

Epitaxial Pb(Zr₀.₅₂Ti₀.₄₈)O₃(PZT) thin-film capacitors with La₀.₇Sr₀.₃MnO₃(LSMO) electrodes have been grown on (LaAlO₃)₀.₃(SrAl₀.₅Ta₀.₅O₃)₀.₇ (001) substrates by pulsed-laser deposition. The process-induced imprint behavior in the ferroelectric capacitors was examined by in situ and ex situ annealing at various conditions. It was found that for the capacitors in situ annealed at reduced oxygen pressures, where the LSMO electrodes are stable, voltage offsets in the polarization-electric field hysteresis loops were observed only for those treated at temperatures higher than the Curie temperature. At lower temperatures, the oxygen loss may be suppressed by stresses arising primarily from the paraelectric-to-ferroelectric transformation. However, for the capacitors ex situ annealed at the same low temperature, large voltage offsets were induced due to the oxygen instability of the LSMO electrodes. We show evidence that the imprint is caused by oxygen loss at the PZT∕LSMO interface, and closely related to the variation of the PZT structure.