Fatigue Behaviour of Pb(Zr,Ti)O3/PbZrO3 Multilayer Ferroelectric Thin Films

Abstract

Fatigue behaviour of Pb(Zr0.45Ti0.55)O3 (PZT) thin films on Pt(111)/Ti/SiO2/Si(100) substrates with PbZrO3 (PZ) buffer layers were investigated. Two different buffer layer configurations were studied: bottom- and top-only buffer layers. The PZ buffer layers were obtained by RF magnetron sputtering of a loose powder target containing a mixture of PbZrO3 and ZrO2 powders. The PZT thin films were prepared by sol–gel spin coating method. All of the films had well-crystallized, uniform and dense microstructure with full (111) orientation. The bottom buffer layers influenced the nucleation and grain growth of the upper PZT layers creating a bimodal grain size distribution. Secondary ion mass spectrometry (SIMS) elemental depth profiles indicated that a PZ buffer layer led to well-defined and sharp composition profiles. The P–E hysteresis measurements indicated comparable remnant polarization values (2Pr=40–50 µC/cm2) and coercive field levels (2Ec=150–180 kV/cm) with un-buffered film. The fatigue endurance of PZT thin films with PZ buffer layers was superior than the un-buffered counterpart. A fatigue-free behaviour was observed up to 109 switching cycles.