Enhanced Ferroelectric Functionality in Flexible Lead Zirconate Titanate Films with In-Situ Substrate-Clamping Compensation

Much attention has been given recently to flexible and wearable integrated-electronic devices, with a strong emphasis on real-time sensing, computing and communication technologies. Thin ferroelectric films exhibit switchable polarization and strong electro-mechanical coupling, and hence are in widespread use in such technologies, albeit not when flexed. Effects of extrinsic strain on thin ferroelectric films are still unclear, mainly due to the lack of suitable experimental systems that allow cross structural-functional characterization with in-situ straining. Moreover, although the effects of intrinsic strain on ferroelectric films, e.g. due to film-substrate lattice mismatch, have been investigated extensively, it is unclear how these effects are influenced by external strain. Here, we developed a method to strain thin films homogenously in-situ, allowing functional and structural characterization while retaining the sample under constant straining conditions in AFM and XRD. Using this method, we strained the seminal ferroelectric, PbZr0.2Ti0.8O3 that was grown on a flexible mica substrate, to reduce substrate clamping effects and increase the tetragonality. Consequently, we increased the domain stability, decreased the coercive field value and reduced imprint effects. This method allows also direct characterization of the relationship between the lattice parameters and nanoscale properties of other flexible materials.