Abstract
Increased data storage densities are required for the next generation of nonvolatile random access memories and data storage devices based on ferroelectric materials. Yet, with intensified miniaturization, these devices face a loss of their ferroelectric properties. Therefore, a full microscopic understanding of the impact of the nanoscale defects on the ferroelectric switching dynamics is crucial. However, collecting real-time data at the atomic and nanoscale remains very challenging. In this work, we explore the ferroelectric response of a Pb(Zr0.2Ti0.8)O3 thin film ferroelectric capacitor to electrical biasing in situ in the transmission electron microscope. Using a combination of high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and differential phase contrast (DPC)-STEM imaging we unveil the structural and polarization state of the ferroelectric thin film, integrated into a capacitor architecture, before and during biasing. Thus, we can correlate real-time changes in the DPC signal with the presence of misfit dislocations and ferroelastic domains. A reduction in the domain wall velocity of 24% is measured in defective regions of the film when compared to predominantly defect-free regions.
Highlights
Ferroelectrics have found a large number of applications in modern life since their discovery a century ago [1]
We have developed a workflow to prepare ferroelectric thin film specimens on commercially available microelectromechanical systems (MEMS) half-chips using a focused ion beam (FIB) allowing more accessible in situ electrical biasing experiments
The response of a Pb(Zrx Ti1−x )O3 (PZT) thin film ferroelectric capacitor to electrical biasing has been investigated in situ by scanning TEM (STEM) imaging
Summary
Ferroelectrics have found a large number of applications in modern life since their discovery a century ago [1]. Further miniaturization of ferroelectric-based memories is hindered by major reliability issues [2,3] such as retention loss [4], imprint [5] and fatigue [6]. These are typically related to the presence of structural and charged defects, which affect the domain wall motion and domain nucleation [7,8,9]. At present, our understanding of the switching processes involved in ferroelectric systems is largely impeded by insufficient dynamical data on the atomic and nano-scale
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