Direct Observation of Asymmetric Domain Wall Motion in a Ferroelectric Capacitor

Journal
Acta Materialia
Date
2013.10.15
Abstract
Reversible switching of ferroelectric polarization has been extensively explored for a wide range of applications including transistor and memory devices. Here we report in-situ observations of the polarization switching process of a planar PbZr0.2Ti0.8O3 (PZT) capacitor using transmission electron microscopy. We observed the preferential, but asymmetric, nucleation and forward growth of switched domains at the PZT/electrode interfaces arising from the built-in electric field beneath each interface. The subsequent sideways growth was inhibited by the depolarization field due to the imperfect charge compensation at the counter electrode and preexisting 90° domain walls, leading to asymmetric switching. It was found that preexisting 90° domains split into 180°/90° stripe domains during switching, indicating that these domains also actively participate in out-of-plane polarization switching. Our real-time observations uncovered the origin of switching asymmetry and shed new light on understanding the importance of charged domain walls and interfaces on the switching processes.
Reference
Acta Materialia 61 (2013) 6765?6777
DOI
http://dx.doi.org/10.1016/j.actamat.2013.07.051