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.