Direct Imaging of Nanoscale Ferroelectric Domains and Polarization Reversal in Ferroelectric Capacitors

TL;DR

Researchers used a new imaging technique to study tiny electric domains in ferroelectric capacitors, revealing how their structure and behavior affect device performance.

Contribution

The study introduces nano-XRD as a noninvasive method to image buried ferroelectric domains and their polarization reversal in capacitors.

Findings

Nano-XRD reveals local disorder and polarization reorientation in BiFeO3 capacitors due to boundary conditions and stress.

Electrical poling induces lattice tilt at electrode edges, potentially impacting downscaled device performance.

The method enables operando characterization of ferroelectric domain dynamics in nanoscale devices.

Abstract

Ferroelectric thin films present a powerful platform
for next-generation
computing and memory applications. However, domain morphology and
dynamics in buried ferroelectric stacks have remained underexplored,
despite their importance for real device performance. Here, nanoprobe
X-ray diffraction (nano-XRD) is used to image ferroelectric domains
inside BiFeO3-based capacitors, revealing local disorder
in domain architecture and partial polarization reorientation caused
by the capacitor electrostatic boundary conditions and internal stress.
We demonstrate sensitivity to ferroelectric reversal in poled capacitors,
highlighting expansive/compressive (001) strain for up-/down-polarization
using nano-XRD. We observe significant quantitative and qualitative
differences between poling by piezoresponse force microscopy and
in devices. Further, electrical poling induces lattice tilt at electrode
edges, which may modify performance in downscaled devices. Our results
establish nano-XRD as a noninvasive probe of buried ferroelectric
domain morphologies and dynamics, opening avenues for operando characterization
of energy-efficient nanoscale devices.

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