Nonlinear domain wall velocity in ferroelectric Si-doped HfO$_{2}$ thin film capacitors

TL;DR

This study examines the nonlinear behavior of domain wall velocity in ferroelectric Si-doped HfO₂ thin films, revealing thermally activated regimes and the influence of random-field defects through combined PFM and switching current analyses.

Contribution

It provides new insights into the nonlinear domain wall dynamics and defect effects in ferroelectric thin films using combined experimental techniques.

Findings

Domain wall velocity exhibits nonlinear dependence on external electric field.

Thermally activated creep and flow regimes are identified.

Random-field defects influence the switching dynamics, consistent with Lorentzian distribution.

Abstract

We investigate the nonlinear response of the domain wall velocity ($v$) to an external electric field ($E_{ext}$) in ferroelectric Si-doped HfO$_{2}$ thin film capacitors using piezoresponse force microscopy (PFM) and switching current measurements. We verified the reliability of the PFM images of ferroelectric domain switching by comparing the switched volume fraction in the PFM images with the time-dependent normalized switched polarization from the switching current data. Using consecutive time-dependent PFM images, we measured the velocity of the pure lateral domain wall motion at various $E_{ext}$. The $E_{ext}$-dependent $v$ values closely follow the nonlinear dynamic response of elastic objects in a disordered medium. The thermally activated creep and flow regimes were observed based on the magnitude of $E_{ext}$. With a dynamic exponent of ${\mu}$ = 1, our thin film was found to have random-field defects, which is consistent with the Lorentzian distribution of characteristic switching time that was indicated in the switching current data.