A Time-Domain Perspective on the Structural and Electronic Response in Epitaxial Ferroelectric Thin Films on Silicon.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39042437.
- Also identified by DOI 10.1021/acs.nanolett.4c00712 and PMC identifier 11311524.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
This operando study of epitaxial ferroelectric Pb(Zr<sub>0.48</sub>Ti<sub>0.52</sub>)O<sub>3</sub> capacitors on silicon substrates studies their structural response via synchrotron-based time-resolved X-ray diffraction during hysteresis-loop measurements in the 2-200 kHz range. At high frequencies, the polarization hysteresis loop is rounded and the classical butterfly-like strain hysteresis acquires a flat dumbbell shape. We explain these observations from a time-domain perspective: The polarization and structural motion within the unit cell are coupled to the strain by the piezoelectric effect and limited by domain wall velocity. The solution of this coupled oscillator system is derived experimentally from the simultaneously measured electronic and structural data. The driving stress σ<sub>FE</sub>(<i>t</i>) is calculated as the product of the measured voltage <i>U</i>(<i>t</i>) and polarization <i>P</i>(<i>t</i>). Unlike the electrical variables, σ<sub>FE</sub>(<i>t</i>) and η(<i>t</i>) of the ferroelectric oscillate at twice the frequency of the applied electrical field. We model the measured frequency-dependent phase shift between η(<i>t</i>) and σ<sub>FE</sub>(<i>t</i>).