Mapping Ferroelectric Fields Reveals the Origins of the Coercivity Distribution.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39017620.
- Also identified by DOI 10.1021/acsnano.4c04526 and PMC identifier 11308779.
- 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
Better techniques for imaging ferroelectric polarization would aid the development of new ferroelectrics and the refinement of old ones. Here we show how scanning transmission electron microscope (STEM) electron beam-induced current (EBIC) imaging reveals ferroelectric polarization with obvious, simply interpretable contrast. Planar imaging of an entire ferroelectric hafnium zirconium oxide (Hf<sub>0.5</sub>Zr<sub>0.5</sub>O<sub>2</sub>, HZO) capacitor shows an EBIC response that is linearly related to the polarization determined <i>in situ</i> with the positive-up, negative-down (PUND) method. The contrast is easily calibrated in MV/cm. The underlying mechanism is magnification-independent, operating equally well on micrometer-sized devices and individual nanoscale domains. Coercive-field mapping reveals that individual domains are biased "positive" and "negative", as opposed to being "easy" and "hard" to switch. The remanent background <i>E</i>-fields generating this bias can be isolated and mapped. Coupled with STEM's native capabilities for structural identification, STEM EBIC imaging provides a revolutionary tool for characterizing ferroelectric materials and devices.