The interplay between ferroelectricity and electrochemical reactivity on the surface of binary ferroelectric Al$_x$B$_{1-x}$N

TL;DR

This study investigates how ferroelectric polarization and surface electrochemical reactions in Al$_{0.93}$B$_{0.07}$N influence surface morphology and stability, highlighting environmental effects on material functionality.

Contribution

It reveals the impact of electrochemical reactivity on surface morphology and polarization stability in ferroelectric Al$_x$B$_{1-x}$N under different atmospheric conditions.

Findings

Negative biases cause surface protrusions and reduce electromechanical response.

Surface morphology remains stable in controlled atmospheres with minimal changes.

Ambient environment induces surface topographical changes at electrode edges during cycling.

Abstract

Polarization dynamics and domain structure evolution in ferroelectric Al$_{0.93}$B$_{0.07}$N are studied using piezoresponse force microscopy and spectroscopies in ambient and controlled atmosphere environments. The application of negative unipolar, and bipolar first-order reverse curve (FORC) waveforms leads to a protrusion-like feature on the Al$_{0.93}$B$_{0.07}$N surface and reduction of electromechanical response due to electrochemical reactivity. A surface change is also observed on the application of fast alternating current bias. At the same time, the application of positive biases does not lead to surface changes. Comparatively in a controlled glove box atmosphere, stable polarization patterns can be observed, with minuscule changes in surface morphology. This surface morphology change is not isolated to applying biases to free surface, a similar topographical change is also observed at the electrode edges when cycling a capacitor in ambient environment. The study suggests that surface electrochemical reactivity may have a significant impact on the functionality of this material in the ambient environment. However, even in the controlled atmosphere, the participation of the surface ions in polarization switching phenomena and ionic compensation is possible.