The Interplay Between Ferroelectricity and Electrochemical Reactivity on the Surface of Binary Ferroelectric AlxB1‐xN

• Published in: Advanced electronic materials Vol. 10; no. 2
• Main Authors: Liu, Yongtao, Ievlev, Anton, Casamento, Joseph, Hayden, John, Trolier‐McKinstry, Susan, Maria, Jon‐Paul, Kalinin, Sergei V., Kelley, Kyle P.
• Format: Journal Article
• Language: English
• Published: Wiley-VCH 01-02-2024
• Subjects: aluminum boron nitride; electrochemical; ferroelectrics; piezoresponse force microscopy
• ISSN: 2199-160X; 2199-160X
• DOI: 10.1002/aelm.202300489

Polarization dynamics and domain structure evolution in ferroelectric Al0.93B0.07N 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 Al0.93B0.07N surface and a 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 an 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.
In ambient piezoresponse force microscopy experiments, it is discovered that applying bias to aluminum boron nitride thin films causes surface expansion and reduced electromechanical response due to tip‐induced electrochemical reactions in the presence of water. The surface expansion is suppressed when the same experiments are carried out in a controlled environment with low humidity.