Controllable Preparation of Millimeter-Scale In-Plane Charged Domain Wall in a Lead-Free Ferroelectric Film

Ferroelectric domain walls are emerging as active components in nanoelectronics, offering a transformative paradigm for non-volatile memory and logic technologies. In particular, in-plane charged domain walls stand out for their potential to support unique functionalities, such as quantum confinement and tunneling effects, unlocking new possibilities for advanced device applications. Here, a facile approach is developed for fabricating large-scale continuous in-plane charged domain walls in Na_0.5Bi_0.5TiO₃ ferroelectric films through thermally optimized growth control. Using Differential Phase Contrast Scanning Transmission Electron Microscopy, an electric field fluctuation is identified across the charged domain wall. This fluctuation is accompanied by oxygen octahedron distortions, which allow the lattice to redistribute charges, as confirmed by integrated Differential Phase Contrast analyses. Additionally, Electron Energy Loss Spectroscopy reveals variations in titanium oxidation states across the domain wall, which compensates for the charge accumulation and enhances the stability of the charged domain wall. This work presents a wafer-scale fabrication strategy for in-plane charged domain walls and provides atomic-scale insights into their stabilization mechanisms, offering a foundation for their integration into domain-wall-based nanodevices and on-chip applications.