Alternating atomic-dipole layers and switching dynamics in Al <sub>1-x</sub> Sc <sub>x</sub> N ferroelectrics
Abstract
Wurtzite Al 1-x Sc x N ferroelectrics exhibit exceptional polarization and thermal stability, making them highly promising for a wide range of electronic applications. However, a more profound understanding is required regarding the atomic-scale mechanism through which cation substitution lowers the switching energy barrier and thus reduces the coercive field. We used spherical aberration–corrected transmission electron microscopy to reveal a periodic modulation of cation-anion spacing along the polarization direction, forming alternating atomic dipole layers. This modulation arises from energetically favorable chemical ordering of aluminum and scandium atoms between adjacent layers, with layer-resolved asymmetry in atomic arrangement. In situ imaging directly captures atomic-scale, noncollective, stepwise polarization switching, revealing intermediate states and local spacing fluctuations. Compositional inhomogeneity in these dipole layers creates multiple transient states that reduce the switching energy barrier. Our findings connect atomic-scale dipole structures to polarization switching kinetics, enabling the rational design of wurtzite ferroelectrics.
Article Details
Journal Info
Science
American Association for the Advancement of Science
Authors (13)
Yonghui Zheng
Key Laboratory of Polar Materials and Devices (MOE), School of Information and Electronic Engineering (School of Integrated Circuits Science and Engineering), East China Normal University, Shanghai, China.
Ruirong Bai
Key Laboratory of Polar Materials and Devices (MOE), School of Information and Electronic Engineering (School of Integrated Circuits Science and Engineering), East China Normal University, Shanghai, China.
Tianjiao Xin
Key Laboratory of Polar Materials and Devices (MOE), School of Information and Electronic Engineering (School of Integrated Circuits Science and Engineering), East China Normal University, Shanghai, China.
Xuanyu Zhao
State Key Laboratory of Integrated Chips and Systems, Frontier Institute of Chip and System, College of Integrated Circuits and Micro-Nano Electronics, Fudan University, Shanghai, China.
Yan Cheng
Key Laboratory of Polar Materials and Devices (MOE), School of Information and Electronic Engineering (School of Integrated Circuits Science and Engineering), East China Normal University, Shanghai, China.
Yu-Ning Wu
Key Laboratory of Polar Materials and Devices (MOE), School of Information and Electronic Engineering (School of Integrated Circuits Science and Engineering), East China Normal University, Shanghai, China.
Yingfen Wei
State Key Laboratory of Integrated Chips and Systems, Frontier Institute of Chip and System, College of Integrated Circuits and Micro-Nano Electronics, Fudan University, Shanghai, China.
Binghui Ge
State Key Laboratory of Opto-Electronic Information Acquisition and Protection Technology, Anhui University, Hefei, China.
He Tian
Center of Electron Microscopy, School of Materials Science and Engineering, Zhejiang University, Hangzhou, China.
Shiyou Chen
Key Laboratory of Computational Physical Sciences (MOE), College of Integrated Circuits and Micro-Nano Electronics, Fudan University, Shanghai, China.
Qi Liu
Chungang Duan
Key Laboratory of Polar Materials and Devices (MOE), School of Information and Electronic Engineering (School of Integrated Circuits Science and Engineering), East China Normal University, Shanghai, China.
Ming Liu