Hill Megan O, Kim Ji Soo, Müller Moritz L, Phuyal Dibya, Taper Sunil, Bansal Manisha, Becker Maximilian T, Bakhit Babak, Maity Tuhin, Monserrat Bartomeu, Martino Giuliana Di, Strkalj Nives, MacManus-Driscoll Judith L
Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, CB3 0FS, UK.
MAX IV Laboratory, Lund University, Lund, 221 00, Sweden.
Adv Mater. 2024 Nov;36(45):e2408572. doi: 10.1002/adma.202408572. Epub 2024 Sep 12.
The discovery of ferroelectricity in nanoscale hafnia-based oxide films has spurred interest in understanding their emergent properties. Investigation focuses on the size-dependent polarization behavior, which is sensitive to content and movement of oxygen vacancies. Though polarization switching and electrochemical reactions is shown to co-occur, their relationship remains unclear. This study employs X-ray photoelectron spectroscopy with depth sensitivity to examine changes in electrochemical states occurring during polarization switching. Contrasting HfZrO (HZO) with HfLaTaO (HLTO), a composition with an equivalent structure and comparable average ionic radius, electrochemical states are directly observed for specific polarization directions. Lower-polarization films exhibit more significant electrochemical changes upon switching, suggesting an indirect relationship between polarization and electrochemical state. This research illuminates the complex interplay between polarization and electrochemical dynamics, providing evidence for intrinsic polar states in HfO-based ferroelectrics.
纳米级氧化铪基薄膜中铁电性的发现激发了人们对理解其新兴特性的兴趣。研究重点在于尺寸依赖的极化行为，这种行为对氧空位的含量和移动很敏感。尽管已表明极化切换和电化学反应会同时发生，但其关系仍不明确。本研究采用具有深度敏感性的X射线光电子能谱来检查极化切换过程中发生的电化学状态变化。将具有等效结构和可比平均离子半径的HfZrO（HZO）与HfLaTaO（HLTO）进行对比，针对特定极化方向直接观察到了电化学状态。低极化薄膜在切换时表现出更显著的电化学变化，这表明极化与电化学状态之间存在间接关系。这项研究阐明了极化与电化学动力学之间的复杂相互作用，为基于HfO的铁电体中的固有极化状态提供了证据。
