Recent progress on defect-engineering in ferroelectric HfO2: The next step forward via multiscale structural optimization

• Published in: Materials horizons 2024-02, Vol.11 (3), p.626-645
• Main Authors: Yan, Fengjun, Wu, Yao, Liu, Yilong, Pu Ai, Liu, Shi, Deng, Shiqing, Kan-Hao Xue, Fu, Qiuyun, Dong, Wen
• Format: Article
• Language: English
• Subjects: Doping; Ferroelectric materials; Ferroelectricity; Ferroelectrics; Fluorite; Hafnium oxide; Ion bombardment; Optimization; Phase transitions; Point defects; Solid solutions; State-of-the-art reviews; Thin films
• ISSN: 2051-6347; 2051-6355
• DOI: 10.1039/d3mh01273e

The discovery of unconventional scale-free ferroelectricity in HfO2-based fluorite thin films has attracted great attention in recent years for their promising applications in low-power logic and nonvolatile memories. The ferroelectricity of HfO2 is intrinsically originated from the widely accepted ferroelectric metastable orthorhombic Pca21 phase. In the last decade, defect-doping/solid solution has shown excellent prospects in enhancing and stabilizing the ferroelectricity via isovalent or aliovalent defect-engineering. Here, the recent advances in defect-engineered HfO2-based ferroelectrics are first reviewed, including progress in mono-ionic doping and mixed ion-doping. Then, the defect-lattice correlation, the point-defect promoted phase transition kinetics, and the interface-engineered dynamic behaviour of oxygen vacancy are summarized. In addition, thin film preparation and ion bombardment doping are summarized. Finally, the outlook and challenges are discussed. A multiscale structural optimization approach is suggested for further property optimization. This article not only covers an overview of the state-of-art advances of defects in fluorite ferroelectrics, but also future prospects that may inspire their further property-optimization via defect-engineering.