Zhou Chao, Ma Liyang, Feng Yanpeng, Kuo Chang-Yang, Ku Yu-Chieh, Liu Cheng-En, Cheng Xianlong, Li Jingxuan, Si Yangyang, Huang Haoliang, Huang Yan, Zhao Hongjian, Chang Chun-Fu, Das Sujit, Liu Shi, Chen Zuhuang
School of Materials Science and Engineering, Harbin Institute of Technology, Shenzhen, 518055, China.
Key Laboratory for Quantum Materials of Zhejiang Province, Department of Physics, School of Science, Westlake University, Hangzhou, Zhejiang, 310024, China.
Nat Commun. 2024 Apr 3;15(1):2893. doi: 10.1038/s41467-024-47194-8.
In the realm of ferroelectric memories, HfO-based ferroelectrics stand out because of their exceptional CMOS compatibility and scalability. Nevertheless, their switchable polarization and switching speed are not on par with those of perovskite ferroelectrics. It is widely acknowledged that defects play a crucial role in stabilizing the metastable polar phase of HfO. Simultaneously, defects also pin the domain walls and impede the switching process, ultimately rendering the sluggish switching of HfO. Herein, we present an effective strategy involving acceptor-donor co-doping to effectively tackle this dilemma. Remarkably enhanced ferroelectricity and the fastest switching process ever reported among HfO polar devices are observed in La-Ta co-doped HfO ultrathin films. Moreover, robust macro-electrical characteristics of co-doped films persist even at a thickness as low as 3 nm, expanding potential applications of HfO in ultrathin devices. Our systematic investigations further demonstrate that synergistic effects of uniform microstructure and smaller switching barrier introduced by co-doping ensure the enhanced ferroelectricity and shortened switching time. The co-doping strategy offers an effective avenue to control the defect state and improve the ferroelectric properties of HfO films.
在铁电存储器领域，基于HfO的铁电体因其出色的CMOS兼容性和可扩展性而脱颖而出。然而，它们的可切换极化和开关速度与钙钛矿铁电体不相上下。人们普遍认为，缺陷在稳定HfO的亚稳极性相中起着至关重要的作用。同时，缺陷还会固定畴壁并阻碍开关过程，最终导致HfO的开关速度迟缓。在此，我们提出一种涉及受主-施主共掺杂的有效策略，以有效解决这一难题。在La-Ta共掺杂的HfO超薄膜中，观察到铁电性显著增强，且是HfO极性器件中迄今报道的最快开关过程。此外，即使在低至3nm的厚度下，共掺杂薄膜仍具有稳健的宏观电学特性，拓展了HfO在超薄器件中的潜在应用。我们的系统研究进一步表明，共掺杂引入的均匀微观结构和较小开关势垒的协同效应确保了铁电性增强和开关时间缩短。共掺杂策略为控制缺陷状态和改善HfO薄膜的铁电性能提供了一条有效途径。
