Ferroelectric Properties and Polarization Fatigue of La:HfO2 Thin‐Film Capacitors. Issue 4 (27th January 2021)

• Record Type: Journal Article
• Authors: Li, Xiaofei; Li, Chen; Xu, Zhiyu; Li, Yongsheng; Yang, Yihao; Hu, Haihua; Jiang, Zhizheng; Wang, Jiayi; Ren, Jiaxin; Zheng, Chunyan; Lu, Chaojing; Wen, Zheng
• Is Part Of: Physica status solidi. Volume 15:Issue 4(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-01-27
• Subjects: domain wall pinning -- ferroelectricity -- HfO2 -- polarization fatigue -- polarization switching dynamics; Solid state physics -- Periodicals; 530.4105
• DOI: 10.1002/pssr.202000481
• Languages: English
• ISSNs: 1862-6254

Abstract

Abstract : Recently, doped HfO2 thin films have attracted considerable attention because of promising applications in complementary metal–oxide–semiconductor (CMOS)‐compatible ferroelectric memories. Herein, the ferroelectric properties and polarization fatigue of La:HfO2 thin‐film capacitors are reported. By varying the substrate lattice constant and film thickness, a robust remanent polarization of ≈16 μC cm −2 is achieved in a 12 nm‐thick Pt/La:HfO2 /La0.67 Sr0.33 MnO3 capacitor. Fatigue measurements are conducted using designed pulse sequences, in which the voltage, pulse width, and interval time are changed to observe the evolution of switchable polarization with increasing cycles. Severe fatigue is observed when the La:HfO2 capacitors are partially switched and the interval between the bipolar switching is elongated. These behaviors may be ascribed to the domain wall pinning scenario, in which domain switching is blocked by the migration and aggregation of charges on non‐electroneutral walls. Further analysis of the fatigue behaviors with a nucleation‐limited‐switching model shows that the mean time and activation field for polarization switching are increased in fatigued La:HfO2 capacitors because electrical stimuli are required to disperse the aggregated charges before the domains are set free. These results facilitate the design and fabrication of HfO2 ‐based ferroelectric memories with improved device reliability. Abstract : Recently, ferroelectric HfO2 thin films have triggered great interest. However, HfO2 ‐based memories suffer from fatigue problems, while the mechanism is under debate. In this work, it is found that severe fatigue occurs when there are more domain walls and long intervals for charge migration. These results support the domain wall pinning scenario.