Nannan Liu, Chunlai Luo, Hongdi Wu, Yecheng Ding, Xubing Lu, Zhibo Yan(颜志波), Jun-Ming Liu(刘俊明), and Guoliang Yuan(袁国亮)

Precise control of fatigue, wake-up, charge injection, and break-down in Hf0.5Zr0.5O2-based ferroelectric memories

Applied Physical Letters 124, 192905(2024)

Hf0.5Zr0.5O2 (HZO) thin films are promising for applications in ferroelectric memories. However, these materials often face challenges, such as polarization fluctuations (e.g., fatigue and wake-up) and electric break-down incidents during the “1/0” write/read cycles, hindering their industrial application. Herein, fatigue, wake-up, and electric break-down seriously depend on both the electric field for polarization switching (Es) and the charge accumulation in the HZO film. More and more charges pin ferroelectric domains, and the sub-switching polarization introduces serious ferroelectric fatigue during the 1010 write/read cycles at Es  1.2Ec, where Ec is a ferroelectric coercive field. On the contrary, new charges increase rather slowly, and complete polarization switching is realized during the 1010 cycles at Es  1.5Ec, so the HZO film presents excellent polarization stability. A high Es  2Ec introduces the strong wake-up effect first; however, the serious charge accumulation largely increases leakage current and quickly introduces an electric break-down of the HZO film. Furthermore, it was found that the leakage current and dielectric permittivity can effectively monitor the charge accumulation and provide an early warning for fatigue and electric break-down.