Effects of Charge Imbalance on Field‐Induced Instability of HfO₂‐Based Ferroelectric Tunnel Junctions

Abstract

Ferroelectricity in hafnium‐based materials has attracted significant research attention and is used in various applications owing to their complementary metal‐oxide‐semiconductor compatibility, scalability, and low‐power operation. However, their widespread integration into various technologies is hindered by reliability and stability problems, particularly field‐induced instability, which causes fluctuations in polarization characteristics during operation. Herein, on the underlying mechanism of field‐induced instability is reported in pure hafnium oxide films within metal‐ferroelectric‐insulator‐semiconductor (MFIS) ferroelectric tunnel junctions (FTJs). The comprehensive material analysis combined with low‐frequency noise (LFN) measurements reveals that the presence of oxygen vacancies and interface traps within the ferroelectric and dielectric layers induces a charge imbalance in the FTJ, leading to distortion in its polarization characteristics and the onset of cyclic evolution in field‐induced instability. Furthermore, high‐pressure annealing effectively mitigates field‐induced instability by reducing the defects within the film, thereby alleviating the associated charge imbalance. These findings contribute to a deeper understanding of the internal dynamics of FTJs and provide an efficient approach to enhancing their stability.