Reversible fatigue-rejuvenation procedure and its mechanism in Hf_0.5Zr_0.5O₂epitaxial films

HfO₂-based ferroelectrics, such as Hf_0.5Zr_0.5O₂, arouse great attention in recent years because of their CMOS compatibility and robust nano-scale ferroelectricity. However, fatigue is one of the toughest problems for ferroelectric applications. The fatigue mechanism of HfO₂-based ferroelectrics is different from conventional ferroelectric materials, and research on the fatigue mechanism in HfO₂-based epitaxial films have been rarely reported. In this work, we fabricate 10 nm Hf_0.5Zr_0.5O₂epitaxial films and investigate the fatigue mechanism. The experimental data show that the remanent ferroelectric polarization value decreased by 50% after 10⁸cycles. It is worth noting that the fatigued Hf_0.5Zr_0.5O₂epitaxial films can be recovered through applying electric stimulus. Combined with the temperature-dependent endurance analysis, we propose that fatigue of our Hf_0.5Zr_0.5O₂films comes from both phase transition between ferroelectric Pca2₁and antiferroelectric Pbca as well as defects generation and dipole pinned. This result offers a fundamental understanding of HfO₂-based film system, and could provide an important guideline for subsequent studies and future applications.