Reversible fatigue-rejuvenation procedure and its mechanism in Hf_0.5Zr_0.5O₂ epitaxial films

Abstract HfO2-based ferroelectrics, such as Hf0.5Zr0.5O2, 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 Hf0.5Zr0.5O2 epitaxial films and investigate the fatigue mechanism. The experimental data show that the remanent ferroelectric polarization value decreased by 50% after 108 cycles. It is worth noting that the fatigued Hf0.5Zr0.5O2 epitaxial films can be recovered through applying electric stimulus. Combined with the temperature-dependent endurance analysis, we propose that fatigue of our Hf0.5Zr0.5O2 films comes from both phase transition between ferroelectric Pca21 and 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.