Ultralow fatigue in hafnia-based ferroelectric capacitors achieved by suppressing cycling-induced phase transitions through unconventional oxygen-vacancy redistribution

Abstract

Hafnia (HfO2)-based ferroelectric devices face reliability challenges stemming from the fact that the polar phase is metastable. The highest reported ferroelectric fatigue-endurance value stands at 1012 cycles, quite good but insufficient for high-ranking applications. Especially, the remnant polarization upon the fatigue testing degrades drastically at elevated temperatures. This study proposes an innovative strategy to achieve excellent fatigue-resistant performance by designing the (Hf0.5Zr0.5O2/ZrO2)n superlattices, characterized by the measured fatigue-endurance value of 1012 cycles at an elevated temperature of 400 K (2.0 MV/cm). Notably, the extrapolated fatigue-endurance number at room temperature reaches an impressive high value of 5.26 × 1017 cycles. This superior fatigue endurance can be attributed to the effective suppression of the orthorhombic (O) to monoclinic (M) in the Hf0.5Zr0.5O2 layer and orthorhombic to tetragonal (T) phase transitions in the ZrO2 layer due to the redistribution of oxygen vacancies during electric field cycling. This work establishes a promising pathway for fabricating long-lifetime and temperature-tolerant robust hafnia-based ferroelectric devices for advanced applications.