Defect Engineering of HfO ₂ -Based Thin Films for Simultaneously Achieving High Polarization and Excellent Fatigue Resistance: Mediating Double-Edged Role of Oxygen Vacancies

HfO₂-based ferroelectric thin films can be used in advanced memory applications. The oxygen vacancies (VO) present in HfO₂ are essential for stabilizing the ferroelectric phase; however, they are detrimental to fatigue resistance because of domain pinning and leakage path formation induced by VO aggregation. A defect engineering strategy was developed to reconcile the contradictory role of VO in HfO₂-based ferroelectric thin films. At a 2-V operating voltage, the 8 mol % Ti-doped Hf0.5Zr0.5O₂ (HZO) ferroelectric thin film exhibited excellent ferroelectric properties and tolerated 1 × 10¹⁰ endurance cycles. First-principles calculations and X-ray photoelectron spectroscopy characterization revealed that the Ti dopants did not affect the VO concentration in HZO, but they served as a fastener for binding VO, thus impeding the aggregation and diffusion of VO under cyclic electric fields. This study provides a viable pathway to resolve the double-edged role of VO and thus enhance fatigue resistance while maintaining high polarization.