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 (V_O) 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 V_O aggregation. A defect engineering strategy was developed to reconcile the contradictory role of V_O in HfO₂-based ferroelectric thin films. At a 2-V operating voltage, the 8 mol % Ti-doped Hf_0.5Zr_0.5O₂ (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 V_O concentration in HZO, but they served as a fastener for binding V_O, thus impeding the aggregation and diffusion of V_O under cyclic electric fields. This study provides a viable pathway to resolve the double-edged role of V_O and thus enhance fatigue resistance while maintaining high polarization.