Excellent Ferroelectricity and Thermal Stability in Ce-Doped HfO₂ Thin Films via Oxygen Vacancy Modulation

This study introduces cerium (Ce) doping as a controllable strategy to regulate oxygen vacancy (V_O) concentration and stabilize the metastable orthorhombic phase in HfO₂ thin films. Ce dopants, with low defect formation energy and high solubility, promote V_O formation and reduce the free energy of the orthorhombic phase, enhancing its stability. Guided by first-principles calculations, chemical solution deposition was used to prepare Ce-doped HfO₂ thin films, enabling precise control over V_O concentration and addressing the limitations of traditional post-treatment methods that struggle to control V_O. The optimized Ce_0.2Hf_0.8O₂ film exhibits a high remanent polarization (2P_r ≈ 45 μC/cm²), a low coercive field (E_c ≈ 1.08 MV/cm), an endurance lifetime surpassing 10¹⁰ cycles, excellent retention (94.8%), and stable ferroelectricity up to 200 °C. These findings highlight the potential of Ce-doped HfO₂ for high-temperature nonvolatile memory (NVM) applications and provide a pathway for designing other high-performance HfO₂-based systems.