Endurable Ferroelectricity in Ho-Doped HfO₂ Epitaxial Thin Films

HfO₂-based thin films possess the merits of robust ferroelectricity at the nanoscale and compatibility with modern Si technology, show great potential in nanoelectronics. However, the high coercive field (E_c) of such fluorite-structure oxide ferroelectrics usually leads to undesired endurance performance and dielectric breakdown, which impedes their practical applications. Herein, the Ho-doped HfO₂ (HHO) film with high polarization and superior ferroelectric endurance is reported, enabled by local structural engineering through holmium doping and thickness modulation. The predominantly (111)-oriented films display enhanced remanent polarization (35 µC cm^-2) and excellent endurance without failure even after 10¹¹ electric field cycles. The evolved rhombohedral distortion and stronger chemical bonding, regulated by local structure engineering, can avoid defect aggregation to overcome the undesirable fatigue drawback in the ferroelectric phase (Pca2₁). These results are significant in stabilizing ferroelectric hafnia-based films and make them more suitable for long-lasting device applications.