Interface‐Modulated Antiferroelectric‐to‐Ferroelectric‐Like Transition in Ultrathin Hf_0.5Zr_0.5O₂ Films

Abstract The development of ultrathin (≤5 nm) hafnia‐based ferroelectric (FE) films is essential for achieving low operating voltages, facilitating their integration into advanced process nodes for low‐power and non‐volatile memory applications. However, challenges in ultrathin FE films arise from the depolarization field and interface‐related issues, leading to an antiferroelectric‐like (AFE‐like) polarization switching behavior and more significant wake‐up effects, causing operational inconvenience and reliability concerns. Here, interface‐modulated ferroelectricity is reported in 4 nm Hf 0.5 Zr 0.5 O 2 (HZO) thin films, demonstrating excellent properties with low operating voltage, enhanced switching speed, and high reliability. Electrical and structural characterizations reveal that adjusting interface asymmetry may introduce a substantial built‐in field ( E bi ) and an AFE‐like switching behavior can exhibit a robust FE‐like characteristic. This AFE‐to‐FE‐like transition is driven by switching kinetics rather than commonly proposed phase transitions. Furthermore, a comprehensive model is developed to elucidate the intricate physics of the modulation mechanism by asymmetric interfaces, emphasizing the critical roles of depolarizing effects and E bi on ferroelectricity. This work underscores the importance of interfaces in engineering ferroelectricity for advanced electronic applications.