Reducing Coercive Field and Improving Endurance in Ferroelectric Epitaxial Hf _0.5 Zr _0.5 O ₂ Thin Films via Novel Interface Layer Approach

Abstract Ferroelectric doped hafnium oxide (HfO 2 ) has emerged as CMOS‐compatible and scalable ferroelectric for next‐generation memory/in‐memory computing devices. However, its high coercive field (E c ) and limited endurance remain key obstacles. Here, a ≈25% reduction in E c from 3.3 to 2.5 MV/cm and an order of magnitude increase in endurance by implementing an ultrathin (≈2 nm) 5 at.% Sm‐doped HZO (HZSO) ionic conducting underlayer for HZO are shown. X‐ray photoelectron spectroscopy (XPS) results reveal the absence of redox effects during primary ferroelectric switching in HZSO, unlike in HZO. NEB calculations show that V O ‐rich HZSO lowers the switching barrier compared to that of HZO, which agrees with experimental results. Notably, these improvements are achieved in HZSO|HZO without compromising P r compared to HZO. This approach presents a new powerful route to engineering ferroelectric properties in doped HfO 2 , applicable to both epitaxial and polycrystalline films for future memory devices.