Reducing Coercive Field and Improving Endurance in Ferroelectric Epitaxial Hf0.5Zr0.5O2 Thin Films via Novel Interface Layer Approach.

Ferroelectric doped hafnium oxide (HfO2) has emerged as CMOS-compatible and scalable ferroelectric for next-generation memory/in-memory computing devices. However, its high coercive field (Ec) and limited endurance remain key obstacles. Here, a ≈25% reduction in Ec 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 VO-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 Pr compared to HZO. This approach presents a new powerful route to engineering ferroelectric properties in doped HfO2, applicable to both epitaxial and polycrystalline films for future memory devices.