Ultrahigh remanent polarization of Ce-doped HfO2 ferroelectric thin films through strain engineering

Abstract

Hafnium oxide (HfO₂)-based ferroelectric materials have been widely applied in logic and memory devices due to their favorable ferroelectric and dielectric properties. However, the weak ferroelectric polarization of pure HfO₂ limits its application potential in advanced ferroelectric devices. Here, an ultrahigh remanent polarization is successfully achieved in the Ce-doped HfO₂ films through a chemical negative strain due to the biaxial strain engineering strategy. The Ce-doped HfO₂ films with regulated ions concentrations are fabricated on crystallographic-oriented substrates, and the effects of substrate-induced strain on the film growth were systematically investigated. Notably, the Ce-doped HfO₂ films grown on (011) oriented substrates exhibit an excellent remanent polarization (2P_r = 102.1 µC/cm²), representing the highest value reported for HfO₂-based ferroelectrics, along with the outstanding fatigue resistance (<10% degradation after 10⁷ switching cycles). This work provides a novel strategy for developing high-performance HfO₂-based ferroelectric materials through strain engineering, laying a critical foundation for their applications in non-volatile memory technologies.