Optimizing the Ferroelectric Performance of Hf0.5Zr0.5O2 Epitaxial Film by La0.67Sr0.33MnO3 Capping Layer

Hafnium-oxide-based ferroelectrics have garnered considerable research interest, primarily for their robust ferroelectricity at the nanoscale and their high compatibility with complementary metal-oxide-semiconductors processes. However, the impact of electrodes on the ferroelectric properties of hafnium-oxide layer, particularly that of top electrodes, is not yet fully understood even in the simplest capacitor geometry. In this study, the La0.67Sr0.33MnO3/Hf0.5Zr0.5O2 (LSMO/HZO) epitaxial heterostructure is utilized as a model system to conduct a systematic comparative study on ferroelectricity between the LSMO/HZO (H-LS) bilayer and LSMO/HZO/LSMO (LS-H-LS) trilayer samples. In comparison to the H-LS sample, the LS-H-LS sample exhibits a more uniform polar domain configuration and larger ferroelectric polarization. Moreover, the LS-H-LS sample exhibits significant improvements in leakage, endurance, and retention. These substantial enhancements in ferroelectricity are likely due to interfacial stress imposed by the LSMO capping layer and its capacity to accommodate extra oxygen vacancies. These results underscore the pivotal role of oxide-based top electrodes in determining the ferroelectricity of hafnium-oxide-based heterostructures, providing crucial insights for optimizing the performance of innovative ferroelectric devices.