A grease for domain walls motion in HfO₂-based ferroelectrics

A large coercive fieldE_Cof HfO₂based ferroelectric devices poses critical performance issues in their applications as ferroelectric memories and ferroelectric field effect transistors. A new design to reduceE_Cby fabricating nanolaminate Hf_0.5Zr_0.5O₂/ZrO₂(HZZ) thin films is used, followed by an ensuing annealing process at a comparatively high temperature 700 °C. High-resolution electron microscopy imaging detects tetragonal-like domain walls between orthorhombic polar regions. These walls decrease the potential barrier of polarization reversal in HfO₂based films compared to the conventional domain walls with a single non-polar spacer, causing about a 40% decrease inE_C. Capacitance versus electric field measurements on HZZ thin film uncovered a substantial increase of dielectric permittivity near theE_Ccompared to the conventional Hf_0.5Zr_0.5O₂thin film, justifying the higher mobility of domain walls in the developed HZZ film. The tetragonal-like regions served as grease easing the movement of the domain wall and reducingE_C.