A grease for domain walls motion in HfO ₂ -based ferroelectrics

Abstract

Abstract A large coercive field E C of HfO 2 based ferroelectric devices poses critical performance issues in their applications as ferroelectric memories and ferroelectric field effect transistors. A new design to reduce E C by fabricating nanolaminate Hf 0.5 Zr 0.5 O 2 /ZrO 2 (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 HfO 2 based films compared to the conventional domain walls with a single non-polar spacer, causing about a 40% decrease in E C . Capacitance versus electric field measurements on HZZ thin film uncovered a substantial increase of dielectric permittivity near the E C compared to the conventional Hf 0.5 Zr 0.5 O 2 thin 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 reducing E C .