In-depth Understanding of Polarization Switching Kinetics in Polycrystalline Hf₀. ₅ Zr₀. ₅ O₂ Ferroelectric Thin Film: A Transition From NLS to KAI

To achieve deep insights into the polarization switching kinetics in ferroelectric Hf0. 5Zr0. 5O₂ (HZO), the intrinsic switching characteristics are measured accurately by using a novel pulse sequence to eliminate the charge trapping, polarization unsaturation and imprint effects. By NLS fittings, the average switching time and the concentration of pinning sites are extracted, with main focus on their dependences on the external electric field, the electrode size l and the temperature T. Although the average switching time shows weak dependence on T, , it decreases sharply with l scaling and sub-ns switching behavior is predicted at l 3. 89 m. More importantly, our observations intensely imply that a transition happens from NLS to KAI model when T is below 161K or l is approaching the grain size (10~30nm). This surprised but reasonable transition indicates that, as scaling the ferroelectric memory size or for operations under cryogenic temperatures, HZO ferroelectrics can switch much faster and more uniform.