Analysis of Polarization Switching in HZO/ZrO2 (HZZ) Nanolaminates based on Sub-lattice Phase-field Model

HZO/ZrO 2 (HZZ) nanolaminates have attracted attention as a promising strategy for obtaining ultra-low equivalent oxide thickness (EOT) [1]. HZZ nanolaminates have a structure of alternate thin layers of HZO and ZrO 2 with o- (ferroelectric or FE) and t-phase (anti-FE or AFE), respectively (Fig. 1a) [2]. HZZ displays an intermediate polarization-voltage (P-V) characteristic of FE and AFE, referred to as a broken loop. Atomic-scale sub-lattice model of HZO attributes this effect to morphotropic phase boundary (MPB) formation (Fig. 1b) [3]. However, the device-scale model with multi-phase co-existence is yet to be explored. In this work, we propose a phase-field model based on sub-lattices to explain the unique characteristics of HZZ nanolaminates. We investigate the underlying polarization switching mechanisms for HZZ and compare them to those in HZO and ZrO 2 .