Multi-domain Polarization Switching in Hf0.5Zr0.5O2-Dielectric Stack: The Role of Dielectric Thickness

TL;DR

This study explores how dielectric thickness influences polarization switching in ferroelectric-dielectric stacks, revealing multi-domain behaviors and their effects on polarization and hysteresis characteristics through experiments and simulations.

Contribution

It demonstrates the impact of dielectric thickness on polarization switching mechanisms and hysteresis in FE-DE stacks, highlighting multi-domain effects beyond single-domain models.

Findings

Increased TDE decreases remnant polarization.

Larger TDE leads to more reverse domains and higher coercive voltage.

Multi-domain switching explains charge-voltage hysteresis features.

Abstract

We investigate the polarization switching mechanism in ferroelectric-dielectric (FE-DE) stacks and its dependence on the dielectric thickness (TDE). We fabricate HZO-Al2O3 (FE-DE) stack and experimentally demonstrate a decrease in remnant polarization and an increase in coercive voltage of the FE-DE stack with an increase in TDE. Using phase-field simulations, we show that an increase in TDE results in a larger number of reverse domains in the FE layer to suppress the depolarization field, which leads to a decrease in remanent polarization and an increase in coercive voltage. Further, the applied voltage-driven polarization switching suggests domain-nucleation dominant characteristics for low TDE, and domain-wall motion-induced behavior for higher TDE. In addition, we show that the hysteretic charge-voltage characteristics of the FE layer in the FE-DE stack exhibit a negative slope region due to the multi-domain polarization switching in the FE layer. Based on our analysis, the trends in charge-voltage characteristics of the FE-DE stack with respect to different TDE (which are out of the scope of single-domain models) can be described well with multi-domain polarization switching mechanisms.