Origin of Interstitial Doping Induced Coercive Field Reduction in Ferroelectric Hafnia

Abstract

Hafnia-based ferroelectrics hold promise for nonvolatile ferroelectric memory devices. However, the high coercive field required for polarization switching remains a prime obstacle to their practical applications. A notable reduction in coercive field has been achieved in ferroelectric Hf(Zr)${}_{1+x}$O${}_2$ films with interstitial Hf(Zr) dopants [Science 381, 558 (2023)], suggesting a less-explored strategy for coercive field optimization. Supported by density functional theory calculations, we demonstrate the $Pca{2}_1$ phase, with a moderate concentration of interstitial Hf dopants, serves as a minimal model to explain the experimental observations, rather than the originally assumed rhombohedral phase. Large-scale deep potential molecular dynamics simulations suggest that interstitial defects promote the polarization reversal by facilitating $Pbcn$-like mobile 180${}^{\circ }$ domain walls. A simple pre-poling treatment could reduce the switching field to less than 1 MV/cm and enable switching on a subnanosecond timescale. High-throughput calculations reveal a negative correlation between the switching barrier and dopant size and identify a few promising interstitial dopants for coercive field reduction.

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Cited by in corpus (1)

• Domain-Wall Mediated Polarization Switching in Ferroelectric AlScN: Strain Relief and Field-Dependent Dynamics