Coercive fields in ultrathin BaTiO3 capacitors

TL;DR

This study investigates the thickness-dependent coercive field in ultrathin BaTiO3 capacitors, revealing a nearly constant EC below 15 nm and a gradual decrease above, explained by a domain nuclei formation model and a shape crossover.

Contribution

It introduces a domain nuclei formation model to explain the thickness dependence of coercive fields in ultrathin BaTiO3 capacitors, highlighting a shape crossover at 15 nm.

Findings

EC is nearly independent of thickness below 15 nm.

A shape crossover from spheroid to cylinder occurs at ~15 nm.

The model aligns well with experimental data.

Abstract

Thickness-dependence of coercive field (EC) was investigated in ultrathin BaTiO3 capacitors with thicknesses (d) between 30 and 5 nm. The EC appears nearly independent of d below 15 nm, and decreases slowly as d increases above 15 nm. This behavior cannot be explained by extrinsic effects, such as interfacial passive layers or strain relaxation, nor by homogeneous domain models. Based on domain nuclei formation model, the observed EC behavior is explainable via a quantitative level. A crossover of domain shape from a half-prolate spheroid to a cylinder is also suggested at d~ 15 nm, exhibiting good agreement with experimental results.