Lateral Size and Thickness Dependence in Ferroelectric Nanostructures Formed by Localized Domain Switching

TL;DR

This study uses simulations to explore how lateral size and thickness influence ferroelectric domain switching, revealing size-dependent switching mechanisms and the impact of fringing fields on domain behavior.

Contribution

It introduces a simulation-based analysis of size and thickness effects on ferroelectric domain switching, highlighting the role of fringing fields and switching mechanisms.

Findings

Switching mechanism shifts from 90° wedge nucleation to 180° rotation with decreasing thickness.

Smaller lateral sizes require higher voltages for switching, becoming nearly impossible at very small scales.

Fringing fields cause the switched region to extend beyond electrodes.

Abstract

Ferroelectric nanostructures can be formed by local switching of domains using techniques such as piezo-force microscopy (PFM). Understanding lateral size effects is important to determine the minimum feature size for writing ferroelectric nanostructures. To understand these lateral size effects, we use the time-dependent-Ginzburg-Landau equations to simulate localized switching of domains for a PFM type and parallel-plate capacitor configurations. Our investigations indicate that fringing electric fields lead to switching via 90 deg domain wedge nucleation for thicker films while at smaller thicknesses, the polarization switches directly by 180 deg rotations. The voltage required to switch the domain increases by decreasing the lateral size and at very small lateral sizes the coercive voltage becomes so large that it becomes virtually impossible to switch the domain. In all cases, the width of the switched region extends beyond the electrodes, due to fringing.