Photoinduced Patterning of Oxygen Vacancies to Promote the Ferroelectric Phase of $\mathrm{Hf_{0.5}Zr_{0.5}O_2}$

TL;DR

This study demonstrates that laser-induced photo-reduction of oxygen vacancies in Hf0.5Zr0.5O2 thin films enhances their ferroelectric phase and piezoelectric response, offering a spatially controlled post-synthesis modification method.

Contribution

It introduces a novel, low-energy laser technique to selectively reduce oxygen vacancies and promote ferroelectric phase formation in Hf0.5Zr0.5O2 films.

Findings

Laser doses of 0.02-0.77 mJ/μm^2 effectively reduce oxygen vacancies.

Photoinduced vacancy reduction increases ferroelectric phase fraction.

Enhanced piezoelectric response observed via piezoresponse force microscopy.

Abstract

Photoinduced reductions in the oxygen vacancy concentration were leveraged to increase the ferroelectric phase fraction of $\mathrm{Hf_{0.5}Zr_{0.5}O_2}$ (HZO) thin-films. Modest ($\sim 0.02-0.77~\mathrm{mJ/\mu m^2}$) laser doses of visible light (488 nm, 2.54 eV) spatially patterned the concentration of oxygen vacancies as monitored by photoluminescence imaging. Local, tip-based, near-field, nanoFTIR measurements showed that the photoinduced oxygen vacancy concentration reduction promoted formation of the ferroelectric phase (space group $Pca2_1$) resulting in an increase in the piezoelectric response measured by piezoresponse force microscopy. Photoinduced vacancy tailoring provides, therefore, a spatially prescriptive, post-synthesis, and low-entry method to modify phase in \hfo-based materials.