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In Operando Optical Tracking of Oxygen Vacancy Migration and Phase Change in few Nanometers Ferroelectric HZO Memories

Published version
Peer-reviewed

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Authors

Jan, A 
Rembert, T 
Taper, S 
Symonowicz, J 

Abstract

jats:titleAbstract</jats:title>jats:pFerroelectric materials offer a low‐energy, high‐speed alternative to conventional logic and memory circuitry. Hafnia‐based films have achieved single‐digit nm ferroelectricity, enabling further device miniaturization. However, they can exhibit nonideal behavior, specifically wake‐up and fatigue effects, leading to unpredictable performance variation over consecutive electronic switching cycles, preventing large‐scale commercialization. The origins are still under debate. Using plasmon‐enhanced spectroscopy, a non‐destructive technique sensitive to <1% oxygen vacancy variation, phase changes, and single switching cycle resolution, the first real‐time in operando nanoscale direct tracking of oxygen vacancy migration in 5 nm hafnium zirconium oxide during a pre‐wake‐up stage is provided. It is shown that the pre‐wake‐up leads to a structural phase change from monoclinic to orthorhombic phase, which further determines the device wake‐up. Further migration of oxygen ions in the phase changed material is then observed, producing device fatigue. These results provide a comprehensive explanation for the wake‐up and fatigue with Raman, photoluminescence and darkfield spectroscopy, combined with density functional theory and finite‐difference time‐domain simulations.</jats:p>

Description

Funder: Gianna Angelopoulos Programme for Science, Technology, and Innovation


Funder: Cambridge Trust; Id: http://dx.doi.org/10.13039/501100003343

Keywords

DF spectroscopy, fatigue, HZO ultra-thin FeRAM, oxygen vacancies, phase changes, Raman and PL, wake-up

Journal Title

Advanced Functional Materials

Conference Name

Journal ISSN

1616-301X
1616-3028

Volume Title

Publisher

Wiley
Sponsorship
EPSRC (EP/T012218/1)
European Commission Horizon 2020 (H2020) ERC (882929)
EPSRC (EP/T517847/1)
Isaac Newton Trust (20.40(e))
Royal Society (RGS\R1\221262)
MRC (MR/V023926/1)
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