Operando Scanning Electron Microscopy Study of Support Interactions and Mechanisms of Salt-Assisted WS2 Growth

Operando Scanning Electron Microscopy Study of Support Interactions and Mechanisms of Salt-Assisted WS2 Growth

© 2025 The Authors. Published by American Chemical Society.

Bibliographische Detailangaben
Veröffentlicht in:Chemistry of materials : a publication of the American Chemical Society. - 1998. - 37(2025), 3 vom: 11. Feb., Seite 989-1000
1. Verfasser: Yang, Jinfeng (VerfasserIn)
Weitere Verfasser: Fan, Ye, Mizuta, Ryo, Rimmer, Max, Donoghue, Jack, Guan, Shaoliang, Haigh, Sarah J, Hofmann, Stephan
Format: Online-Aufsatz
Sprache:English
Veröffentlicht: 2025
Zugriff auf das übergeordnete Werk:Chemistry of materials : a publication of the American Chemical Society
Schlagworte:Journal Article
Beschreibung
Zusammenfassung:© 2025 The Authors. Published by American Chemical Society.
Salt enhanced chemical vapor deposition of WS2 and related 2D materials is widespread, and while many mechanisms including vapor-liquid-solid (VLS) mediated growth have been suggested, gaining a more detailed understanding remains challenging. We employ operando scanning electron microscopy to resolve the entire process of salt-assisted CVD of WS2, focusing on a model system of individual, small (<100 μm), sapphire supported sodium tungstate (Na2WO4) salt particles. We reveal support interactions that lead a salt particle to develop a lateral halo interface, driven by surface eutectic melting above 630 °C. This halo dictates the salt wetting as well as Na and W transport, and thus upon gaseous sulfur precursor exposure dominates the spatiotemporal WS2 nucleation and mono- and multilayer domain expansion kinetics, all of which we can directly track by secondary electron (SE) contrast with a conventional In-Lens SE detector. Unlike for a conventional VLS mechanism, large (>20 μm) monolayer WS2 formation does not involve the salt droplet directly attached to the growth facets, rather the salt droplet drives WS2 layer growth in the contiguous halo interface region with a continuous supply of W. We compare this to SiO2 and NaOH treated sapphire where corrosive surface roughening dictates the salt wetting, and critically discuss our findings in the context of the connected wider literature
Beschreibung:Date Revised 18.02.2025
published: Electronic-eCollection
Citation Status PubMed-not-MEDLINE
ISSN:0897-4756
DOI:10.1021/acs.chemmater.4c02603