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Effects of Precursor Pre-treatment on the Vapor Deposition of WS2 Monolayer

Abstract

Transition metal oxide powders have been widely used as the growth precursors for monolayer transition metal dichalcogenides (TMDCs) in chemical vapor deposition (CVD). It has been proposed that the metal oxide precursors in gas phase undergo a two-step reaction during the CVD growth, where the transition metal sub-oxides are likely formed first and then the sulfurization of these sub-oxides leads to the formation of TMDCs. However, the effects of stoichiometry of transition metal oxide precursors on the growth of TMDC monolayers have not been studied yet. In this contribution, we report the critical role of WO3 precursor pre-annealing process on the growth of WS2 monolayer. Besides, several WO3 precursors with different types of oxygen vacancies have also been prepared and determined by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) as well as the density functional theory calculation. Among all the non-stoichiometric WO3 precursors, the thermal annealed WO3 powder exhibits the highest oxygen vacancies concentration and produces WS2 monolayers with significantly improved quality in term of lateral size, density, and crystallinity. Our comprehensive study suggests that the chemical composition of transition metal oxide precursors would be fundamentally critical for the growth of large-area and high-quality WS2 monolayers, which further pave the way for revealing their intrinsic properties and unique applications.

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Publication details

The article was received on 17 Sep 2018, accepted on 05 Nov 2018 and first published on 05 Nov 2018


Article type: Communication
DOI: 10.1039/C8NA00212F
Citation: Nanoscale Adv., 2019, Accepted Manuscript
  • Open access: Creative Commons BY-NC license
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    Effects of Precursor Pre-treatment on the Vapor Deposition of WS2 Monolayer

    M. E. Pam, Y. shi, J. Hu, X. Zhao, S. Huang, X. Gong, J. Dan, D. Geng, S. J. Pennycook, R. Ang and H. Y. Yang, Nanoscale Adv., 2019, Accepted Manuscript , DOI: 10.1039/C8NA00212F

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