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Issue 34, 2018
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Scalable faceted voids with luminescent enhanced edges in WS2 monolayers

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A scalable approach is needed in the formation of atomically flat edges with specific terminations to enhance local properties for optoelectronic, nanophotonic and energy applications. We demonstrate point defect clustering-driven faceted void formations with luminescent enhanced edges in WS2 monolayers during large-scale CVD growth and controlled annealing. With the aid of aberration-corrected scanning transmission electron microscopy (AC-STEM) high angle annular dark field (HAADF) imaging, we probed atomic terminations of S and W to explain observed luminescence enhancement in alternate edges. Faceted void formation in monolayer WS2 was found to be sensitive to annealing temperature, time, gas environment and precursor supply. Our observations of areal coverage evolution over time revealed competition between monolayer WS2 growth and void formation at 850 °C. While the initial stage was dominated by monolayer growth, defect generation and void growth dominated at later stages and provided an optimum processing window for monolayer WS2 as well as faceted void growth. Growth of faceted voids not only followed the geometry of monolayer facets but also showed similar atomic terminations at the edges and thus enabled local manipulation of photoluminescence enhancement with an order of magnitude increase in intensity. The developed CVD processing enabled multi-fold increase in the luminescent active edge length through the formation of faceted voids within the WS2 monolayer.

Graphical abstract: Scalable faceted voids with luminescent enhanced edges in WS2 monolayers

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Publication details

The article was received on 18 Mar 2018, accepted on 07 Aug 2018 and first published on 08 Aug 2018

Article type: Paper
DOI: 10.1039/C8NR02246A
Citation: Nanoscale, 2018,10, 16321-16331

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    Scalable faceted voids with luminescent enhanced edges in WS2 monolayers

    P. Kumar, D. Chatterjee, T. Maeda, A. Roy, K. Kaneko and V. Balakrishnan, Nanoscale, 2018, 10, 16321
    DOI: 10.1039/C8NR02246A

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