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Understanding metal organic chemical vapour deposition of monolayer WS2 : the enhancing role of Au substrate for simple organosulfur precursors

DOI: 10.1039/D0NR06459A DOI Help

Authors: Ye Fan (University of Cambridge) , Kenichi Nakanishi (University of Cambridge) , Vlad P. Veigang-radulescu (University of Cambridge) , Ryo Mizuta (University of Cambridge) , J. Callum Stewart (University of Cambridge) , Jack E. N. Swallow (University of Oxford) , Alice E. Dearle (University of Cambridge) , Oliver J. Burton (University of Cambridge) , Jack A. Alexander-webber (University of Cambridge) , Pilar Ferrer (Diamond Light Source) , Georg Held (Diamond Light Source) , Barry Brennan (National Physical Laboratory) , Andrew J. Pollard (National Physical Laboratory) , Robert S Weatherup (University of Cambridge) , Stephan Hofmann (University of Cambridge)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nanoscale , VOL 7

State: Published (Approved)
Published: October 2020
Diamond Proposal Number(s): 22123

Open Access Open Access

Abstract: We find that the use of Au substrate allows fast, self-limited WS2 monolayer growth using a simple sequential exposure pattern of low cost, low toxicity precursors, namely tungsten hexacarbonyl and dimethylsulfide (DMS). We use this model reaction system to fingerprint the technologically important metal organic chemical vapour deposition process by operando X-ray photoelectron spectroscopy (XPS) to address the current lack of understanding of the underlying fundamental growth mechanisms for WS2 and related transition metal dichalcogenides. Au effectively promotes the sulfidation of W with simple organosulfides, enabling WS2 growth with low DMS pressure (<1 mbar) and a suppression of carbon contamination of as-grown WS2, which to date has been a major challenge with this precursor chemistry. Full WS2 coverage can be achieved by one exposure cycle of 10 minutes at 700 °C. We discuss our findings in the wider context of previous literature on heterogeneous catalysis, 2D crystal growth, and overlapping process technologies such as atomic layer deposition (ALD) and direct metal conversion, linking to future integrated manufacturing processes for transition metal dichalcogenide layers.

Subject Areas: Chemistry, Materials


Instruments: B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS

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