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Issue 14, 2015
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Large-area synthesis of monolayer WS2 and its ambient-sensitive photo-detecting performance

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Abstract

We demonstrate the synthesis of large-area monolayer WS2 films by chemical vapor deposition (CVD) and investigate their photoresponse properties by fabricating n-type field effect transistors (FETs) with Al as the ohmic contact. Our CVD-grown monolayer WS2 shows an electron mobility of 0.91 cm2 V−1 s−1 and an ON/OFF ratio of 106, indicating its comparable electronic properties to the mechanically exfoliated flake sample. In a vacuum, by applying a gate bias (60 V), the responsivity of the monolayer WS2 phototransistor can increase up to 18.8 mA W−1 and a decent sub-second level response time can be maintained. In contrast, in air, it shows a very fast response time of less than 4.5 ms, but at the cost of responsivity reduction to 0.2 μA W−1. Such a distinctive ambient-sensitive photo-detecting performance can be well-explained by the pronounced effect of charge-acceptor-like O2/H2O molecule adsorption/desorption on the photocarrier transport. Our CVD-grown high quality monolayer WS2 may pave the way for developing industrial-scale optoelectronic devices for photo-detecting and chemical sensing applications.

Graphical abstract: Large-area synthesis of monolayer WS2 and its ambient-sensitive photo-detecting performance

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Publication details

The article was received on 21 Feb 2015, accepted on 06 Mar 2015 and first published on 09 Mar 2015


Article type: Communication
DOI: 10.1039/C5NR01205H
Nanoscale, 2015,7, 5974-5980

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    Large-area synthesis of monolayer WS2 and its ambient-sensitive photo-detecting performance

    C. Lan, C. Li, Y. Yin and Y. Liu, Nanoscale, 2015, 7, 5974
    DOI: 10.1039/C5NR01205H

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