Raman Shifts in Electron-Irradiated Monolayer MoS2

We report how the presence of electron-beam-induced sulfur vacancies affects first-order Raman modes and correlate the effects with the evolution of the in situ transmission-electron microscopy two-terminal conductivity of monolayer MoS2 under electron irradiation. We observe a red-shift in the E′ R...

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Published inACS nano Vol. 10; no. 4; pp. 4134 - 4142
Main Authors Parkin, William M, Balan, Adrian, Liang, Liangbo, Das, Paul Masih, Lamparski, Michael, Naylor, Carl H, Rodríguez-Manzo, Julio A, Johnson, A. T. Charlie, Meunier, Vincent, Drndić, Marija
Format Journal Article
LanguageEnglish
Published United States American Chemical Society 26.04.2016
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ISSN1936-0851
1936-086X
1936-086X
DOI10.1021/acsnano.5b07388

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Summary:We report how the presence of electron-beam-induced sulfur vacancies affects first-order Raman modes and correlate the effects with the evolution of the in situ transmission-electron microscopy two-terminal conductivity of monolayer MoS2 under electron irradiation. We observe a red-shift in the E′ Raman peak and a less pronounced blue-shift in the A′1 peak with increasing electron dose. Using energy-dispersive X-ray spectroscopy and selected-area electron diffraction, we show that irradiation causes partial removal of sulfur and correlate the dependence of the Raman peak shifts with S vacancy density (a few %). This allows us to quantitatively correlate the frequency shifts with vacancy concentration, as rationalized by first-principles density functional theory calculations. In situ device current measurements show an exponential decrease in channel current upon irradiation. Our analysis demonstrates that the observed frequency shifts are intrinsic properties of the defective systems and that Raman spectroscopy can be used as a quantitative diagnostic tool to characterize MoS2-based transport channels.
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USDOE Office of Science (SC)
AC05-00OR22725
W. M. Parkin, A. Balan, and L. Liang have contributed equally.
ISSN:1936-0851
1936-086X
1936-086X
DOI:10.1021/acsnano.5b07388