@article{842d5d254190477283848b1a75b8d79d,
title = "Raman Shifts in Electron-Irradiated Monolayer MoS2",
abstract = "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.",
author = "Parkin, {William M.} and Adrian Balan and Liangbo Liang and Das, {Paul Masih} and Michael Lamparski and Naylor, {Carl H.} and Rodr{\'i}guez-Manzo, {Julio A.} and Johnson, {A. T.Charlie} and Vincent Meunier and Marija Drndi{\'c}",
note = "Funding Information: The authors thank M. Puster for assistance with experiments. This work was supported by NIH Grant R21HG004767, NIH Grant R21HG007856, and NSF Grant NSF EFRI-1542707. We gratefully acknowledge use of the TEM in the NSF-MRSEC electron microscopy facility at the University of Pennsylvania and the use of the AC-TEM facility at Lehigh University. We thank D. Yates at the University of Pennsylvania and R. Keyse at Lehigh University for their assistance with electron microscopy. The theoretical work at Rensselaer Polytechnic Institute (RPI) was supported by New York State under NYSTAR program C080117 and the Office of Naval Research. The computations were performed using the resources of the Center for Computational Innovation at RPI. L.L. was supported by a Eugene P. Wigner Fellowship at Oak Ridge National Laboratory and also acknowledges work at the Center for Nanophase Materials Sciences, a DOE Office of Science User Facility. C.H.N. and A.T.C.J. acknowledge support from UES/Air Force Research Laboratory and NSF PFI AIR ENG-1312202. NSF Major Research Instrumentation Grant DMR-0923245 is acknowledged. Publisher Copyright: {\textcopyright} 2016 American Chemical Society.",
year = "2016",
month = apr,
day = "26",
doi = "10.1021/acsnano.5b07388",
language = "English (US)",
volume = "10",
pages = "4134--4142",
journal = "ACS nano",
issn = "1936-0851",
publisher = "American Chemical Society",
number = "4",
}