Nanoscale Heterogeneities in Monolayer MoSe2 Revealed by Correlated Scanning Probe Microscopy and Tip-Enhanced Raman Spectroscopy

Published

December 26, 2017

Author(s)

Albert Davydov, Sergiy Krylyuk, Payam Taheri, Kirby K. Smithe, Andrey V. Krayev, Connor S. Bailey, Hye R. Lee, Eilam Yalon, Ozgur B. Aslan, Miguel M. Rojo, Tony F. Heinz, Eric Pop

Abstract

Understanding growth, grain boundaries (GBs), and defects of emerging two-dimensional (2D) materials is key to enabling their future applications. For quick, non-destructive metrology, many studies rely on confocal Raman spectroscopy, whose spatial resolution is constrained by the dif- fraction limit. Here we use tip-enhanced Raman spectroscopy (TERS) for the first time on syn- thetic MoSe2 monolayers, combining it with other scanning probe microscopy (SPM) techniques, all with sub- 20 nm spatial resolution. We uncover strong nanoscale heterogeneities in the Raman spectra of MoSe2 transferred to gold substrates, [one near 240 cm-1 (A1’), and others near 287 cm 1 (E’), 340 cm-1, and 995 cm-1], which are not observable with common confocal techniques and appear to imply the presence of nanoscale domains of MoO3. We also observe strong tip-enhanced photoluminescence (TEPL), with signal almost an order of magnitude higher than the far-field PL. Combining TERS with other SPM techniques, we find that GBs can cut into larger domains of MoSe2, and that carrier densities are higher at GBs than away from them.

Citation

ACS Applied Nano Materials

Volume

1

Pub Type

Journals

Keywords

2D Materials, Tip-Enhanced Raman Spectroscopy, Scanning Probe Microscopy, Chemical Vapor Deposition, MoSe2, Heterogeneity

Citation

Davydov, A. , Krylyuk, S. , Taheri, P. , Smithe, K. , Krayev, A. , Bailey, C. , Lee, H. , Yalon, E. , Aslan, O. , Rojo, M. , Heinz, T. and Pop, E. (2017), Nanoscale Heterogeneities in Monolayer MoSe2 Revealed by Correlated Scanning Probe Microscopy and Tip-Enhanced Raman Spectroscopy, ACS Applied Nano Materials (Accessed April 25, 2024)