Layer-dependent resonant Raman scattering of a few layer MoS2

Chakraborty, Biswanath and Matte, Ramakrishna HSS and Sood, AK and Rao, CNR (2013) Layer-dependent resonant Raman scattering of a few layer MoS2. In: JOURNAL OF RAMAN SPECTROSCOPY, 44 (1). pp. 92-96.

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Abstract

We report resonant Raman scattering of MoS2 layers comprising of single, bi, four and seven layers, showing a strong dependence on the layer thickness. Indirect band gap MoS2 in bulk becomes a direct band gap semiconductor in the monolayer form. New Raman modes are seen in the spectra of single- and few-layer MoS2 samples which are absent in the bulk. The Raman mode at similar to 230 cm(-1) appears for two, four and seven layers. This mode has been attributed to the longitudinal acoustic phonon branch at the M point (LA(M)) of the Brillouin zone. The mode at similar to 179 cm(-1) shows asymmetric character for a few-layer sample. The asymmetry is explained by the dispersion of the LA(M) branch along the G-M direction. The most intense spectral region near 455 cm(-1) shows a layer-dependent variation of peak positions and relative intensities. The high energy region between 510 and 645 cm(-1) is marked by the appearance of prominent new Raman bands, varying in intensity with layer numbers. Resonant Raman spectroscopy thus serves as a promising non invasive technique to accurately estimate the thickness of MoS2 layers down to a few atoms thick. Copyright (C) 2012 John Wiley & Sons, Ltd.

Item Type:	Journal Article
Publication:	JOURNAL OF RAMAN SPECTROSCOPY
Publisher:	WILEY-BLACKWELL
Additional Information:	Copyright for this article belongs to WILEY-BLACKWELL, USA
Keywords:	MoS2;monolayer;bilayer;resonant Raman
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	06 Mar 2013 11:03
Last Modified:	06 Mar 2013 11:03
URI:	http://eprints.iisc.ac.in/id/eprint/45958

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