Layer-dependent resonant Raman scattering of a few layer MoS2
Layer-dependent resonant Raman scattering of a few layer MoS2
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DOI：
10.1002/jrs.4147
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发表时间：
2013-01-01
影响因子：
2.5
通讯作者：
Rao, C. N. R.
中科院分区：
文献类型：
--
作者：
Chakraborty, Biswanath;Matte, H. S. S. Ramakrishna;Rao, C. N. R.
我们报告的共振拉曼散射的二硫化钼层，包括单层，双，四层和七层，显示出强烈的依赖于层的厚度。块状的间接带隙MoS 2变成单层形式的直接带隙半导体。新的拉曼模式中看到的光谱中的单层和少层的二硫化钼样品是不存在的散装。在二层、四层和七层样品中出现了与230 cm（-1）相近的拉曼模。这种模式归因于布里渊区M点（LA（M））处的纵向声学声子分支。在179 cm（-1）附近的模式显示了少层样品的非对称特征。这种不对称性是由LA（M）分支沿着G-M方向的色散所解释的。在455 cm（-1）附近的最强光谱区域显示出峰位和相对强度随层的变化。在510和645 cm（-1）之间的高能区，出现了显著的新拉曼谱带，其强度随层数而变化。因此，共振拉曼光谱作为一种有前途的非侵入性技术，以准确地估计厚度的二硫化钼层下降到几个原子厚。版权所有（C）2012约翰威利父子有限公司
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.