Anomalous Lattice Vibrations of Single- and Few-Layer MoS2
Anomalous Lattice Vibrations of Single- and Few-Layer MoS2
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DOI：
10.1021/nn1003937
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发表时间：
2010-05-01
期刊：
影响因子：
17.1
通讯作者：
Ryu, Sunmin
中科院分区：
文献类型：
--
作者：
Lee, Changgu;Yan, Hugen;Ryu, Sunmin
在 SiO2/Si 基底上剥离单层和几层厚度的二硫化钼 (MoS2)，并通过拉曼光谱进行表征。样品的S-Mo-S层数通过接触模式原子力显微镜独立测定。两种拉曼模式E-2g(1)和A(1g)表现出敏感的厚度依赖性，前者的频率随着厚度的增加而降低，后者的频率随着厚度的增加而增加。研究结果为以原子级精度确定层厚度提供了一种方便可靠的方法。频移的相反方向不能仅用范德华层间耦合来解释，而是归因于库仑相互作用和可能的堆叠引起的层内键合变化。这项工作例证了层状材料中结构参数从三维状态转变为二维状态的演变。
Molybdenum disulfide (MoS2) of single- and few-layer thickness was exfoliated on SiO2/Si substrate and characterized by Raman spectroscopy. The number of S-Mo-S layers of the samples was independently determined by contact-mode atomic force microscopy. Two Raman modes, E-2g(1) and A(1g), exhibited sensitive thickness dependence, with the frequency of the former decreasing and that of the latter increasing with thickness. The results provide a convenient and reliable means for determining layer thickness with atomic-level precision. The opposite direction of the frequency shifts, which cannot be explained solely by van der Waals interlayer coupling, is attributed to Coulombic interactions and possible stacking-induced changes of the intralayer bonding. This work exemplifies the evolution of structural parameters in layered materials in changing from the three-dimensional to the two-dimensional regime.