Anomalous Lattice Vibrations of Single- and Few-Layer MoS2

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• 作者：Changgu Lee ; Hugen Yan ; Louis E. Brus ; Tony F. Heinz ; James Hone ; Sunmin Ryu
• 刊名：ACS Nano
• 出版年：2010
• 出版时间：May 25, 2010
• 年：2010
• 卷：4
• 期：5
• 页码：2695-2700
• 全文大小：337K
• 年卷期：0
• ISSN：1936-086X

文摘

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, E¹_2g 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.