Raman Characterization of the Charge Density Wave Phase of 1T-TiSe2: From Bulk to Atomically Thin Layers

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• 作者：Dinh Loc DuongGihun Ryu ; Alexander Hoyer ; Chengtian Lin ; Marko Burghard ; Klaus Kern
• 刊名：ACS Nano
• 出版年：2017
• 出版时间：January 24, 2017
• 年：2017
• 卷：11
• 期：1
• 页码：1034-1040
• 全文大小：597K
• ISSN：1936-086X

文摘

Raman scattering is a powerful tool for investigating the vibrational properties of two-dimensional materials. Unlike the 2H phase of many transition metal dichalcogenides, the 1T phase of TiSe₂ features a Raman-active shearing and breathing mode, both of which shift toward lower energy with increasing number of layers. By systematically studying the Raman signal of 1T-TiSe₂ in dependence of the sheet thickness, we demonstrate that the charge density wave transition of this compound can be reliably determined from the temperature dependence of the peak position of the E_g mode near 136 cm^–1. The phase transition temperature is found to first increase with decreasing thickness of the sheets, followed by a decrease due to the effect of surface oxidation. The Raman spectroscopy-based method is expected to be applicable also to other 1T-phase transition metal dichalcogenides featuring a charge density wave transition and represents a valuable complement to electrical transport-based approaches.