期刊
2D MATERIALS
卷 3, 期 3, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/2053-1583/3/3/034004
关键词
tungsten ditelluride; WTe2; Raman spectroscopy; polarization; orientation; thickness
资金
- Center for Advanced Soft Electronics under the Global Frontier Research Program of the MSIP [2011-0031630]
- National Research Foundation of Korea - Korea government (MSIP) [2015R1A2A2A01006992]
- National Research Foundation of Korea [2015R1A2A2A01006992, 2015H1A2A1033060, 22A20151113064] Funding Source: Korea Institute of Science & Technology Information (KISTI), National Science & Technology Information Service (NTIS)
Orthorhombic tungsten ditelluride (WTe2), with a distorted 1T structure, exhibits a large magnetoresistance that depends on the orientation, and its electrical characteristics changes from semimetallic to insulating as the thickness decreases. Through polarized Raman spectroscopy in combination with transmission electron diffraction, we establish a reliable method to determine the thickness and crystallographic orientation of few-layer WTe2. The Raman spectrum shows a pronounced dependence on the polarization of the excitation laser. We found that the separation between two Raman peaks at similar to 90 cm(-1) and at 80-86 cm(-1), depending on thickness, is a reliable fingerprint for determination of the thickness. For determination of the crystallographic orientation, the polarization dependence of the A(1) modes, measured with the 632.8 nm excitation, turns out to be the most reliable. We also discovered that the polarization behaviors of some of the Raman peaks depend on the excitation wavelength as well as thickness, indicating a close interplay between the band structure and anisotropic Raman scattering cross section.
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