Intrinsic Phonon Bands in High-Quality Monolayer T′ Molybdenum Ditelluride

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• 作者：Shao-Yu Chen ; Carl H. Naylor ; Thomas Goldstein ; A. T. Charlie Johnson ; Jun Yan
• 刊名：ACS Nano
• 出版年：2017
• 出版时间：January 24, 2017
• 年：2017
• 卷：11
• 期：1
• 页码：814-820
• 全文大小：563K
• ISSN：1936-086X

文摘

The topologically nontrivial and chemically functional distorted octahedral (T′) transition-metal dichalcogenides (TMDCs) are a type of layered semimetal that has attracted significant recent attention. However, the properties of monolayer (1L) T′-TMDC, a fundamental unit of the system, are still largely unknown due to rapid sample degradation in air. Here we report that well-protected 1L CVD T′-MoTe₂ exhibits sharp and robust intrinsic Raman bands, with intensities about 1 order of magnitude stronger than those from bulk T′-MoTe₂. The high-quality samples enabled us to reveal the set of all nine even-parity zone-center optical phonons, providing reliable fingerprints for the previously elusive crystal. By performing light polarization and crystal orientation resolved scattering analysis, we can effectively distinguish the intrinsic modes from Te-metalloid-like modes A (∼122 cm^–1) and B (∼141 cm^–1), which are related to the sample degradation. Our studies offer a powerful nondestructive method for assessing sample quality and for monitoring sample degradation in situ, representing a solid advance in understanding the fundamental properties of 1L-T′-TMDCs.