Intrinsic Phonon Bands in High-Quality Monolayer T′ Molybdenum Ditelluride
Intrinsic Phonon Bands in High-Quality Monolayer T′ Molybdenum Ditelluride
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DOI：
10.1021/acsnano.6b07260
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发表时间：
2017-01-01
期刊：
影响因子：
17.1
通讯作者：
Yan, Jun
中科院分区：
文献类型：
--
作者：
Chen, Shao-Yu;Naylor, Carl H.;Yan, Jun
拓扑结构非平凡且化学功能扭曲的八面体（T'）过渡金属二硫属化物（TMDC）是一种层状半金属，最近引起了人们的广泛关注。然而，由于样品在空气中快速降解，单层 (1L) T'-TMDC（该系统的基本单元）的特性仍然很大程度上未知。在这里，我们报告说，受到良好保护的 1L CVD T'-MoTe2 表现出尖锐而强大的本征拉曼谱带，其强度比块状 T'-MoTe2 强约 1 个数量级。高质量的样品使我们能够揭示所有九个偶宇称区中心光学声子的集合，为以前难以捉摸的晶体提供可靠的指纹。通过光偏振和晶体取向分辨散射分析，我们可以有效地区分与样品降解有关的类Te类金属模式A（类似于122 cm(-1)）和B（类似于141 cm(-1)）的本征模式。我们的研究提供了一种强大的无损方法来评估样品质量和监测样品原位降解，代表着在理解 1L-T'-TMDC 基本特性方面取得了坚实的进展。
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 (similar to 122 cm(-1)) and B (similar to 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.