Experimental demonstration of the suppression of optical phonon splitting in 2D materials by Raman spectroscopy
- 20 March 2020
- journal article
- research article
- Published by IOP Publishing in 2D Materials
- Vol. 7 (3), 035017
- https://doi.org/10.1088/2053-1583/ab81b1
Abstract
Raman spectroscopy is one of the most extended experimental techniques to investigate thin-layered 2D materials. For a complete understanding and modeling of the Raman spectrum of a novel 2D material, it is often necessary to combine the experimental investigation to density-functional-theory calculations. We provide the experimental proof of the fundamentally different behavior of polar 2D vs 3D systems regarding the effect of the dipole−dipole interactions, which in 2D systems ultimately lead to the absence of optical phonons splitting, otherwise present in 3D materials. We demonstrate that non-analytical corrections (NACs) should not be applied to properly model the Raman spectra of few-layered 2D materials, such as WSe2 and h-BN, corroborating recent theoretical predictions [Nano Lett. 2017, 17 (6), 3758-3763]. Our findings are supported by measurements performed on tilted samples that allow increasing the component of photon momenta in the plane of the flake, thus unambiguously setting the direction of an eventual NAC. We also investigate the influence of the parity of the number of layers and of the type of layer-by-layer stacking on the effect of NACs on the Raman spectra.Keywords
Funding Information
- Horizon 2020 Framework Programme (679183, 785219, 787414, GrapheneCore2 785219, PA-18-ACB17-29)
- Ministry of Science, Innovation and Universities (RTI2018-097876-B-C21)
- Core Research for Evolutional Science and Technology (JPMJCR15F3)
- Ministry of Education, Culture, Sports, Science and Technology
- Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung (200021_165784, PZ00P2_179801)
- Japan Science and Technology Agency
- Ministerio de Economía, Industria y Competitividad, Gobierno de España (FEDER-MAT2017-90024-P, RYC2018-026196-I, SEV-2015-0496, TEC2015-67462-C2-1-R)
- Generalitat de Catalunya (2017 SGR 1506)
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