Experimental demonstration of the suppression of optical phonon splitting in 2D materials by Raman spectroscopy

De Luca, Marta and Cartoixà, Xavier and Indolese, David I. and Martín-Sánchez, Javier and Watanabe, Kenji and Taniguchi, Takashi and Schoenenberger, Christian and Trotta, Rinaldo and Rurali, Riccardo and Zardo, Ilaria. (2020) Experimental demonstration of the suppression of optical phonon splitting in 2D materials by Raman spectroscopy. 2D Materials, 7 (3). 035017.

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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 WSe 2 and h-BN, corroborating recent theoretical predictions (Sohier et al 2017 Nano Lett. 17 3758-63). 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.
Faculties and Departments:05 Faculty of Science > Departement Physik > Physik > Experimental Material Physics (Zardo)
UniBasel Contributors:Zardo, Ilaria and De Luca, Marta and Indolese, David and Schönenberger, Christian
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:IOP Publishing
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:07 Apr 2021 10:31
Deposited On:07 Apr 2021 10:30

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