Experimental demonstration of the suppression of optical phonon splitting in 2D materials by Raman spectroscopy
De Luca, Marta (Universität Basel. Departement Physik)
Cartoixà Soler, Xavier (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Indolese, David I. (Universität Basel. Departement Physik)
Martín Sánchez, Javier (Universidad de Oviedo. Departamento de Física)
Watanabe, Kenji (National Institute for Material Science)
Taniguchi, Takashi (National Institute for Materials Science)
Schönenberger, Christian (Universität Basel. Departement Physik)
Trotta, Rinaldo (Università degli Studi di Roma "La Sapienza". Dipartimento di Fisica)
Rurali, Riccardo (Institut de Ciència de Materials de Barcelona)
Zardo, Ilaria (University of Basel. Departement Physik)

Data:	2020
Resum:	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 (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.
Ajuts:	Agencia Estatal de Investigación MAT2017-90024-P Ministerio de Economía y Competitividad SEV-2015-0496 Agència de Gestió d'Ajuts Universitaris i de Recerca 2017/SGR-1506 Ministerio de Economía y Competitividad TEC2015-67462-C2-1-R Agencia Estatal de Investigación RTI2018-097876-B-C21 European Commission 785219 European Commission 787414 European Commission 679183
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, i la comunicació pública de l'obra, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original. No es permet la creació d'obres derivades.
Llengua:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Matèria:	DFT calculations ; H-BN ; Layer-by-layer stacking ; Non-analytical corrections ; Raman spectroscopy ; Transition metal dichalcogenides
Publicat a:	2D materials, Vol. 7, Num. 3 (May 2020) , art. 035017, ISSN 2053-1583

DOI: 10.1088/2053-1583/ab81b1

Postprint 25 p, 1.6 MB

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