Article (Scientific journals)
Raman imaging of twist angle variations in twisted bilayer graphene at intermediate angles
Schäpers, A.; Sonntag, J.; Valerius, L. et al.
2022In 2D Mater., 9 (4), p. 045009
Peer reviewed
 

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Keywords :
twisted bilayer graphene; Raman spectroscopy; electronic structure
Abstract :
[en] Van der Waals layered materials with well-defined twist angles between the crystal lattices of individual layers have attracted increasing attention due to the emergence of unexpected material properties. As many properties critically depend on the exact twist angle and its spatial homogeneity, there is a need for a fast and non-invasive characterization technique of the local twist angle, to be applied preferably right after stacking. We demonstrate that confocal Raman spectroscopy can be utilized to spatially map the twist angle in stacked bilayer graphene for angles between 6.5 and 8 degree when using a green excitation laser. The twist angles can directly be extracted from the moiré superlattice-activated Raman scattering process of the transverse acoustic (TA) phonon mode. Furthermore, we show that the width of the TA Raman peak contains valuable information on spatial twist angle variations on length scales below the laser spot size of ∼500 nm.
Disciplines :
Physics
Author, co-author :
Schäpers, A.;  Rheinisch - Westfälische Technische Hochschule Aachen - RWTH
Sonntag, J.;  Rheinisch - Westfälische Technische Hochschule Aachen - RWTH
Valerius, L.;  Rheinisch - Westfälische Technische Hochschule Aachen - RWTH
Pestka, B.;  Rheinisch - Westfälische Technische Hochschule Aachen - RWTH
Strasdas, J.;  Rheinisch - Westfälische Technische Hochschule Aachen - RWTH
Watanabe, K.;  Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
Taniguchi, T.;  International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
Wirtz, Ludger ;  University of Luxembourg > Faculty of Science, Technology and Medicine (FSTM) > Department of Physics and Materials Science (DPHYMS)
Morgenstern, M.;  Rheinisch - Westfälische Technische Hochschule Aachen - RWTH
Beschoten, B.;  Rheinisch - Westfälische Technische Hochschule Aachen - RWTH
Dolleman, R. J.;  Rheinisch - Westfälische Technische Hochschule Aachen - RWTH
Stampfer, C.;  Rheinisch - Westfälische Technische Hochschule Aachen - RWTH
External co-authors :
yes
Language :
English
Title :
Raman imaging of twist angle variations in twisted bilayer graphene at intermediate angles
Publication date :
2022
Journal title :
2D Mater.
ISSN :
2053-1583
Publisher :
IOP Publishing
Volume :
9
Issue :
4
Pages :
045009
Peer reviewed :
Peer reviewed
Focus Area :
Physics and Materials Science
FnR Project :
FNR13376969 - Anharmonic And Exchange Interactions In Phonon Spectra, 2018 (01/01/2020-30/06/2024) - Ludger Wirtz
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since 18 November 2022

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