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Parzefall, Philipp ; Holler, Johannes ; Scheuck, Marten ; Beer, Andreas ; Lin, Kai-Qiang ; Peng, Bo ; Monserrat, Bartomeu ; Nagler, Philipp ; Kempf, Michael ; Korn, Tobias ; Schüller, Christian

Moiré phonons in twisted MoSe2–WSe2 heterobilayers and their correlation with interlayer excitons

Parzefall, Philipp , Holler, Johannes , Scheuck, Marten, Beer, Andreas, Lin, Kai-Qiang , Peng, Bo , Monserrat, Bartomeu, Nagler, Philipp, Kempf, Michael, Korn, Tobias and Schüller, Christian (2021) Moiré phonons in twisted MoSe2–WSe2 heterobilayers and their correlation with interlayer excitons. 2D Materials 8 (3), 035030.

Date of publication of this fulltext: 16 Aug 2021 11:35
Article
DOI to cite this document: 10.5283/epub.47854


Abstract

We report about the investigation of twisted MoSe2 homo- and MoSe2-WSe2 heterobilayers by means of low-frequency Raman spectroscopy (LFRS) and low-temperature micro photoluminescence (mu PL). In room-temperature LFRS experiments on both, twisted MoSe2 homobilayers and twisted MoSe2-WSe2 heterobilayers, we observe moire phonons, i.e. folded acoustic phonon modes due to the moire superlattice. In ...

We report about the investigation of twisted MoSe2 homo- and MoSe2-WSe2 heterobilayers by means of low-frequency Raman spectroscopy (LFRS) and low-temperature micro photoluminescence (mu PL). In room-temperature LFRS experiments on both, twisted MoSe2 homobilayers and twisted MoSe2-WSe2 heterobilayers, we observe moire phonons, i.e. folded acoustic phonon modes due to the moire superlattice. In the heterobilayers, we can identify moire phonons of both materials, MoSe2 and WSe2. While the twist angles for the homobilayers are relatively precisely known from the applied tear-and-stack preparation method, the twist angles of the heterobilayers have to be determined via second-harmonic-generation microscopy on monolayer regions of the samples, which has significant uncertainties. We show that by the moire phonons of the heterobilayers, the relative twist angles can be determined on a local scale with much higher precision. We apply our technique for the investigation of a large area H-type (twist angle theta = 60 degrees + delta) MoSe2-WSe2 heterobilayer. These investigations show that spatial regions, which can be identified to be atomically reconstructed (i.e. delta = 0 degrees) by the observation of an interlayer shear mode in LFRS experiments, exhibit a strong, momentum-allowed interlayer-exciton signal in low-temperature mu PL. On the contrary, regions, where moire phonons are observed, i.e. which can be identified to be rigidly twisted by a misalignment angle in the range of 5 degrees less than or similar to vertical bar delta vertical bar less than or similar to 6 degrees, exhibit no significant interlayer-exciton signals.



Involved Institutions


Details

Item typeArticle
Journal or Publication Title2D Materials
Publisher:IOP PUBLISHING LTD
Open Access Type:IOP (Hybrid)
Place of Publication:BRISTOL
Volume:8
Number of Issue or Book Chapter:3
Page Range:035030
Date5 May 2021
InstitutionsPhysics > Institute of Experimental and Applied Physics > Chair Professor Lupton > Group Christian Schüller
Identification Number
ValueType
10.1088/2053-1583/abf98eDOI
KeywordsDER-WAALS HETEROSTRUCTURES; RAMAN-SCATTERING; MONOLAYER MOS2; moire phonons; moire superlattice; Raman scattering; transition-metal dichalcogenides; interlayer excitons
Dewey Decimal Classification500 Science > 530 Physics
StatusPublished
RefereedYes, this version has been refereed
Created at the University of RegensburgYes
URN of the UB Regensburgurn:nbn:de:bvb:355-epub-478541
Item ID47854

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