Parzefall, Philipp and Holler, Johannes and Scheuck, Marten and Beer, Andreas and Lin, Kai-Qiang and Peng, Bo and Monserrat, Bartomeu and Nagler, Philipp and Kempf, Michael and Korn, Tobias and Schueller, Christian (2021) Moire phonons in twisted MoSe2-WSe2 heterobilayers and their correlation with interlayer excitons. 2D MATERIALS, 8 (3): 035030. ISSN 2053-1583
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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.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | DER-WAALS HETEROSTRUCTURES; RAMAN-SCATTERING; MONOLAYER MOS2; moire phonons; moire superlattice; Raman scattering; transition-metal dichalcogenides; interlayer excitons |
| Subjects: | 500 Science > 530 Physics |
| Divisions: | Physics > Institute of Experimental and Applied Physics > Chair Professor Lupton > Group Christian Schüller |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 18 Aug 2022 08:53 |
| Last Modified: | 18 Aug 2022 08:53 |
| URI: | https://pred.uni-regensburg.de/id/eprint/46716 |
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