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Excitonic linewidth approaching the homogeneous limit in MoS<inf>2</inf>-based van der Waals heterostructures

Cadiz, F and Courtade, E and Robert, C and Wang, G and Shen, Y and Cai, H and Taniguchi, T and Watanabe, K and Carrere, H and Lagarde, D and Manca, M and Amand, T and Renucci, P and Tongay, S and Marie, X and Urbaszek, B (2017) Excitonic linewidth approaching the homogeneous limit in MoS<inf>2</inf>-based van der Waals heterostructures. Physical Review X, 7. ISSN 2160-3308

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The strong light-matter interaction and the valley selective optical selection rules make monolayer (ML) MoS an exciting 2D material for fundamental physics and optoelectronics applications. But, so far, optical transition linewidths even at low temperature are typically as large as a few tens of meVand contain homogeneous and inhomogeneous contributions. This prevented in-depth studies, in contrast to the bettercharacterized ML materials MoSe and WSe . In this work, we show that encapsulation of ML MoS in hexagonal boron nitride can efficiently suppress the inhomogeneous contribution to the exciton linewidth, as we measure in photoluminescence and reflectivity a FWHM down to 2 meVat T = 4 K. Narrow optical transition linewidths are also observed in encapsulated WS , WSe , and MoSe MLs. This indicates that surface protection and substrate flatness are key ingredients for obtaining stable, high-quality samples. Among the new possibilities offered by the well-defined optical transitions, we measure the homogeneous broadening induced by the interaction with phonons in temperature-dependent experiments. We uncover new information on spin and valley physics and present the rotation of valley coherence in applied magnetic fields perpendicular to the ML. 2 2 2 2 2 2 2

Item Type: Article
Divisions: Div B > Solid State Electronics and Nanoscale Science
Depositing User: Cron Job
Date Deposited: 15 Sep 2017 20:09
Last Modified: 15 Apr 2021 06:50
DOI: 10.1103/PhysRevX.7.021026