Excitonic Linewidth Approaching the Homogeneous Limit in MoS 2 -Based van der Waals Heterostructures - INSA Toulouse - Institut National des Sciences Appliquées de Toulouse Access content directly
Journal Articles Physical Review X Year : 2017

Excitonic Linewidth Approaching the Homogeneous Limit in MoS 2 -Based van der Waals Heterostructures

K. Watanabe
Thierry Amand

Abstract

The strong light-matter interaction and the valley selective optical selection rules make monolayer (ML) MoS2 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 meV and contain homogeneous and inhomogeneous contributions. This prevented in-depth studies, in contrast to the better-characterized ML materials MoSe2 and WSe2. In this work, we show that encapsulation of ML MoS2 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 meV at T=4  K. Narrow optical transition linewidths are also observed in encapsulated WS2, WSe2, and MoSe2 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.
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Dates and versions

hal-02053910 , version 1 (01-03-2019)

Identifiers

  • HAL Id : hal-02053910 , version 1

Cite

Fabian Cadiz, Emmanuel Courtade, Cédric Robert, Gang Wang, Y. Shen, et al.. Excitonic Linewidth Approaching the Homogeneous Limit in MoS 2 -Based van der Waals Heterostructures. Physical Review X, 2017, 7 (2). ⟨hal-02053910⟩
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