Excitonic linewidth approaching the homogeneous limit in MoS2-based van der Waals heterostructures
By F. Cadiz, E. Courtade, C. Robert, Gang Wang, Y. Shen, H. Cai, Takashi Taniguchi, Kenji Watanabe, H. Carrère, D. Lagarde and 6 more. 2017
497 citations recorded by the source corpus.
The strong light-matter interaction and the valley selective optical selection rules make monolayer (ML) MoS[subscript 2] 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 MoSe[subscript 2] and WSe[subscript 2]. In this work, we show that encapsulation of ML MoS[subscript 2] 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 WS[subscript 2], WSe[subscript 2], and MoSe[subscript 2] 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.
Subfields: Atomic and Molecular Physics, and Optics, Electrical and Electronic Engineering, Materials Chemistry
View Paper: https://www.semanticscholar.org/paper/1fa5f0b34009ee3a53831fde884706e303040ac2
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Citations in the corpus
- Exciton physics and device application of two-dimensional transition metal dichalcogenide semiconductors (2018, background): “e determined by a broad peak corresponding to the bright 1s exciton transitions, at low temperatures a series of additional spectrally narrow resonances appears below the bright 1s excitons (Fig. 4a) [85]. These resonances can be ascribed to free excitons trapped in local potential wells. They vanis”
- Dark and bright exciton formation, thermalization, and photoluminescence in monolayer transition metal dichalcogenides (2017, result): “to a FHWM of 4 meV in linear spectroscopy), which is in excellent agreement with recent theoretical [43, 44] and experimental studies [45, 46].”