Exposing the trion's fine structure by controlling the carrier concentration in hBN-encapsulated MoS${}_2$

Abstract

Atomically thin materials, like semiconducting transition metal dichalcogenides, are highly sensitive to the environment. This opens up an opportunity to externally control their properties by changing their surroundings. In this work, high-quality van der Waals heterostructures assembled from hBN-encapsulated monolayer MoS${}_2$ are studied with the aid of photoluminescence, photoluminescence excitation, and reflectance contrast experiments. We demonstrate that carrier concentration in MoS${}_2$ monolayers, arising from charge transfer from impurities in the substrate, can be significantly tuned within one order of magnitude by the modification of the bottom hBN flake thickness. The studied structures, characterized by spectral lines approaching the narrow homogeneously broadened limit enabled observations of subtle optical and spin-valley properties of excitonic complexes. Our results allowed us to resolve three optically-active negatively charged excitons in MoS${}_2$ monolayers, which are assigned to the intravalley singlet, intervalley singlet, and intervalley triplet states.

arXiv comment9 pages, 4 figures

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Cited by in corpus (12)

• Trions in MoS${}_2$ are quantum superpositions of intra- and intervalley spin states
• Probing Dark Excitons in Monolayer MoS${}_2$ by NonLinear Two-Photon Spectroscopy
• The effect of dielectric environment on the brightening of neutral and charged dark excitons in WSe${}_2$ monolayer
• Quantum light generation with ultra-high spatial resolution in 2D semiconductors via ultra-low energy electron irradiation
• Proximity-enhanced valley Zeeman splitting at the WS${}_2$/graphene interface
• Raman scattering excitation in monolayers of semiconducting transition metal dichalcogenides
• Electrostatic control of the trion fine structure in transition metal dichalcogenide monolayers
• Energy shifts and broadening of excitonic resonances in electrostatically-doped semiconductors
• Extremely high excitonic $g$-factors in 2D crystals by alloy-induced admixing of band states
• Magneto-Excitonic Duality From Monolayer to Trilayer CrSBr
• Electrically modulated light-emitting diodes driven by resonant and antiresonant tunneling between Cr${}_2$Ge${}_2$Te${}_6$ electrodes
• Efficient valley polarization of charged excitons and resident carriers in MoS2 monolayers by optical pumping