Brightened emission of dark trions in transition-metal dichalcogenide monolayers

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Hauptverfasser: Jindal, V., Mourzidis, K., Balocchi, A., Robert, C., Li, P., Van Tuan, D., Lombez, L., Lagarde, D., Renucci, P., Taniguchi, T., Watanabe, K., Dery, H., Marie, X.
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Veröffentlicht: 2024
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author Jindal, V.
Mourzidis, K.
Balocchi, A.
Robert, C.
Li, P.
Van Tuan, D.
Lombez, L.
Lagarde, D.
Renucci, P.
Taniguchi, T.
Watanabe, K.
Dery, H.
Marie, X.
author_facet Jindal, V.
Mourzidis, K.
Balocchi, A.
Robert, C.
Li, P.
Van Tuan, D.
Lombez, L.
Lagarde, D.
Renucci, P.
Taniguchi, T.
Watanabe, K.
Dery, H.
Marie, X.
contents The optical emission spectra of semiconducting transition-metal dichalcogenide monolayers highlight fascinating recombination processes of charged excitons (trions). When charge tunable WSe$_2$ monolayers are moderately doped with electrons, a strong luminescence peak emerges just below the well-understood spectral lines associated with the recombination of negatively charged bright and dark trions. Despite previous investigations, its origin remains elusive. Here, we demonstrate that this luminescence peak is the result of electron-electron assisted recombination that brightens the dark trion emission. Supporting evidence for this second-order recombination process comes from identifying the brightened emission of positively charged dark trions when the monolayer is electrostatically doped with holes. Remarkably, the discovered hole-hole assisted luminescence peak emerges in the near infrared, about 500 meV below the well-studied spectral region of excitons and trions. In magneto-photoluminescence experiments we find that the $g$-factor of this new transition ($g$ = +4) has an opposite sign compared to the well-known $g$-factor of neutral or charged excitons. This allows us to propose a mechanism of brightening of the positively charged dark trion involving the $Γ$ valence band.
format Preprint
id arxiv_https___arxiv_org_abs_2406_02095
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Brightened emission of dark trions in transition-metal dichalcogenide monolayers
Jindal, V.
Mourzidis, K.
Balocchi, A.
Robert, C.
Li, P.
Van Tuan, D.
Lombez, L.
Lagarde, D.
Renucci, P.
Taniguchi, T.
Watanabe, K.
Dery, H.
Marie, X.
Mesoscale and Nanoscale Physics
The optical emission spectra of semiconducting transition-metal dichalcogenide monolayers highlight fascinating recombination processes of charged excitons (trions). When charge tunable WSe$_2$ monolayers are moderately doped with electrons, a strong luminescence peak emerges just below the well-understood spectral lines associated with the recombination of negatively charged bright and dark trions. Despite previous investigations, its origin remains elusive. Here, we demonstrate that this luminescence peak is the result of electron-electron assisted recombination that brightens the dark trion emission. Supporting evidence for this second-order recombination process comes from identifying the brightened emission of positively charged dark trions when the monolayer is electrostatically doped with holes. Remarkably, the discovered hole-hole assisted luminescence peak emerges in the near infrared, about 500 meV below the well-studied spectral region of excitons and trions. In magneto-photoluminescence experiments we find that the $g$-factor of this new transition ($g$ = +4) has an opposite sign compared to the well-known $g$-factor of neutral or charged excitons. This allows us to propose a mechanism of brightening of the positively charged dark trion involving the $Γ$ valence band.
title Brightened emission of dark trions in transition-metal dichalcogenide monolayers
topic Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2406.02095