Exciton Up-conversion in Transition Metal Dichalcogenide Monolayers

ORAL

Abstract

The optical properties of Transition Metal Dichalcogenide (TMD) monolayers are governed by robust excitons. We have systematically investigated the excited exciton states by photoluminescence up-conversion spectroscopy in high quality MoS2, MoSe2, MoTe2 and WSe2 monolayers (MLs) encapsulated in hBN [1]. The excitation laser is tuned into resonance with the A:1s exciton ground state transition, and we observe for all the investigated MLs clear emission of excited exciton states (A:2s, A:3s…) up to 450 meV above the laser energy. The optical transitions are further investigated by reflectivity, photoluminescence excitation, and resonant Raman scattering, confirming their origin as excited excitonic states. We interpret the efficient up-conversion process as the consequence of exciton-exciton interactions where one of the excitons is annihilated while the second exciton acquires large extra energy. This mechanism is expected to be quite weak because it should satisfy both energy and momentum conservation laws. However our model calculations suggest an efficient exciton-exciton (Auger) scattering mechanism specific to TMD monolayers involving an excited conduction band, thus generating high-energy excitons with small wave vectors.
[1] B. Han et al, PRX 8, 031073 (2018)

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Presenters

  • Xavier Marie

    CNRS/INSA, LPCNO, Institut National des Sciences Appliquees de Toulouse, LPCNO, Institut National des Sciences Appliquées de Toulouse, INSA/CNRS, INSA Toulouse

Authors

  • Xavier Marie

    CNRS/INSA, LPCNO, Institut National des Sciences Appliquees de Toulouse, LPCNO, Institut National des Sciences Appliquées de Toulouse, INSA/CNRS, INSA Toulouse

  • Bo Han

    CNRS/INSA, INSA/CNRS

  • Cedric Robert

    CNRS/INSA, INSA/CNRS

  • Mickael Glazov

    Ioffe Institute

  • Leonid Golub

    Ioffe Institute

  • Marco Manca

    INSA/CNRS

  • Shivangi Shree

    INSA/CNRS, CNRS/INSA

  • Emmanuel Courtade

    INSA/CNRS, INSA Toulouse, CNRS/INSA

  • Pierre Renucci

    LPCNO, Institut National des Sciences Appliquees de Toulouse, INSA/CNRS

  • Bernhard Urbaszek

    CNRS/INSA, LPCNO, Institut National des Sciences Appliquees de Toulouse, INSA/CNRS, INSA Toulouse

  • Thierry Amand

    LPCNO, Institut National des Sciences Appliquees de Toulouse, INSA/CNRS

  • Takashi Taniguchi

    National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305 0044, Japan, National Institute for Materials Science, Advanced Materials Laboratory, National Institute for Materials Science, , 1-1 Namiki, Tsukuba 305-0044, Japan, National Institute for Material Science, 1-1 Namiki, Tsukuba 305-0044, National Institute of Materials Science, NIMS, Japan, Advanced Materials Laboratory, NIMS, National Institute for Materials Science, Tsukuba, Japan, Advanced Materials Laboratory, National Institute for Materials Science, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0044, Japan, National Institute for Materials Science (NIMS), NIMS Tsukuba, NIMS, National Institute for Material Science, National Institute for Materials Science, Japan, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Japan, National Institute for Materials Science , Japan, Advanced Materials Laboratory, National Institute for Materials Science, Japan, Advanced Materials Laboratory, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan, National Institute for Materials Science, Tsukuba, Ibaraki 305- 0044, Japan, National Institute for Material Science - Japan, National Institute for Materials Science, Namiki Tsukuba Ibaraki, Japan, National Institute of Material Science, Advanced Material Lab, NIMS, Advanced Materials Laboratory, National Institute for Materials Science, Tsukuba, Japan, Advanced Materials Laboratory, National Institute for Materials Science, Tsukuba, Ibaraki, Japan, National Institute for Materials Science, Tsukuba, 1-1 Namiki, Tsukuba, National Institute for Materials Science, NIMS/Tsukuba, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044 Japan, National Institute for Materials Science, Namiki, 305-0044, Japan, National Institute for Material Science, Japan, Advanced Materials Laboratory, NIMS, Japan, Advanced Materials Labaratory, National Institute for Materials Science, National Institute of Material Science, 1-1 Namiki, Tsukuba, Ibaraki 205-0044, Japan, National Institute of Materials Science, Japan

  • Kenji Watanabe

    National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305 0044, Japan, Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan, National Institute for Materials Science, Advanced Materials Laboratory, National Institute for Materials Science, , 1-1 Namiki, Tsukuba 305-0044, Japan, National Institute for Material Science, 1-1 Namiki, Tsukuba 305-0044, National Institute of Materials Science, NIMS, Japan, Advanced Materials Laboratory, NIMS, National Institute for Materials Science, Tsukuba, Japan, National Institute for Materials Science, Japan, Advanced Materials Laboratory, National Institute for Materials Science, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0044, Japan, National Institute for Materials Science (NIMS), NIMS Tsukuba, National Institute for Materials Science (Japan), NIMS, National Institute for Material Science, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Japan, National Institute for Materials Science , Japan, National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan., Advanced Materials Laboratory, National Institute for Materials Science, Japan, Advanced Materials Laboratory, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan, National Institute for Materials Science, Tsukuba, Ibaraki 305- 0044, Japan, National Institute for Material Science - Japan, National Institute for Materials Science, Namiki Tsukuba Ibaraki, Japan, National Institute of Material Science, Advanced Material Lab, NIMS, Advanced Materials Laboratory, National Institute for Materials Science, Tsukuba, Japan, Advanced Materials Laboratory, National Institute for Materials Science, Tsukuba, Ibaraki, Japan, National Institute for Materials Science, Tsukuba, 1-1 Namiki, Tsukuba, National Institute for Materials Science, NIMS/Tsukuba, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044 Japan, National Institute for Materials Science, Namiki, 305-0044, Japan, National Institute for Material Science, Japan, Advanced Materials Laboratory, NIMS, Japan, Columbia University, Advanced Materials Labaratory, National Institute for Materials Science, National Institute of Material Science, 1-1 Namiki, Tsukuba, Ibaraki 205-0044, Japan, National Institute of Materials Science, Japan