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Title: Well separated trion and neutral excitons on superacid treated MoS{sub 2} monolayers

Abstract

Developments in optoelectronics and spin-optronics based on transition metal dichalcogenide monolayers (MLs) need materials with efficient optical emission and well-defined transition energies. In as-exfoliated MoS{sub 2} MLs, the photoluminescence (PL) spectra even at low temperature consist typically of broad, overlapping contributions from neutral, charged excitons (trions) and localized states. Here, we show that in superacid treated MoS{sub 2} MLs, the PL intensity increases by up to 60 times at room temperature. The neutral and charged exciton transitions are spectrally well separated in PL and reflectivity at T = 4 K, with linewidth for the neutral exciton of 15 meV, but both transitions have similar intensities compared to the ones in as-exfoliated MLs at the same temperature. Time resolved experiments uncover picoseconds recombination dynamics analyzed separately for charged and neutral exciton emissions. Using the chiral interband selection rules, we demonstrate optically induced valley polarization for both complexes and valley coherence for only the neutral exciton.

Authors:
; ; ; ; ; ; ; ;  [1]
  1. Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Av. Rangueil, 31077 Toulouse (France)
Publication Date:
OSTI Identifier:
22590640
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 108; Journal Issue: 25; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; EXCITONS; LINE WIDTHS; MILLI EV RANGE; MOLYBDENUM SULFIDES; PHOTOLUMINESCENCE; RECOMBINATION; REFLECTIVITY; SELECTION RULES; SILICON OXIDES; SPECTRA; TEMPERATURE RANGE 0273-0400 K; TIME RESOLUTION; TRANSITION ELEMENTS

Citation Formats

Cadiz, Fabian, E-mail: cadiz@insa-toulouse.fr, Tricard, Simon, Gay, Maxime, Lagarde, Delphine, Wang, Gang, Robert, Cedric, Renucci, Pierre, Urbaszek, Bernhard, and Marie, Xavier. Well separated trion and neutral excitons on superacid treated MoS{sub 2} monolayers. United States: N. p., 2016. Web. doi:10.1063/1.4954837.
Cadiz, Fabian, E-mail: cadiz@insa-toulouse.fr, Tricard, Simon, Gay, Maxime, Lagarde, Delphine, Wang, Gang, Robert, Cedric, Renucci, Pierre, Urbaszek, Bernhard, & Marie, Xavier. Well separated trion and neutral excitons on superacid treated MoS{sub 2} monolayers. United States. doi:10.1063/1.4954837.
Cadiz, Fabian, E-mail: cadiz@insa-toulouse.fr, Tricard, Simon, Gay, Maxime, Lagarde, Delphine, Wang, Gang, Robert, Cedric, Renucci, Pierre, Urbaszek, Bernhard, and Marie, Xavier. 2016. "Well separated trion and neutral excitons on superacid treated MoS{sub 2} monolayers". United States. doi:10.1063/1.4954837.
@article{osti_22590640,
title = {Well separated trion and neutral excitons on superacid treated MoS{sub 2} monolayers},
author = {Cadiz, Fabian, E-mail: cadiz@insa-toulouse.fr and Tricard, Simon and Gay, Maxime and Lagarde, Delphine and Wang, Gang and Robert, Cedric and Renucci, Pierre and Urbaszek, Bernhard and Marie, Xavier},
abstractNote = {Developments in optoelectronics and spin-optronics based on transition metal dichalcogenide monolayers (MLs) need materials with efficient optical emission and well-defined transition energies. In as-exfoliated MoS{sub 2} MLs, the photoluminescence (PL) spectra even at low temperature consist typically of broad, overlapping contributions from neutral, charged excitons (trions) and localized states. Here, we show that in superacid treated MoS{sub 2} MLs, the PL intensity increases by up to 60 times at room temperature. The neutral and charged exciton transitions are spectrally well separated in PL and reflectivity at T = 4 K, with linewidth for the neutral exciton of 15 meV, but both transitions have similar intensities compared to the ones in as-exfoliated MLs at the same temperature. Time resolved experiments uncover picoseconds recombination dynamics analyzed separately for charged and neutral exciton emissions. Using the chiral interband selection rules, we demonstrate optically induced valley polarization for both complexes and valley coherence for only the neutral exciton.},
doi = {10.1063/1.4954837},
journal = {Applied Physics Letters},
number = 25,
volume = 108,
place = {United States},
year = 2016,
month = 6
}
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