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

Journal Article · Mon Jun 20 00:00:00 EDT 2016 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.4954837· OSTI ID:22590640

Cadiz, Fabian; Tricard, Simon; Gay, Maxime; Lagarde, Delphine; Wang, Gang; Robert, Cedric; Renucci, Pierre; Urbaszek, Bernhard; Marie, Xavier ^[1]

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1. Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Av. Rangueil, 31077 Toulouse (France)

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.

• OSTI ID: 22590640
• Journal Information: Applied Physics Letters, Vol. 108, Issue 25; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

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