Well separated trion and neutral excitons on superacid treated MoS2 monolayers

Fabian Cadiz*, Simon Tricard, Maxime Gay, Delphine Lagarde, Gang Wang, Cedric Robert, Pierre Renucci, Bernhard Urbaszek, Xavier Marie

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

53 Citations (Scopus)

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 MoS2 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 MoS2 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.

Original languageEnglish
Article number251106
JournalApplied Physics Letters
Volume108
Issue number25
DOIs
Publication statusPublished - 20 Jun 2016
Externally publishedYes

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