Direct exciton emission from atomically thin transition metal dichalcogenide heterostructures near the lifetime limit

Jakob Wierzbowski, Julian Klein, Florian Sigger, Christian Straubinger, Malte Kremser, Takashi Taniguchi, Kenji Watanabe, Ursula Wurstbauer, Alexander W. Holleitner, Michael Kaniber, Kai Müller, Jonathan J. Finley

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128 Scopus citations

Abstract

We demonstrate the reduction of the inhomogeneous linewidth of the free excitons in atomically thin transition metal dichalcogenides (TMDCs) MoSe2, WSe2 and MoS2 by encapsulation within few nanometre thick hBN. Encapsulation is shown to result in a significant reduction of the 10 K excitonic linewidths down to 3.5 meV for n-MoSe2, 5.0 meV for p-WSe2 and 4.8 meV for n-MoS2. Evidence is obtained that the hBN environment effectively lowers the Fermi level since the relative spectral weight shifts towards the neutral exciton emission in n-doped TMDCs and towards charged exciton emission in p-doped TMDCs. Moreover, we find that fully encapsulated MoS2 shows resolvable exciton and trion emission even after high power density excitation in contrast to non-encapsulated materials. Our findings suggest that encapsulation of mechanically exfoliated few-monolayer TMDCs within nanometre thick hBN dramatically enhances optical quality, producing ultra-narrow linewidths that approach the homogeneous limit.

Original languageEnglish
Article number12383
JournalScientific Reports
Volume7
Issue number1
DOIs
StatePublished - 1 Dec 2017

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