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Electronic Structure of a Quasi-Freestanding MoS2 Monolayer

Eknapakul, T.
King, P. D. C.
Asakawa, M.
Buaphet, P.
He, R.-H.
Mo, S.-K.
Takagi, H.
Shen, K. M.
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Published in Nano letters. 2014, vol. 14, no. 3, p. 1312-1316
Abstract Several transition-metal dichalcogenides exhibit a striking crossover from indirect to direct band gap semiconductors as they are thinned down to a single monolayer. Here, we demonstrate how an electronic structure characteristic of the isolated monolayer can be created at the surface of a bulk MoS2 crystal. This is achieved by intercalating potassium in the interlayer van der Waals gap, expanding its size while simultaneously doping electrons into the conduction band. Our angle-resolved photoemission measurements reveal resulting electron pockets centered at the K̅ and K′ points of the Brillouin zone, providing the first momentum-resolved measurements of how the conduction band dispersions evolve to yield an approximately direct band gap of ∼1.8 eV in quasi-freestanding monolayer MoS2. As well as validating previous theoretical proposals, this establishes a novel methodology for manipulating electronic structure in transition-metal dichalcogenides, opening a new route for the generation of large-area quasi-freestanding monolayers for future fundamental study and use in practical applications.
Keywords Molybdenum disulfide (MoS2)Transition metal dichalcogenides (TMD)Layered semiconductorElectronic structureAngle-resolved photoemissionVan der Waals expansion
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Research group Groupe Baumberger
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EKNAPAKUL, T. et al. Electronic Structure of a Quasi-Freestanding MoS2 Monolayer. In: Nano Letters, 2014, vol. 14, n° 3, p. 1312-1316. doi: 10.1021/nl4042824 https://archive-ouverte.unige.ch/unige:42082

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Deposited on : 2014-11-21

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