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Electronic structure of a quasi-freestanding MoS2 monolayer

Cornell Affiliated Author(s)

Author

T. Eknapakul
P.D.C. King
M. Asakawa
P. Buaphet
R.-H. He
S.-K. Mo
H. Takagi
K.M. Shen
F. Baumberger
T. Sasagawa
S. Jungthawan
W. Meevasana

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 K̄ and K̄′ 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. © 2014 American Chemical Society.

Date Published

Journal

Nano Letters

Volume

14

Issue

3

Number of Pages

1312-1316,

URL

https://www.scopus.com/inward/record.uri?eid=2-s2.0-84896345049&doi=10.1021%2fnl4042824&partnerID=40&md5=d0aa92d25cacd1503947932d7c830c07

DOI

10.1021/nl4042824

Group (Lab)

Kyle Shen Group

Funding Source

207901
N00014-12-1-0791
EP/I031014/1
24224010
24340078

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