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Title: Inter-layer coupling induced valence band edge shift in mono- to few-layer MoS 2

In this study, recent progress in the synthesis of monolayer MoS 2, a two-dimensional direct band-gap semiconductor, is paving new pathways toward atomically thin electronics. Despite the large amount of literature, fundamental gaps remain in understanding electronic properties at the nanoscale. Here,we report a study of highly crystalline islands of MoS 2 grown via a refined chemical vapor deposition synthesis technique. Using high resolution scanning tunneling microscopy and spectroscopy (STM/STS), photoemission electron microscopy/spectroscopy (PEEM) and μ-ARPES we investigate the electronic properties of MoS 2 as a function of the number of layers at the nanoscale and show in-depth how the band gap is affected by a shift of the valence band edge as a function of the layer number. Green’s function based electronic structure calculations were carried out in order to shed light on the mechanism underlying the observed bandgap reduction with increasing thickness, and the role of the interfacial Sulphur atoms is clarified. Our study, which gives new insight into the variation of electronic properties of MoS 2 films with thickness bears directly on junction properties of MoS2, and thus impacts electronics application of MoS 2.
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [1] ;  [1] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [1] ;  [1] ;  [8] ;  [3] ;  [1]
  1. Temple Univ., Philadelphia, PA (United States)
  2. Tampere Univ. of Technology, Tampere (Finland)
  3. Northeastern Univ., Boston, MA (United States)
  4. National Tsing Hua Univ., Hsinchu (Taiwan)
  5. National Tsing Hua Univ., Hsinchu (Taiwan); Academic Sinica, Taipei (Taiwan)
  6. National Univ. of Singapore (Singapore)
  7. Helmholtz-Zentrum Berlin fur Materialien und Energie, Berlin (Germany)
  8. Temple Univ., Philadelphia, PA (United States); Northeastern Univ., Boston, MA (United States)
Publication Date:
Grant/Contract Number:
SC0012575; FG02-07ER46352
Type:
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 7; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Research Org:
Temple Univ., Philadelphia, PA (United States); Northeastern Univ., Boston, MA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; electronic properties and materials; two-dimensional materials
OSTI Identifier:
1347388