title: Inter-Layer Coupling Induced Valence Band Edge Shift in Mono- to Few-Layer MoS2.
abstract: Recent progress in the synthesis of monolayer MoS2, 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 MoS2grown 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 MoS2as 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 MoS2films with thickness bears directly on junction properties of MoS2, and thus impacts electronics application of MoS2.
authors.affiliation: Physics Department, Temple University, Philadelphia PA 19122, USA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Trainer
authors.affiliation: Physics Department, Temple University, Philadelphia PA 19122, USA.
authors.forename: Aleksei V
authors.initials: AV
authors.lastname: Putilov
authors.affiliation: Physics Department, Temple University, Philadelphia PA 19122, USA.
authors.forename: Cinzia
authors.initials: C
authors.lastname: Di Giorgio
authors.affiliation: Department of Physics, Tampere University of Technology, Tampere, Finland.
authors.forename: Timo
authors.initials: T
authors.lastname: Saari
authors.affiliation: Physics Department, Northeastern University, Boston MA 02115, USA.
authors.forename: Baokai
authors.initials: B
authors.lastname: Wang
authors.affiliation: Physics Department, Temple University, Philadelphia PA 19122, USA.
authors.forename: Mattheus
authors.initials: M
authors.lastname: Wolak
authors.affiliation: Physics Department, Temple University, Philadelphia PA 19122, USA.
authors.forename: Ravini U
authors.initials: RU
authors.lastname: Chandrasena
authors.affiliation: Physics Department, Northeastern University, Boston MA 02115, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Lane
authors.affiliation: Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan.
authors.forename: Tay-Rong
authors.initials: TR
authors.lastname: Chang
authors.affiliation: Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan.|Institute of Physics, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Horng-Tay
authors.initials: HT
authors.lastname: Jeng
authors.affiliation: Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 117546 Singapore.|Department of Physics, National University of Singapore, 117546 Singapore.
authors.forename: Hsin
authors.initials: H
authors.lastname: Lin
authors.affiliation: Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein Straße 15, 12489 Berlin, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Kronast
authors.affiliation: Physics Department, Temple University, Philadelphia PA 19122, USA.
authors.forename: Alexander X
authors.initials: AX
authors.lastname: Gray
authors.affiliation: Physics Department, Temple University, Philadelphia PA 19122, USA.
authors.forename: Xiaoxing
authors.initials: X
authors.lastname: Xi
authors.affiliation: Department of Physics, Tampere University of Technology, Tampere, Finland.|Physics Department, Northeastern University, Boston MA 02115, USA.
authors.forename: Jouko
authors.initials: J
authors.lastname: Nieminen
authors.affiliation: Physics Department, Northeastern University, Boston MA 02115, USA.
authors.forename: Arun
authors.initials: A
authors.lastname: Bansil
authors.affiliation: Physics Department, Temple University, Philadelphia PA 19122, USA.
authors.forename: Maria
authors.initials: M
authors.lastname: Iavarone