title: Probing the role of interlayer coupling and coulomb interactions on electronic structure in few-layer MoSe₂ nanostructures.
abstract: Despite the weak nature of interlayer forces in transition metal dichalcogenide (TMD) materials, their properties are highly dependent on the number of layers in the few-layer two-dimensional (2D) limit. Here, we present a combined scanning tunneling microscopy/spectroscopy and GW theoretical study of the electronic structure of high quality single- and few-layer MoSe2 grown on bilayer graphene. We find that the electronic (quasiparticle) bandgap, a fundamental parameter for transport and optical phenomena, decreases by nearly one electronvolt when going from one layer to three due to interlayer coupling and screening effects. Our results paint a clear picture of the evolution of the electronic wave function hybridization in the valleys of both the valence and conduction bands as the number of layers is changed. This demonstrates the importance of layer number and electron-electron interactions on van der Waals heterostructures and helps to clarify how their electronic properties might be tuned in future 2D nanodevices.
authors.affiliation: †Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States.
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Bradley
authors.affiliation: †Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States.
authors.forename: Miguel M
authors.initials: MM
authors.lastname: Ugeda
authors.affiliation: †Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States.|‡Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
authors.forename: Felipe H
authors.initials: FH
authors.lastname: da Jornada
authors.affiliation: †Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States.|‡Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
authors.forename: Diana Y
authors.initials: DY
authors.lastname: Qiu
authors.affiliation: †Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States.|§State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Ruan
authors.affiliation: ∥Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.|⊥Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: †Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States.|‡Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Wickenburg
authors.affiliation: †Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States.
authors.forename: Alexander
authors.initials: A
authors.lastname: Riss
authors.affiliation: †Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States.|∇Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.
authors.forename: Jiong
authors.initials: J
authors.lastname: Lu
authors.affiliation: ∥Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
authors.forename: Sung-Kwan
authors.initials: SK
authors.lastname: Mo
authors.affiliation: ∥Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
authors.forename: Zahid
authors.initials: Z
authors.lastname: Hussain
authors.affiliation: ⊥Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States.|■Geballe Laboratory for Advanced Materials, Departments of Physics and Applied Physics, Stanford University, Stanford, California 94305, United States.
authors.forename: Zhi-Xun
authors.initials: ZX
authors.lastname: Shen
authors.affiliation: †Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States.|‡Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
authors.forename: Steven G
authors.initials: SG
authors.lastname: Louie
authors.affiliation: †Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States.|‡Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.|○Kavli Energy NanoSciences Institute, University of California Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Crommie
mesh_terms: D018011:Chalcogens / Q000737:chemistry; D004579:Electron Transport; D008422:Materials Testing / Q000379:methods; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D015336:Molecular Probe Techniques; D008982:Molybdenum / Q000737:chemistry*; D012643:Selenium / Q000737:chemistry*; D055672:Static Electricity
chemical_list: D018011:Chalcogens; D008982:Molybdenum; D012643:Selenium
keywords: Coulomb interaction; STM/STS; graphene; quasiparticle bandgap; screening; transition metal dichalcogenide