title: Electrical Tuning of Exciton Binding Energies in Monolayer WS_{2}.
abstract: We demonstrate continuous tuning of the exciton binding energy in monolayer WS_{2} by means of an externally applied voltage in a field-effect transistor device. Using optical spectroscopy, we monitor the ground and excited excitonic states as a function of gate voltage and track the evolution of the quasiparticle band gap. The observed decrease of the exciton binding energy over the range of about 100 meV, accompanied by the renormalization of the quasiparticle band gap, is associated with screening of the Coulomb interaction by the electrically injected free charge carriers at densities up to 8×10^{12} cm^{-2}. Complete ionization of the excitons due to the electrical doping is estimated to occur at a carrier density of several 10^{13} cm^{-2}.
authors.affiliation: Departments of Physics and Electrical Engineering, Columbia University, New York, New York 10027, USA.
authors.forename: Alexey
authors.initials: A
authors.lastname: Chernikov
authors.affiliation: Departments of Physics and Electrical Engineering, Columbia University, New York, New York 10027, USA.|Department of Mechanical Engineering, Columbia University, New York, New York 10027, USA.|Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors.forename: Arend M
authors.initials: AM
authors.lastname: van der Zande
authors.affiliation: Departments of Physics and Electrical Engineering, Columbia University, New York, New York 10027, USA.
authors.forename: Heather M
authors.initials: HM
authors.lastname: Hill
authors.affiliation: Departments of Physics and Electrical Engineering, Columbia University, New York, New York 10027, USA.
authors.forename: Albert F
authors.initials: AF
authors.lastname: Rigosi
authors.affiliation: Departments of Physics and Electrical Engineering, Columbia University, New York, New York 10027, USA.|Department of Physics and Materials Sciences Center, Philipps-Universität Marburg, Marburg 35032, Germany.
authors.forename: Ajanth
authors.initials: A
authors.lastname: Velauthapillai
authors.affiliation: Department of Mechanical Engineering, Columbia University, New York, New York 10027, USA.
authors.forename: James
authors.initials: J
authors.lastname: Hone
authors.affiliation: Departments of Physics and Electrical Engineering, Columbia University, New York, New York 10027, USA.|Department of Applied Physics, Stanford University, Stanford, California 94305, USA.|SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Tony F
authors.initials: TF
authors.lastname: Heinz