Electrical Tuning of Exciton Binding Energies in Monolayer WS_{2}

Alexey Chernikov; Arend M van der Zande; Heather M Hill; Albert F Rigosi; Ajanth Velauthapillai; James Hone; Tony F Heinz

doi:10.1103/PhysRevLett.115.126802

Electrical Tuning of Exciton Binding Energies in Monolayer WS_{2}

Phys Rev Lett. 2015 Sep 18;115(12):126802. doi: 10.1103/PhysRevLett.115.126802. Epub 2015 Sep 16.

Authors

Alexey Chernikov¹, Arend M van der Zande^{1

2

3}, Heather M Hill¹, Albert F Rigosi¹, Ajanth Velauthapillai^{1

4}, James Hone², Tony F Heinz^{1

5

6}

Affiliations

¹ Departments of Physics and Electrical Engineering, Columbia University, New York, New York 10027, USA.
² Department of Mechanical Engineering, Columbia University, New York, New York 10027, USA.
³ Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
⁴ Department of Physics and Materials Sciences Center, Philipps-Universität Marburg, Marburg 35032, Germany.
⁵ Department of Applied Physics, Stanford University, Stanford, California 94305, USA.
⁶ SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.

PMID: 26431003
DOI: 10.1103/PhysRevLett.115.126802

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}.