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Understanding the remarkable excitonic effects and controlling the exciton binding energies in two-dimensional (2D) semiconductors is crucial in unlocking their full potential for use in future photonic and optoelectronic devices. Here, we demonstrate large excitonic effects and gate-tunable exciton binding energies in single-layer rhenium diselenide (ReSe2) on a back-gated graphene device. We used scanning tunneling spectroscopy (STS) and photoluminescence (PL) spectroscopy to measure the quasiparticle electronic and optical band gap of single-layer ReSe2 respectively, yielding a large exciton binding energy of 500 meV. Further, we achieved continuous tuning of the electronic band gap and exciton binding energy of monolayer ReSe2 by hundreds of meV through electrostatic gating, attributed to tunable Coulomb interactions arising from the gate-controlled free carriers in graphene. Our findings open a new avenue for controlling the bandgap renormalization and exciton binding energies in 2D semiconductors for a wide range of technological applications.

Rights:

• Creative Commons BY-NC Attribution-NonCommercial 4.0 International
  

Keyword: Excitonic effects, ReSe2, gate-tunable

Date published: 2019-07-05

Publisher: American Association for the Advancement of Science (AAAS)

Journal:

• Science Advances (ISSN: 23752548) vol. 5 issue. 7

Funding:

• Air Force Office of Scientific Research FA9550-17-1-0304
• National University of Singapore Young Investigator Award R-607-000-094-133
• MOE tier2 grants R-143-000682-112
• MOE Tier 2 grants R-143-000-A06-112
• NRF Medium Sized Centre Programme R-723-000-001-281
• the Singapore Ministry of Education AcRF Tier2 MOE2017-T2-2-140

Manuscript type: Publisher's version (Version of record)

MDR DOI:

First published URL: https://doi.org/10.1126/sciadv.aaw2347

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Updated at: 2025-02-23 22:51:03 +0900

Published on MDR: 2025-02-23 22:51:03 +0900