Tightly Bound Excitons in Monolayer WSe 2

Exciton binding energy and excited states in monolayers of tungsten diselenide (WSe(2)) are investigated using the combined linear absorption and two-photon photoluminescence excitation spectroscopy. The exciton binding energy is determined to be 0.37 eV, which is about an order of magnitude larger than that in III-V semiconductor quantum wells and renders the exciton excited states observable even at room temperature. The exciton excitation spectrum with both experimentally determined one- and two-photon active states is distinct from the simple two-dimensional (2D) hydrogenic model. This result reveals significantly reduced and nonlocal dielectric screening of Coulomb interactions in 2D semiconductors. The…

• NS
  National Science Foundation

  Awards: DMR-0954486, 0907477, 0954486, 0349201, DMR-0349201
• CW
  Case Western Reserve University
• DO
  Division of Materials Research

  Awards: DMR-0954486, 0954486