title: Tightly bound excitons in monolayer WSe(2).
abstract: 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 observed large exciton binding energy will also have a significant impact on next-generation photonics and optoelectronics applications based on 2D atomic crystals.
authors: Department of Physics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106, USA.
authors: Keliang
authors: K
authors: He
authors: Department of Physics and Astronomy, The University of Kansas, Lawrence, Kansas 66045, USA.
authors: Nardeep
authors: N
authors: Kumar
authors: Department of Physics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106, USA.
authors: Liang
authors: L
authors: Zhao
authors: Department of Physics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106, USA.
authors: Zefang
authors: Z
authors: Wang
authors: Kavli Institute at Cornell for Nanoscale Science and Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA.
authors: Kin Fai
authors: KF
authors: Mak
authors: Department of Physics and Astronomy, The University of Kansas, Lawrence, Kansas 66045, USA.
authors: Hui
authors: H
authors: Zhao
authors: Department of Physics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106, USA.
authors: Jie
authors: J
authors: Shan