Tightly bound excitons in monolayer WSe2

Keliang He, Nardeep Kumar, Liang Zhao, Zefang Wang, Kin Fai Mak, Hui Zhao, Jie Shan

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Exciton binding energy and excited states in monolayers of tungsten diselenide (WSe2) 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.

Original languageEnglish (US)
Article number026803
JournalPhysical Review Letters
Issue number2
StatePublished - Jul 10 2014

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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    He, K., Kumar, N., Zhao, L., Wang, Z., Mak, K. F., Zhao, H., & Shan, J. (2014). Tightly bound excitons in monolayer WSe2. Physical Review Letters, 113(2), [026803]. https://doi.org/10.1103/PhysRevLett.113.026803