He K, Kumar N, Zhao L, Wang Z, Mak KF, Zhao H, Shan J. Tightly bound excitons in monolayer WSe(2).
PHYSICAL REVIEW LETTERS 2014;
113:026803. [PMID:
25062219 DOI:
10.1103/physrevlett.113.026803]
[Citation(s) in RCA: 386] [Impact Index Per Article: 38.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Indexed: 05/23/2023]
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.
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