In atomically thin semiconductors, localized exciton (XL) coupled to light provides a new class of optical sources for potential applications in quantum communication. However, in most studies, XL photoluminescence (PL) from crystal defects has mainly been observed in cryogenic conditions because of their sub-wavelength emission region and low quantum yield at room temperature. Hybrid-modality of cavity-spectroscopy to induce and probe the XL emissions at the nanoscale in atomically thin semiconductors is presented. By placing a WSe2 monolayer on the two extremely sharp Au tips in a bowtie antenna with a radius of curvature of <1 nm, tensile strain of ≈0.3% is effectively induced in a <30 nm region to create robust XL states. The Au tip then approaches the strained crystal region to enhance the XL emissions and probe them with tip-enhanced photoluminescence (TEPL) spectroscopy at room temperature. Through this triple-sharp-tips cavity-spectroscopy with <15 nm spatial resolution, TEPL enhancement as high as ≈4.0 × 104 by the Purcell effect is achieved, and peak energy shifts of XL up to ≈40 meV are observed. This approach combining nano-cavity and -spectroscopy provides a systematic way to induce and probe the radiative emission of localized excitons in 2D semiconductors offering new strategies for dynamic quantum nano-optical devices.
Bibliographical noteFunding Information:
H.L. and I.K. contributed equally to this work. This work was supported by the National Research Foundation of Korea (NRF) grants (2019K2A9A1A06099937 and 2020R1C1C1011301). J.R. acknowledges the NRF grants (2019R1A2C3003129, 2019M3A6B3030637, 2019R1A5A8080290) funded by the Ministry of Science and ICT (MSIT). I.K. acknowledges the NRF Sejong Science fellowship (NRF‐2021R1C1C2004291) funded by the MSIT of the Korean government. Y.K. acknowledges a fellowship from Hyundai Motor Chung Mong‐Koo Foundation and the POSTECHIAN fellowship from POSTECH. M.S.J. thanks the Creative Materials Discovery Program through NRF funded by the MSIT (2019M3D1A1078304). H.‐G.P. acknowledges the NRF grants (2021R1A2C3006781 and 2020R1A4A2002828) funded by the MSIT. M.B.R. acknowledges support from the National Science Foundation (NSF Grant CHE‐1709822). The authors thank D.S.L. and J.H.C. for the assistance of figure illustration.
© 2021 Wiley-VCH GmbH
- localized exciton
- plasmonic structures
- purcell effect
- tip-enhanced photoluminescence
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Materials Science(all)