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Drift-dominant exciton funneling and trion conversion in 2D semiconductors on the nanogap

Lee, Hyeongwoo and Koo, Yeonjeong and Choi, Jinseong and Kumar, Shailabh and Lee, Hyoung-Taek and Ji, Gangseon and Choi, Soo Ho and Kang, Mingu and Kim, Ki Kang and Park, Hyeong-Ryeol and Choo, Hyuck and Park, Kyoung-Duck (2022) Drift-dominant exciton funneling and trion conversion in 2D semiconductors on the nanogap. Science Advances, 8 (5). Art. No. eabm5236. ISSN 2375-2548. PMCID PMC8816338. doi:10.1126/sciadv.abm5236.

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Understanding and controlling the nanoscale transport of excitonic quasiparticles in atomically thin two-dimensional (2D) semiconductors are crucial to produce highly efficient nano-excitonic devices. Here, we present a nanogap device to selectively confine excitons or trions of 2D transition metal dichalcogenides at the nanoscale, facilitated by the drift-dominant exciton funneling into the strain-induced local spot. We investigate the spatiospectral characteristics of the funneled excitons in a WSe₂ monolayer (ML) and converted trions in a MoS₂ ML using hyperspectral tip-enhanced photoluminescence imaging with <15-nm spatial resolution. In addition, we dynamically control the exciton funneling and trion conversion rate by the gigapascal-scale tip pressure engineering. Through a drift-diffusion model, we confirm an exciton funneling efficiency of ∼25% with a significantly low strain threshold (∼0.1%), which sufficiently exceeds the efficiency of ∼3% in previous studies. This work provides a previously unexplored strategy to facilitate efficient exciton transport and trion conversion of 2D semiconductor devices.

Item Type:Article
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URLURL TypeDescription Information CentralArticle
Lee, Hyeongwoo0000-0002-1602-2787
Koo, Yeonjeong0000-0003-3648-1275
Kumar, Shailabh0000-0001-5383-3282
Lee, Hyoung-Taek0000-0002-7180-7114
Choi, Soo Ho0000-0002-9927-0101
Kang, Mingu0000-0001-5425-2009
Park, Hyeong-Ryeol0000-0002-6586-9466
Choo, Hyuck0000-0002-8903-7939
Park, Kyoung-Duck0000-0002-9302-9384
Additional Information:© 2022 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC). Received: 23 September 2021. Accepted: 14 December 2021. This work was supported by the 2018 Research Fund (1.180091.01) of UNIST (Ulsan National Institute of Science and Technology) and the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (2019K2A9A1A06099937 and NRF-2020R1C1C1011301). H.-R.P. acknowledges NRF-2021R1A2C1008452. S.H.C. and K.K.K. acknowledge the support by the Institute for Basic Science (IBS-R011-D1). K.K.K. acknowledges the Basic Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT, and Future Planning (2018R1A2B2002302). Author contributions: H.L., Y.K., and K.-D.P. conceived the experiments. H.L. and Y.K. performed the TEPL spectroscopy and control experiments. S.K., H.-T.L., G.J., H.-R.P., and H.C. designed and fabricated the nanogap. S.H.C. and K.K.K. prepared and transferred TMD MLs on the Au nanogap device. J.C. performed theoretical calculation and modeling of exciton distribution. H.L., Y.K., J.C., M.K., and K.-D.P. analyzed the data, and all authors discussed the results. H.L., Y.K., and K.-D.P. wrote the manuscript with contributions from all authors. K.-D.P. supervised the project. The authors declare that they have no competing interests. Data and materials availability: All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials.
Funding AgencyGrant Number
Ulsan National Institute of Science and Technology1.180091.01
National Research Foundation of Korea2019K2A9A1A06099937
National Research Foundation of Korea2020R1C1C1011301
National Research Foundation of Korea2021R1A2C1008452
Ministry of Science, ICT and Future Planning (Korea)IBS-R011-D1
Ministry of Science, ICT and Future Planning (Korea)2018R1A2B2002302
Issue or Number:5
PubMed Central ID:PMC8816338
Record Number:CaltechAUTHORS:20220207-700367000
Persistent URL:
Official Citation:Drift-dominant exciton funneling and trion conversion in 2D semiconductors on the nanogap. Hyeongwoo Lee, Yeonjeong Koo, Jinseong Choi, Shailabh Kumar, Hyoung-Taek Lee, Gangseon Ji, Soo Ho Choi, Mingu Kang, Ki Kang Kim, Hyeong-Ryeol Park, Hyuck Choo, Kyoung-Duck Park. Sci. Adv., 8 (5), eabm5236; DOI: 10.1126/sciadv.abm5236
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:113306
Deposited By: George Porter
Deposited On:07 Feb 2022 20:28
Last Modified:22 Feb 2022 19:14

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