1s-intraexcitonic dynamics in monolayer MoS2 probed by ultrafast mid-infrared spectroscopy

Soonyoung Cha; Ji Ho Sung; Sangwan Sim; Jun Park; Hoseok Heo; Moon Ho Jo; Hyunyong Choi

doi:10.1038/ncomms10768

1s-intraexcitonic dynamics in monolayer MoS₂ probed by ultrafast mid-infrared spectroscopy

Soonyoung Cha, Ji Ho Sung, Sangwan Sim, Jun Park, Hoseok Heo, Moon Ho Jo, Hyunyong Choi

Department of Electrical and Electronic Engineering

Research output: Contribution to journal › Article › peer-review

67 Citations (Scopus)

Abstract

The 1s exciton - the ground state of a bound electron-hole pair - is central to understanding the photoresponse of monolayer transition metal dichalcogenides. Above the 1s exciton, recent visible and near-infrared investigations have revealed that the excited excitons are much richer, exhibiting a series of Rydberg-like states. A natural question is then how the internal excitonic transitions are interrelated on photoexcitation. Accessing these intraexcitonic transitions, however, demands a fundamentally different experimental tool capable of probing optical transitions from 1s 'bright' to np 'dark' states. Here we employ ultrafast mid-infrared spectroscopy to explore the 1s intraexcitonic transitions in monolayer MoS₂. We observed twofold 1s→3p intraexcitonic transitions within the A and B excitons and 1s→2p transition between the A and B excitons. Our results revealed that it takes about 0.7 ps for the 1s A exciton to reach quasi-equilibrium; a characteristic time that is associated with a rapid population transfer from the 1s B exciton, providing rich characteristics of many-body exciton dynamics in two-dimensional materials.

Original language	English
Article number	10768
Journal	Nature communications
Volume	7
DOIs	https://doi.org/10.1038/ncomms10768
Publication status	Published - 2016 Feb 25

Bibliographical note

Funding Information:
S. Cha, S. Sim, J. Park and H. Choi were supported by the National Research Foundation of Korea (NRF) through the government of Korea (MSIP) (Grants No. NRF-2011-0013255, NRF-2009-0083512, NRF-2015R1A2A1A10052520), Global Frontier Program (2014M3A6B3063709), the Yonsei University Yonsei-SNU Collaborative Research Fund of 2014 and the Yonsei University Future-leading Research Initiative of 2014. J.H.S., H.H. and M.-H.J. were supported by Institute for Basic Science (IBS), Korea under the contract number of IBS-R014-G1-2016-a00.

All Science Journal Classification (ASJC) codes

Chemistry(all)
Biochemistry, Genetics and Molecular Biology(all)
Physics and Astronomy(all)

Access to Document

10.1038/ncomms10768

Cite this

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title = "1s-intraexcitonic dynamics in monolayer MoS2 probed by ultrafast mid-infrared spectroscopy",

abstract = "The 1s exciton - the ground state of a bound electron-hole pair - is central to understanding the photoresponse of monolayer transition metal dichalcogenides. Above the 1s exciton, recent visible and near-infrared investigations have revealed that the excited excitons are much richer, exhibiting a series of Rydberg-like states. A natural question is then how the internal excitonic transitions are interrelated on photoexcitation. Accessing these intraexcitonic transitions, however, demands a fundamentally different experimental tool capable of probing optical transitions from 1s 'bright' to np 'dark' states. Here we employ ultrafast mid-infrared spectroscopy to explore the 1s intraexcitonic transitions in monolayer MoS2. We observed twofold 1s→3p intraexcitonic transitions within the A and B excitons and 1s→2p transition between the A and B excitons. Our results revealed that it takes about 0.7 ps for the 1s A exciton to reach quasi-equilibrium; a characteristic time that is associated with a rapid population transfer from the 1s B exciton, providing rich characteristics of many-body exciton dynamics in two-dimensional materials.",

author = "Soonyoung Cha and Sung, {Ji Ho} and Sangwan Sim and Jun Park and Hoseok Heo and Jo, {Moon Ho} and Hyunyong Choi",

note = "Funding Information: S. Cha, S. Sim, J. Park and H. Choi were supported by the National Research Foundation of Korea (NRF) through the government of Korea (MSIP) (Grants No. NRF-2011-0013255, NRF-2009-0083512, NRF-2015R1A2A1A10052520), Global Frontier Program (2014M3A6B3063709), the Yonsei University Yonsei-SNU Collaborative Research Fund of 2014 and the Yonsei University Future-leading Research Initiative of 2014. J.H.S., H.H. and M.-H.J. were supported by Institute for Basic Science (IBS), Korea under the contract number of IBS-R014-G1-2016-a00.",

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AU - Cha, Soonyoung

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AU - Sim, Sangwan

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AU - Heo, Hoseok

AU - Jo, Moon Ho

AU - Choi, Hyunyong

N1 - Funding Information: S. Cha, S. Sim, J. Park and H. Choi were supported by the National Research Foundation of Korea (NRF) through the government of Korea (MSIP) (Grants No. NRF-2011-0013255, NRF-2009-0083512, NRF-2015R1A2A1A10052520), Global Frontier Program (2014M3A6B3063709), the Yonsei University Yonsei-SNU Collaborative Research Fund of 2014 and the Yonsei University Future-leading Research Initiative of 2014. J.H.S., H.H. and M.-H.J. were supported by Institute for Basic Science (IBS), Korea under the contract number of IBS-R014-G1-2016-a00.

PY - 2016/2/25

Y1 - 2016/2/25

N2 - The 1s exciton - the ground state of a bound electron-hole pair - is central to understanding the photoresponse of monolayer transition metal dichalcogenides. Above the 1s exciton, recent visible and near-infrared investigations have revealed that the excited excitons are much richer, exhibiting a series of Rydberg-like states. A natural question is then how the internal excitonic transitions are interrelated on photoexcitation. Accessing these intraexcitonic transitions, however, demands a fundamentally different experimental tool capable of probing optical transitions from 1s 'bright' to np 'dark' states. Here we employ ultrafast mid-infrared spectroscopy to explore the 1s intraexcitonic transitions in monolayer MoS2. We observed twofold 1s→3p intraexcitonic transitions within the A and B excitons and 1s→2p transition between the A and B excitons. Our results revealed that it takes about 0.7 ps for the 1s A exciton to reach quasi-equilibrium; a characteristic time that is associated with a rapid population transfer from the 1s B exciton, providing rich characteristics of many-body exciton dynamics in two-dimensional materials.

AB - The 1s exciton - the ground state of a bound electron-hole pair - is central to understanding the photoresponse of monolayer transition metal dichalcogenides. Above the 1s exciton, recent visible and near-infrared investigations have revealed that the excited excitons are much richer, exhibiting a series of Rydberg-like states. A natural question is then how the internal excitonic transitions are interrelated on photoexcitation. Accessing these intraexcitonic transitions, however, demands a fundamentally different experimental tool capable of probing optical transitions from 1s 'bright' to np 'dark' states. Here we employ ultrafast mid-infrared spectroscopy to explore the 1s intraexcitonic transitions in monolayer MoS2. We observed twofold 1s→3p intraexcitonic transitions within the A and B excitons and 1s→2p transition between the A and B excitons. Our results revealed that it takes about 0.7 ps for the 1s A exciton to reach quasi-equilibrium; a characteristic time that is associated with a rapid population transfer from the 1s B exciton, providing rich characteristics of many-body exciton dynamics in two-dimensional materials.

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