Interactions and ultrafast dynamics of exciton complexes in a monolayer semiconductor with electron gas
We present femtosecond pump-probe measurements of neutral and charged exciton optical response in monolayer MoSe2 to resonant photoexcitation of a given exciton state in the presence of 2D electron gas. We show that creation of charged exciton (X−) population in a given K+, K− valley requires the ca...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
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De Gruyter
2024-02-01
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| Series: | Nanophotonics |
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| Online Access: | https://doi.org/10.1515/nanoph-2023-0913 |
| _version_ | 1797258389912289280 |
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| author | Rodek Aleksander Oreszczuk Kacper Kazimierczuk Tomasz Howarth James Taniguchi Takashi Watanabe Kenji Potemski Marek Kossacki Piotr |
| author_facet | Rodek Aleksander Oreszczuk Kacper Kazimierczuk Tomasz Howarth James Taniguchi Takashi Watanabe Kenji Potemski Marek Kossacki Piotr |
| author_sort | Rodek Aleksander |
| collection | DOAJ |
| description | We present femtosecond pump-probe measurements of neutral and charged exciton optical response in monolayer MoSe2 to resonant photoexcitation of a given exciton state in the presence of 2D electron gas. We show that creation of charged exciton (X−) population in a given K+, K− valley requires the capture of available free carriers in the opposite valley and reduces the interaction of neutral exciton (X) with the electron Fermi sea. We also observe spectral broadening of the X transition line with the increasing X− population caused by efficient scattering and excitation induced dephasing. From the valley-resolved analysis of the observed effects we are able to extract the spin-valley relaxation times of free carriers as a function of carrier density. Moreover, we analyze the oscillator strength and energy shift of X in the regime of interaction with electron Fermi sea under resonant excitation. From this we can observe the process of X decay by radiative recombination paired with trion formation. We demonstrate an increase of neutral exciton relaxation rate with the introduction of Fermi sea of electrons. We ascribe the observed effect to the increased efficiency of the trion formation, as well as the radiative decay caused by the screening of disorder by the free carriers. |
| first_indexed | 2024-03-07T21:33:49Z |
| format | Article |
| id | doaj.art-967ba7ebfcaa4033a49e171016929cbb |
| institution | Directory Open Access Journal |
| issn | 2192-8614 |
| language | English |
| last_indexed | 2024-04-24T22:52:46Z |
| publishDate | 2024-02-01 |
| publisher | De Gruyter |
| record_format | Article |
| series | Nanophotonics |
| spelling | doaj.art-967ba7ebfcaa4033a49e171016929cbb2024-03-18T10:28:06ZengDe GruyterNanophotonics2192-86142024-02-0113448749710.1515/nanoph-2023-0913Interactions and ultrafast dynamics of exciton complexes in a monolayer semiconductor with electron gasRodek Aleksander0Oreszczuk Kacper1Kazimierczuk Tomasz2Howarth James3Taniguchi Takashi4Watanabe Kenji5Potemski Marek6Kossacki Piotr7Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093Warszawa, PolandFaculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093Warszawa, PolandFaculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093Warszawa, PolandNational Graphene Institute, University of Manchester, M13 9PL, Manchester, UKInternational Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba305-0044, JapanResearch Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba305-0044, JapanFaculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093Warszawa, PolandFaculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093Warszawa, PolandWe present femtosecond pump-probe measurements of neutral and charged exciton optical response in monolayer MoSe2 to resonant photoexcitation of a given exciton state in the presence of 2D electron gas. We show that creation of charged exciton (X−) population in a given K+, K− valley requires the capture of available free carriers in the opposite valley and reduces the interaction of neutral exciton (X) with the electron Fermi sea. We also observe spectral broadening of the X transition line with the increasing X− population caused by efficient scattering and excitation induced dephasing. From the valley-resolved analysis of the observed effects we are able to extract the spin-valley relaxation times of free carriers as a function of carrier density. Moreover, we analyze the oscillator strength and energy shift of X in the regime of interaction with electron Fermi sea under resonant excitation. From this we can observe the process of X decay by radiative recombination paired with trion formation. We demonstrate an increase of neutral exciton relaxation rate with the introduction of Fermi sea of electrons. We ascribe the observed effect to the increased efficiency of the trion formation, as well as the radiative decay caused by the screening of disorder by the free carriers.https://doi.org/10.1515/nanoph-2023-0913nonlinear spectroscopytransition metal dichalcogenide monolayerfermi seaexcitontrionultrafast dynamics |
| spellingShingle | Rodek Aleksander Oreszczuk Kacper Kazimierczuk Tomasz Howarth James Taniguchi Takashi Watanabe Kenji Potemski Marek Kossacki Piotr Interactions and ultrafast dynamics of exciton complexes in a monolayer semiconductor with electron gas Nanophotonics nonlinear spectroscopy transition metal dichalcogenide monolayer fermi sea exciton trion ultrafast dynamics |
| title | Interactions and ultrafast dynamics of exciton complexes in a monolayer semiconductor with electron gas |
| title_full | Interactions and ultrafast dynamics of exciton complexes in a monolayer semiconductor with electron gas |
| title_fullStr | Interactions and ultrafast dynamics of exciton complexes in a monolayer semiconductor with electron gas |
| title_full_unstemmed | Interactions and ultrafast dynamics of exciton complexes in a monolayer semiconductor with electron gas |
| title_short | Interactions and ultrafast dynamics of exciton complexes in a monolayer semiconductor with electron gas |
| title_sort | interactions and ultrafast dynamics of exciton complexes in a monolayer semiconductor with electron gas |
| topic | nonlinear spectroscopy transition metal dichalcogenide monolayer fermi sea exciton trion ultrafast dynamics |
| url | https://doi.org/10.1515/nanoph-2023-0913 |
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