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Investigations of Electron-Electron and Interlayer Electron-Phonon Coupling in van der Waals hBN/WSe(2)/hBN Heterostructures by Photoluminescence Excitation Experiments

Monolayers of transition metal dichalcogenides (TMDs) with their unique physical properties are very promising for future applications in novel electronic devices. In TMDs monolayers, strong and opposite spin splittings of the energy gaps at the K points allow for exciting carriers with various comb...

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Autores principales: Jadczak, Joanna, Kutrowska-Girzycka, Joanna, Schindler, Janina J., Debus, Joerg, Watanabe, Kenji, Taniguchi, Takashi, Ho, Ching-Hwa, Bryja, Leszek
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7830124/
https://www.ncbi.nlm.nih.gov/pubmed/33467435
http://dx.doi.org/10.3390/ma14020399
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author Jadczak, Joanna
Kutrowska-Girzycka, Joanna
Schindler, Janina J.
Debus, Joerg
Watanabe, Kenji
Taniguchi, Takashi
Ho, Ching-Hwa
Bryja, Leszek
author_facet Jadczak, Joanna
Kutrowska-Girzycka, Joanna
Schindler, Janina J.
Debus, Joerg
Watanabe, Kenji
Taniguchi, Takashi
Ho, Ching-Hwa
Bryja, Leszek
author_sort Jadczak, Joanna
collection PubMed
description Monolayers of transition metal dichalcogenides (TMDs) with their unique physical properties are very promising for future applications in novel electronic devices. In TMDs monolayers, strong and opposite spin splittings of the energy gaps at the K points allow for exciting carriers with various combinations of valley and spin indices using circularly polarized light, which can further be used in spintronics and valleytronics. The physical properties of van der Waals heterostructures composed of TMDs monolayers and hexagonal boron nitride (hBN) layers significantly depend on different kinds of interactions. Here, we report on observing both a strong increase in the emission intensity as well as a preservation of the helicity of the excitation light in the emission from hBN/WSe(2)/hBN heterostructures related to interlayer electron-phonon coupling. In combined low-temperature (T = 7 K) reflectivity contrast and photoluminescence excitation experiments, we find that the increase in the emission intensity is attributed to a double resonance, where the laser excitation and the combined Raman mode A′(1) (WSe(2)) + ZO (hBN) are in resonance with the excited (2s) and ground (1s) states of the A exciton in a WSe(2) monolayer. In reference to the 2s state, our interpretation is in contrast with previous reports, in which this state has been attributed to the hybrid exciton state existing only in the hBN-encapsulated WSe(2) monolayer. Moreover, we observe that the electron-phonon coupling also enhances the helicity preservation of the exciting light in the emission of all observed excitonic complexes. The highest helicity preservation of more than 60% is obtained in the emission of the neutral biexciton and negatively charged exciton (trion) in its triplet state. Additionally, to the best of our knowledge, the strongly intensified emission of the neutral biexciton XX(0) at double resonance condition is observed for the first time.
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spelling pubmed-78301242021-01-26 Investigations of Electron-Electron and Interlayer Electron-Phonon Coupling in van der Waals hBN/WSe(2)/hBN Heterostructures by Photoluminescence Excitation Experiments Jadczak, Joanna Kutrowska-Girzycka, Joanna Schindler, Janina J. Debus, Joerg Watanabe, Kenji Taniguchi, Takashi Ho, Ching-Hwa Bryja, Leszek Materials (Basel) Article Monolayers of transition metal dichalcogenides (TMDs) with their unique physical properties are very promising for future applications in novel electronic devices. In TMDs monolayers, strong and opposite spin splittings of the energy gaps at the K points allow for exciting carriers with various combinations of valley and spin indices using circularly polarized light, which can further be used in spintronics and valleytronics. The physical properties of van der Waals heterostructures composed of TMDs monolayers and hexagonal boron nitride (hBN) layers significantly depend on different kinds of interactions. Here, we report on observing both a strong increase in the emission intensity as well as a preservation of the helicity of the excitation light in the emission from hBN/WSe(2)/hBN heterostructures related to interlayer electron-phonon coupling. In combined low-temperature (T = 7 K) reflectivity contrast and photoluminescence excitation experiments, we find that the increase in the emission intensity is attributed to a double resonance, where the laser excitation and the combined Raman mode A′(1) (WSe(2)) + ZO (hBN) are in resonance with the excited (2s) and ground (1s) states of the A exciton in a WSe(2) monolayer. In reference to the 2s state, our interpretation is in contrast with previous reports, in which this state has been attributed to the hybrid exciton state existing only in the hBN-encapsulated WSe(2) monolayer. Moreover, we observe that the electron-phonon coupling also enhances the helicity preservation of the exciting light in the emission of all observed excitonic complexes. The highest helicity preservation of more than 60% is obtained in the emission of the neutral biexciton and negatively charged exciton (trion) in its triplet state. Additionally, to the best of our knowledge, the strongly intensified emission of the neutral biexciton XX(0) at double resonance condition is observed for the first time. MDPI 2021-01-15 /pmc/articles/PMC7830124/ /pubmed/33467435 http://dx.doi.org/10.3390/ma14020399 Text en © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Jadczak, Joanna
Kutrowska-Girzycka, Joanna
Schindler, Janina J.
Debus, Joerg
Watanabe, Kenji
Taniguchi, Takashi
Ho, Ching-Hwa
Bryja, Leszek
Investigations of Electron-Electron and Interlayer Electron-Phonon Coupling in van der Waals hBN/WSe(2)/hBN Heterostructures by Photoluminescence Excitation Experiments
title Investigations of Electron-Electron and Interlayer Electron-Phonon Coupling in van der Waals hBN/WSe(2)/hBN Heterostructures by Photoluminescence Excitation Experiments
title_full Investigations of Electron-Electron and Interlayer Electron-Phonon Coupling in van der Waals hBN/WSe(2)/hBN Heterostructures by Photoluminescence Excitation Experiments
title_fullStr Investigations of Electron-Electron and Interlayer Electron-Phonon Coupling in van der Waals hBN/WSe(2)/hBN Heterostructures by Photoluminescence Excitation Experiments
title_full_unstemmed Investigations of Electron-Electron and Interlayer Electron-Phonon Coupling in van der Waals hBN/WSe(2)/hBN Heterostructures by Photoluminescence Excitation Experiments
title_short Investigations of Electron-Electron and Interlayer Electron-Phonon Coupling in van der Waals hBN/WSe(2)/hBN Heterostructures by Photoluminescence Excitation Experiments
title_sort investigations of electron-electron and interlayer electron-phonon coupling in van der waals hbn/wse(2)/hbn heterostructures by photoluminescence excitation experiments
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7830124/
https://www.ncbi.nlm.nih.gov/pubmed/33467435
http://dx.doi.org/10.3390/ma14020399
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