1
|
Liu Q, Wei K, Tang Y, Ye Y, Li S, Yu H, Pan Z, Jiang T. Charged Biexciton Formation with Many-Body-Induced Valley Polarization in a Monolayer Semiconductor. ACS NANO 2025; 19:13356-13365. [PMID: 40150817 DOI: 10.1021/acsnano.5c01195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/29/2025]
Abstract
In the realm of many-body physics, the study of low-dimensional excitonic complexes has emerged as a compelling area of research, offering tunable modifications and highlighting quasiparticle interactions as key drivers for advancing valleytronics. Building upon extensive studies of simpler few-body systems such as excitons and trions, here we present a comprehensive exploration of the valley dynamics in more complex five-body charged biexciton (XX-) in monolayer WS2 using helicity-resolved ultrafast spectroscopy. We observe a near-unity degree of valley polarization at a moderate temperature of ∼150 K, which persists substantially longer than the population lifetime. Intriguingly, this polarization reveals an unexpected positive correlation with external disturbances such as temperature and pump fluence─behaviors distinct from conventional few-body systems. These phenomena are attributed to the inherent suppression of valley-exchange interactions in XX-, combined with its dual formation mechanisms: direct optical excitation and indirect conversion mediated by trion-trion interactions. Our results demonstrate that multibody excitonic complexes are stable candidates for maintaining valley polarization and could enable valleytronic applications that utilize many-body correlations.
Collapse
Affiliation(s)
- Qirui Liu
- College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China
| | - Ke Wei
- Institute for Quantum Science and Technology, College of Science, National University of Defense Technology, Changsha 410073, China
- Hunan Research Center of the Basic Discipline for Physical States, Changsha 410073, China
| | - Yuxiang Tang
- Institute for Quantum Science and Technology, College of Science, National University of Defense Technology, Changsha 410073, China
| | - Yingqian Ye
- College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China
| | - Siwei Li
- College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China
| | - Hongyun Yu
- College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China
| | - Zhichao Pan
- Institute for Quantum Science and Technology, College of Science, National University of Defense Technology, Changsha 410073, China
| | - Tian Jiang
- Institute for Quantum Science and Technology, College of Science, National University of Defense Technology, Changsha 410073, China
- Hunan Research Center of the Basic Discipline for Physical States, Changsha 410073, China
| |
Collapse
|
2
|
Shao YP, Li YQ, Zheng JD, Tan YF, Guan Z, Zhong N, Yue FY, Tong WY, Duan CG. Valley manipulation by external fields in two-dimensional materials and their hybrid systems. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 37:053003. [PMID: 39504648 DOI: 10.1088/1361-648x/ad8f81] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2024] [Accepted: 11/06/2024] [Indexed: 11/08/2024]
Abstract
Investigating two-dimensional (2D) valleytronic materials opens a new chapter in physics and facilitates the emergence of pioneering technologies. Nevertheless, this nascent field faces substantial challenges, primarily attributed to the inherent issue of valley energy degeneracy and the manipulation of valley properties. To break these constraints, the application of external fields has become pivotal for both generating and manipulating the valley properties of 2D systems. This paper takes a close look at the latest progress in modulating the valley properties of 2D valleytronic materials using external fields, covering a wide array of configurations from monolayers and bilayers to intricate heterostructures. We hope that this overview will inspire more exciting discoveries and significantly propel the evolution of valleytronics within the realm of 2D material research.
Collapse
Affiliation(s)
- Ya-Ping Shao
- Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai 200241, People's Republic of China
| | - Yun-Qin Li
- Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai 200241, People's Republic of China
| | - Jun-Ding Zheng
- Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai 200241, People's Republic of China
| | - Yi-Fan Tan
- Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai 200241, People's Republic of China
| | - Zhao Guan
- Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai 200241, People's Republic of China
| | - Ni Zhong
- Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai 200241, People's Republic of China
| | - Fang-Yu Yue
- Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai 200241, People's Republic of China
| | - Wen-Yi Tong
- Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai 200241, People's Republic of China
| | - Chun-Gang Duan
- Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai 200241, People's Republic of China
- Collavorative Innovation center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, People's Republic of China
- Shanghai Center of Brain-inspired Intelligent Materials and Devices, East China Normal University, Shanghai 200241, People's Republic of China
| |
Collapse
|
3
|
Adler ER, Le TDM, Boulares I, Boyd R, He Y, Rhodes D, Van Keuren E, Barbara P, Najmaei S. Observation of Multi-Phonon Emission in Monolayer WS 2 on Various Substrates. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 14:37. [PMID: 38202492 PMCID: PMC10780943 DOI: 10.3390/nano14010037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 12/14/2023] [Accepted: 12/19/2023] [Indexed: 01/12/2024]
Abstract
Transition metal dichalcogenides (TMDs) have unique absorption and emission properties that stem from their large excitonic binding energies, reduced-dielectric screening, and strong spin-orbit coupling. However, the role of substrates, phonons, and material defects in the excitonic scattering processes remains elusive. In tungsten-based TMDs, it is known that the excitons formed from electrons in the lower-energy conduction bands are dark in nature, whereas low-energy emissions in the photoluminescence spectrum have been linked to the brightening of these transitions, either via defect scattering or via phonon scattering with first-order phonon replicas. Through temperature and incident-power-dependent studies of WS2 grown by CVD or exfoliated from high-purity bulk crystal on different substrates, we demonstrate that the strong exciton-phonon coupling yields brightening of dark transitions up to sixth-order phonon replicas. We discuss the critical role of defects in the brightening pathways of dark excitons and their phonon replicas, and we elucidate that these emissions are intrinsic to the material and independent of substrate, encapsulation, growth method, and transfer approach.
Collapse
Affiliation(s)
- Eli R. Adler
- Department of Physics, Georgetown University, Washington, DC 20057, USA; (E.R.A.); (T.D.M.L.); (E.V.K.)
- U.S. Army Combat Capabilities Development Command, Army Research Laboratory, Adelphi, MD 20783, USA
| | - Thy Doan Mai Le
- Department of Physics, Georgetown University, Washington, DC 20057, USA; (E.R.A.); (T.D.M.L.); (E.V.K.)
| | - Ibrahim Boulares
- U.S. Army Combat Capabilities Development Command, Army Research Laboratory, Adelphi, MD 20783, USA
| | - Robert Boyd
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Yangchen He
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Daniel Rhodes
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Edward Van Keuren
- Department of Physics, Georgetown University, Washington, DC 20057, USA; (E.R.A.); (T.D.M.L.); (E.V.K.)
| | - Paola Barbara
- Department of Physics, Georgetown University, Washington, DC 20057, USA; (E.R.A.); (T.D.M.L.); (E.V.K.)
| | - Sina Najmaei
- U.S. Army Combat Capabilities Development Command, Army Research Laboratory, Adelphi, MD 20783, USA
| |
Collapse
|
4
|
Feuer MG, Montblanch ARP, Sayyad MY, Purser CM, Qin Y, Alexeev EM, Cadore AR, Rosa BLT, Kerfoot J, Mostaani E, Kalȩba R, Kolari P, Kopaczek J, Watanabe K, Taniguchi T, Ferrari AC, Kara DM, Tongay S, Atatüre M. Identification of Exciton Complexes in Charge-Tunable Janus W SeS Monolayers. ACS NANO 2023; 17:7326-7334. [PMID: 37058341 PMCID: PMC10134503 DOI: 10.1021/acsnano.2c10697] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 03/29/2023] [Indexed: 06/17/2023]
Abstract
Janus transition-metal dichalcogenide monolayers are artificial materials, where one plane of chalcogen atoms is replaced by chalcogen atoms of a different type. Theory predicts an in-built out-of-plane electric field, giving rise to long-lived, dipolar excitons, while preserving direct-bandgap optical transitions in a uniform potential landscape. Previous Janus studies had broad photoluminescence (>18 meV) spectra obfuscating their specific excitonic origin. Here, we identify the neutral and the negatively charged inter- and intravalley exciton transitions in Janus WSeS monolayers with ∼6 meV optical line widths. We integrate Janus monolayers into vertical heterostructures, allowing doping control. Magneto-optic measurements indicate that monolayer WSeS has a direct bandgap at the K points. Our results pave the way for applications such as nanoscale sensing, which relies on resolving excitonic energy shifts, and the development of Janus-based optoelectronic devices, which requires charge-state control and integration into vertical heterostructures.
Collapse
Affiliation(s)
- Matthew
S. G. Feuer
- Cavendish
Laboratory, University of Cambridge, 19 J. J. Thomson Avenue, Cambridge, CB3 0HE, U.K.
| | | | - Mohammed Y. Sayyad
- Materials
Science and Engineering, School for Engineering of Matter, Transport
and Energy, Arizona State University, Tempe, Arizona 85287, United States
| | - Carola M. Purser
- Cavendish
Laboratory, University of Cambridge, 19 J. J. Thomson Avenue, Cambridge, CB3 0HE, U.K.
- Cambridge
Graphene Centre, University of Cambridge, 9 J. J. Thomson Avenue, Cambridge, CB3 0FA, U.K.
| | - Ying Qin
- Materials
Science and Engineering, School for Engineering of Matter, Transport
and Energy, Arizona State University, Tempe, Arizona 85287, United States
| | - Evgeny M. Alexeev
- Cavendish
Laboratory, University of Cambridge, 19 J. J. Thomson Avenue, Cambridge, CB3 0HE, U.K.
- Cambridge
Graphene Centre, University of Cambridge, 9 J. J. Thomson Avenue, Cambridge, CB3 0FA, U.K.
| | - Alisson R. Cadore
- Cambridge
Graphene Centre, University of Cambridge, 9 J. J. Thomson Avenue, Cambridge, CB3 0FA, U.K.
| | - Barbara L. T. Rosa
- Cambridge
Graphene Centre, University of Cambridge, 9 J. J. Thomson Avenue, Cambridge, CB3 0FA, U.K.
| | - James Kerfoot
- Cambridge
Graphene Centre, University of Cambridge, 9 J. J. Thomson Avenue, Cambridge, CB3 0FA, U.K.
| | - Elaheh Mostaani
- Cambridge
Graphene Centre, University of Cambridge, 9 J. J. Thomson Avenue, Cambridge, CB3 0FA, U.K.
| | - Radosław Kalȩba
- Cavendish
Laboratory, University of Cambridge, 19 J. J. Thomson Avenue, Cambridge, CB3 0HE, U.K.
| | - Pranvera Kolari
- Materials
Science and Engineering, School for Engineering of Matter, Transport
and Energy, Arizona State University, Tempe, Arizona 85287, United States
| | - Jan Kopaczek
- Materials
Science and Engineering, School for Engineering of Matter, Transport
and Energy, Arizona State University, Tempe, Arizona 85287, United States
| | - Kenji Watanabe
- Research
Center for Functional Materials, National
Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- International
Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Andrea C. Ferrari
- Cambridge
Graphene Centre, University of Cambridge, 9 J. J. Thomson Avenue, Cambridge, CB3 0FA, U.K.
| | - Dhiren M. Kara
- Cavendish
Laboratory, University of Cambridge, 19 J. J. Thomson Avenue, Cambridge, CB3 0HE, U.K.
| | - Sefaattin Tongay
- Materials
Science and Engineering, School for Engineering of Matter, Transport
and Energy, Arizona State University, Tempe, Arizona 85287, United States
| | - Mete Atatüre
- Cavendish
Laboratory, University of Cambridge, 19 J. J. Thomson Avenue, Cambridge, CB3 0HE, U.K.
| |
Collapse
|
5
|
Abstract
Interactions between quasiparticles are of fundamental importance and ultimately determine the macroscopic properties of quantum matter. A famous example is the phenomenon of superconductivity, which arises from attractive electron-electron interactions that are mediated by phonons or even other more exotic fluctuations in the material. Here we introduce mobile exciton impurities into a two-dimensional electron gas and investigate the interactions between the resulting Fermi polaron quasiparticles. We employ multi-dimensional coherent spectroscopy on monolayer WS2, which provides an ideal platform for determining the nature of polaron-polaron interactions due to the underlying trion fine structure and the valley specific optical selection rules. At low electron doping densities, we find that the dominant interactions are between polaron states that are dressed by the same Fermi sea. In the absence of bound polaron pairs (bipolarons), we show using a minimal microscopic model that these interactions originate from a phase-space filling effect, where excitons compete for the same electrons. We furthermore reveal the existence of a bipolaron bound state with remarkably large binding energy, involving excitons in different valleys cooperatively bound to the same electron. Our work lays the foundation for probing and understanding strong electron correlation effects in two-dimensional layered structures such as moiré superlattices. Here, the authors investigate the interactions between Fermi polarons in monolayer WS2 by multi-dimensional coherent spectroscopy, and find that, at low electron doping densities, the dominant interactions are between polaron states that are dressed by the same Fermi sea. They also observe a bipolaron bound state with large binding energy, involving excitons in different valleys cooperatively bound to the same electron.
Collapse
|
6
|
Żuberek E, Majak M, Lubczyński J, Debus J, Watanabe K, Taniguchi T, Ho CH, Bryja L, Jadczak J. Upconversion photoluminescence excitation reveals exciton-trion and exciton-biexciton coupling in hBN/WS[Formula: see text]/hBN van der Waals heterostructures. Sci Rep 2022; 12:13699. [PMID: 35953508 PMCID: PMC9372078 DOI: 10.1038/s41598-022-18104-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 08/05/2022] [Indexed: 11/10/2022] Open
Abstract
Monolayers of transition-metal dichalcogenides with direct band gap located at the binary [Formula: see text] points of the Brillouin zone are promising materials for applications in opto- and spin-electronics due to strongly enhanced Coulomb interactions and specific spin-valley properties. They furthermore represent a unique platform to study electron-electron and electron-phonon interactions in diverse exciton complexes. Here, we demonstrate processes in which the neutral biexciton and two negative trions, namely the spin-triplet and spin-singlet trions, upconvert light into a bright intravalley exciton in an hBN-encapsulated WS[Formula: see text] monolayer. We propose that the energy gains required in the polarized upconversion photoluminescence originate from different interactions including resonant optical phonons, a cooling of resident electrons and a non-local and an anisotropic electron-hole exchange, respectively. The temperature dependence (7-120 K) of the excitonic upconversion intensity obtained at excitation energies corresponding to the biexciton and trions provides insight into an increasing phonon population as well as a thermally enhanced electron scattering. Our study sheds new light on the understanding of excitonic spin and valley properties of van der Waals heterostructures and improves the understanding of photonic upconversion mechanisms in two-dimensional quantum materials.
Collapse
Affiliation(s)
- Ewa Żuberek
- Department of Experimental Physics, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Martyna Majak
- Department of Experimental Physics, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Jakub Lubczyński
- Department of Experimental Physics, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Joerg Debus
- Department of Physics, TU Dortmund University, 44227 Dortmund, Germany
| | - Kenji Watanabe
- National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 Japan
| | - Takashi Taniguchi
- National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 Japan
| | - Ching-Hwa Ho
- Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei, 106 Taiwan
| | - Leszek Bryja
- Department of Experimental Physics, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Joanna Jadczak
- Department of Experimental Physics, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| |
Collapse
|
7
|
Grzeszczyk M, Olkowska-Pucko K, Nogajewski K, Watanabe K, Taniguchi T, Kossacki P, Babiński A, Molas MR. Exposing the trion's fine structure by controlling the carrier concentration in hBN-encapsulated MoS 2. NANOSCALE 2021; 13:18726-18733. [PMID: 34739017 DOI: 10.1039/d1nr03855a] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Atomically thin materials, like semiconducting transition metal dichalcogenides, are highly sensitive to the environment. This opens up an opportunity to externally control their properties by changing their surroundings. In this work, high-quality van der Waals heterostructures assembled from hBN-encapsulated monolayer MoS2 are studied with the aid of photoluminescence, photoluminescence excitation, and reflectance contrast experiments. We demonstrate that carrier concentration in MoS2 monolayers, arising from charge transfer from impurities in the substrate, can be significantly tuned within one order of magnitude by the modification of the bottom hBN flake thickness. The studied structures, characterized by spectral lines with linewidths approaching the narrow homogeneously broadened limit enabled observations of subtle optical and spin-valley properties of excitonic complexes. Our results allowed us to resolve three optically-active negatively charged excitons in MoS2 monolayers, which are assigned to the intravalley singlet, intervalley singlet, and intervalley triplet states.
Collapse
Affiliation(s)
- Magdalena Grzeszczyk
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, 02-093 Warsaw, Poland.
| | - Katarzyna Olkowska-Pucko
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, 02-093 Warsaw, Poland.
| | - Karol Nogajewski
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, 02-093 Warsaw, Poland.
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 305-0044, Japan
| | - Piotr Kossacki
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, 02-093 Warsaw, Poland.
| | - Adam Babiński
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, 02-093 Warsaw, Poland.
| | - Maciej R Molas
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, 02-093 Warsaw, Poland.
| |
Collapse
|
8
|
Dong HM, Tao ZH, Duan YF, Li LL, Huang F, Peeters FM. Substrate dependent terahertz magneto-optical properties of monolayer WS 2. OPTICS LETTERS 2021; 46:4892-4895. [PMID: 34598227 DOI: 10.1364/ol.435055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 08/31/2021] [Indexed: 06/13/2023]
Abstract
Terahertz (THz) magneto-optical (MO) properties of monolayer (ML) tungsten disulfide (WS2), placed on different substrates and subjected to external magnetic fields, are studied using THz time-domain spectroscopy (TDS). We find that the THz MO conductivity exhibits a nearly linear response in a weak magnetic field, while a distinctly nonlinear/oscillating behavior is found in strong magnetic fields owing to strong substrate-induced random impurity scattering and interactions. The THz MO response of ML WS2 depends sensitively on the choice of the substrates, which we trace back to electronic localization and the impact of the substrates on the Landau level (LL) spectrum. Our results provide an in-depth understanding of the THz MO properties of ML WS2/substrate systems, especially the effect of substrates, which can be utilized to realize atomically thin THz MO nano-devices.
Collapse
|
9
|
Zinkiewicz M, Woźniak T, Kazimierczuk T, Kapuscinski P, Oreszczuk K, Grzeszczyk M, Bartoš M, Nogajewski K, Watanabe K, Taniguchi T, Faugeras C, Kossacki P, Potemski M, Babiński A, Molas MR. Excitonic Complexes in n-Doped WS 2 Monolayer. NANO LETTERS 2021; 21:2519-2525. [PMID: 33683895 PMCID: PMC7995249 DOI: 10.1021/acs.nanolett.0c05021] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 02/22/2021] [Indexed: 05/25/2023]
Abstract
We investigate the origin of emission lines apparent in the low-temperature photoluminescence spectra of n-doped WS2 monolayer embedded in hexagonal BN layers using external magnetic fields and first-principles calculations. Apart from the neutral A exciton line, all observed emission lines are related to the negatively charged excitons. Consequently, we identify emissions due to both the bright (singlet and triplet) and dark (spin- and momentum-forbidden) negative trions as well as the phonon replicas of the latter optically inactive complexes. The semidark trions and negative biexcitons are distinguished. On the basis of their experimentally extracted and theoretically calculated g-factors, we identify three distinct families of emissions due to exciton complexes in WS2: bright, intravalley, and intervalley dark. The g-factors of the spin-split subbands in both the conduction and valence bands are also determined.
Collapse
Affiliation(s)
- Małgorzata Zinkiewicz
- Institute
of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Tomasz Woźniak
- Department
of Semiconductor Materials Engineering, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego
27, 50-370 Wrocław, Poland
| | - Tomasz Kazimierczuk
- Institute
of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Piotr Kapuscinski
- Laboratoire
National des Champs Magnétiques Intenses, CNRS-UGA-UPS-INSA-EMFL, 25, avenue des Martyrs, 38042 Grenoble, France
- Department
of Experimental Physics, Wrocław University
of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370 Wrocław, Poland
| | - Kacper Oreszczuk
- Institute
of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Magdalena Grzeszczyk
- Institute
of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Miroslav Bartoš
- Laboratoire
National des Champs Magnétiques Intenses, CNRS-UGA-UPS-INSA-EMFL, 25, avenue des Martyrs, 38042 Grenoble, France
- Central
European Institute of Technology, Brno University
of Technology, Purkyňova
656/123, 612 00 Brno, Czech Republic
| | - Karol Nogajewski
- Institute
of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Kenji Watanabe
- Research
Center for Functional Materials, National
Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- International
Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Clement Faugeras
- Laboratoire
National des Champs Magnétiques Intenses, CNRS-UGA-UPS-INSA-EMFL, 25, avenue des Martyrs, 38042 Grenoble, France
| | - Piotr Kossacki
- Institute
of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Marek Potemski
- Institute
of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
- Laboratoire
National des Champs Magnétiques Intenses, CNRS-UGA-UPS-INSA-EMFL, 25, avenue des Martyrs, 38042 Grenoble, France
| | - Adam Babiński
- Institute
of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Maciej R. Molas
- Institute
of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| |
Collapse
|
10
|
Investigations of Electron-Electron and Interlayer Electron-Phonon Coupling in van der Waals hBN/WSe 2/hBN Heterostructures by Photoluminescence Excitation Experiments. MATERIALS 2021; 14:ma14020399. [PMID: 33467435 PMCID: PMC7830124 DOI: 10.3390/ma14020399] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 01/10/2021] [Accepted: 01/11/2021] [Indexed: 11/17/2022]
Abstract
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/WSe2/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 (WSe2) + ZO (hBN) are in resonance with the excited (2s) and ground (1s) states of the A exciton in a WSe2 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 WSe2 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 XX0 at double resonance condition is observed for the first time.
Collapse
|
11
|
Zinkiewicz M, Slobodeniuk AO, Kazimierczuk T, Kapuściński P, Oreszczuk K, Grzeszczyk M, Bartos M, Nogajewski K, Watanabe K, Taniguchi T, Faugeras C, Kossacki P, Potemski M, Babiński A, Molas MR. Neutral and charged dark excitons in monolayer WS 2. NANOSCALE 2020; 12:18153-18159. [PMID: 32853305 DOI: 10.1039/d0nr04243a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Low temperature and polarization resolved magneto-photoluminescence experiments are used to investigate the properties of dark excitons and dark trions in a monolayer of WS2 encapsulated in hexagonal BN (hBN). We find that this system is an n-type doped semiconductor and that dark trions dominate the emission spectrum. In line with previous studies on WSe2, we identify the Coulomb exchange interaction coupled neutral dark and grey excitons through their polarization properties, while an analogous effect is not observed for dark trions. Applying the magnetic field in both perpendicular and parallel configurations with respect to the monolayer plane, we determine the g-factor of dark trions to be g ∼ -8.6. Their decay rate is close to 0.5 ns, more than 2 orders of magnitude longer than that of bright excitons.
Collapse
Affiliation(s)
- M Zinkiewicz
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland.
| | - A O Slobodeniuk
- Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 5, Praha 2 CZ-121 16, Czech Republic
| | - T Kazimierczuk
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland.
| | - P Kapuściński
- Laboratoire National des Champs Magnétiques Intenses, CNRS-UGA-UPS-INSA-EMFL, 25, avenue des Martyrs, 38042 Grenoble, France and Department of Experimental Physics, Faculty of Fundamental Problems of Technology, Wrocław University of Science and Technology, ul. Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - K Oreszczuk
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland.
| | - M Grzeszczyk
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland.
| | - M Bartos
- Laboratoire National des Champs Magnétiques Intenses, CNRS-UGA-UPS-INSA-EMFL, 25, avenue des Martyrs, 38042 Grenoble, France and Central European Institute of Technology, Brno University of Technology, Purkyňova 656/123, 612 00 Brno, Czech Republic
| | - K Nogajewski
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland.
| | - K Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - T Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - C Faugeras
- Laboratoire National des Champs Magnétiques Intenses, CNRS-UGA-UPS-INSA-EMFL, 25, avenue des Martyrs, 38042 Grenoble, France
| | - P Kossacki
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland.
| | - M Potemski
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland. and Laboratoire National des Champs Magnétiques Intenses, CNRS-UGA-UPS-INSA-EMFL, 25, avenue des Martyrs, 38042 Grenoble, France
| | - A Babiński
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland.
| | - M R Molas
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland.
| |
Collapse
|