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Kumar AM, Yagodkin D, Rosati R, Bock DJ, Schattauer C, Tobisch S, Hagel J, Höfer B, Kirchhof JN, Hernández López P, Burfeindt K, Heeg S, Gahl C, Libisch F, Malic E, Bolotin KI. Strain fingerprinting of exciton valley character in 2D semiconductors. Nat Commun 2024; 15:7546. [PMID: 39214968 PMCID: PMC11364664 DOI: 10.1038/s41467-024-51195-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Accepted: 07/30/2024] [Indexed: 09/04/2024] Open
Abstract
Intervalley excitons with electron and hole wavefunctions residing in different valleys determine the long-range transport and dynamics observed in many semiconductors. However, these excitons with vanishing oscillator strength do not directly couple to light and, hence, remain largely unstudied. Here, we develop a simple nanomechanical technique to control the energy hierarchy of valleys via their contrasting response to mechanical strain. We use our technique to discover previously inaccessible intervalley excitons associated with K, Γ, or Q valleys in prototypical 2D semiconductors WSe2 and WS2. We also demonstrate a new brightening mechanism, rendering an otherwise "dark" intervalley exciton visible via strain-controlled hybridization with an intravalley exciton. Moreover, we classify various localized excitons from their distinct strain response and achieve large tuning of their energy. Overall, our valley engineering approach establishes a new way to identify intervalley excitons and control their interactions in a diverse class of 2D systems.
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Affiliation(s)
- Abhijeet M Kumar
- Department of Physics, Freie Universität Berlin, Arnimallee 14, Berlin, Germany
| | - Denis Yagodkin
- Department of Physics, Freie Universität Berlin, Arnimallee 14, Berlin, Germany
| | - Roberto Rosati
- Philipps-Universität Marburg, Mainzer Gasse 33, Marburg, Germany
| | - Douglas J Bock
- Department of Physics, Freie Universität Berlin, Arnimallee 14, Berlin, Germany
| | - Christoph Schattauer
- Institute for Theoretical Physics, TU Wien, Wiedner Hauptstraße 8-10, Vienna, Austria
| | - Sarah Tobisch
- Institute for Theoretical Physics, TU Wien, Wiedner Hauptstraße 8-10, Vienna, Austria
| | - Joakim Hagel
- Department of Physics, Chalmers University of Technology, 412 96 Gothenburg, Gothenburg, Sweden
| | - Bianca Höfer
- Department of Physics, Freie Universität Berlin, Arnimallee 14, Berlin, Germany
| | - Jan N Kirchhof
- Department of Physics, Freie Universität Berlin, Arnimallee 14, Berlin, Germany
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Delft, The Netherlands
| | - Pablo Hernández López
- Institute for Physics and IRIS Adlershof, Humboldt-Universität Berlin, Newtonstraße 15, Berlin, Germany
| | - Kenneth Burfeindt
- Department of Physics, Freie Universität Berlin, Arnimallee 14, Berlin, Germany
| | - Sebastian Heeg
- Institute for Physics and IRIS Adlershof, Humboldt-Universität Berlin, Newtonstraße 15, Berlin, Germany
| | - Cornelius Gahl
- Department of Physics, Freie Universität Berlin, Arnimallee 14, Berlin, Germany
| | - Florian Libisch
- Institute for Theoretical Physics, TU Wien, Wiedner Hauptstraße 8-10, Vienna, Austria
| | - Ermin Malic
- Philipps-Universität Marburg, Mainzer Gasse 33, Marburg, Germany
| | - Kirill I Bolotin
- Department of Physics, Freie Universität Berlin, Arnimallee 14, Berlin, Germany.
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2
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Shen K, Sun K, Gelin MF, Zhao Y. Cavity-Tuned Exciton Dynamics in Transition Metal Dichalcogenides Monolayers. MATERIALS (BASEL, SWITZERLAND) 2024; 17:4127. [PMID: 39203305 PMCID: PMC11356741 DOI: 10.3390/ma17164127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2024] [Revised: 08/09/2024] [Accepted: 08/16/2024] [Indexed: 09/03/2024]
Abstract
A fully quantum, numerically accurate methodology is presented for the simulation of the exciton dynamics and time-resolved fluorescence of cavity-tuned two-dimensional (2D) materials at finite temperatures. This approach was specifically applied to a monolayer WSe2 system. Our methodology enabled us to identify the dynamical and spectroscopic signatures of polaronic and polaritonic effects and to elucidate their characteristic timescales across a range of exciton-cavity couplings. The approach employed can be extended to simulation of various cavity-tuned 2D materials, specifically for exploring finite temperature nonlinear spectroscopic signals.
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Affiliation(s)
- Kaijun Shen
- School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Kewei Sun
- School of Science, Hangzhou Dianzi University, Hangzhou 310018, China
| | - Maxim F. Gelin
- School of Science, Hangzhou Dianzi University, Hangzhou 310018, China
| | - Yang Zhao
- School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore
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3
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He X, Zhong X, Si W, Zhao Z, Wang H, Zhang X, Xie Y. Interior Exciton Extraction by Spatial-Controlled Iodine Doping in BiOBr Photocatalysts. NANO LETTERS 2024; 24:6545-6552. [PMID: 38781416 DOI: 10.1021/acs.nanolett.4c00951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2024]
Abstract
Extracting interior photoinduced species to the surface before their recombination is of great importance in pursuing high-efficiency semiconductor-based photocatalysis. Traditional strategies toward charge-carrier extraction, mostly relying on the construction of an electric field gradient, would be invalid toward the neutral-exciton counterpart in low-dimensional systems. In this work, by taking bismuth oxybromide (BiOBr) as an example, we manipulate interior exciton extraction to the surface by implementing iodine doping at the edges of BiOBr plates. Spatial- and time-resolved spectroscopic analyses verified the accumulation of excitons and charge carriers at the edges of iodine-doped BiOBr (BiOBr-I) plates. This phenomenon could be associated with interior exciton extraction, driven by an energy-level gradient between interior and edge exciton states, and the following exciton dissociation processes. As such, BiOBr-I shows remarkable performance in photocatalytic C-H fluorination, mediated by both energy- and charge-transfer processes. This work uncovers the importance of spatial regulation of excitonic properties in low-dimensional semiconductor-based photocatalysis.
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Affiliation(s)
- Xin He
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China Hefei, Anhui 230026, China
| | - Xia Zhong
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China Hefei, Anhui 230026, China
| | - Wen Si
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China Hefei, Anhui 230026, China
| | - Zhi Zhao
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China Hefei, Anhui 230026, China
| | - Hui Wang
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China Hefei, Anhui 230026, China
| | - Xiaodong Zhang
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China Hefei, Anhui 230026, China
| | - Yi Xie
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China Hefei, Anhui 230026, China
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4
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Xu DD, Vong AF, Utama MIB, Lebedev D, Ananth R, Hersam MC, Weiss EA, Mirkin CA. Sub-Diffraction Correlation of Quantum Emitters and Local Strain Fields in Strain-Engineered WSe 2 Monolayers. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2314242. [PMID: 38346232 DOI: 10.1002/adma.202314242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Indexed: 03/27/2024]
Abstract
Strain-engineering in atomically thin metal dichalcogenides is a useful method for realizing single-photon emitters (SPEs) for quantum technologies. Correlating SPE position with local strain topography is challenging due to localization inaccuracies from the diffraction limit. Currently, SPEs are assumed to be positioned at the highest strained location and are typically identified by randomly screening narrow-linewidth emitters, of which only a few are spectrally pure. In this work, hyperspectral quantum emitter localization microscopy is used to locate 33 SPEs in nanoparticle-strained WSe2 monolayers with sub-diffraction-limit resolution (≈30 nm) and correlate their positions with the underlying strain field via image registration. In this system, spectrally pure emitters are not concentrated at the highest strain location due to spectral contamination; instead, isolable SPEs are distributed away from points of peak strain with an average displacement of 240 nm. These observations point toward a need for a change in the design rules for strain-engineered SPEs and constitute a key step toward realizing next-generation quantum optical architectures.
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Affiliation(s)
- David D Xu
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
- International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Albert F Vong
- International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
- Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, IL, 60208, USA
| | - M Iqbal Bakti Utama
- Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, IL, 60208, USA
| | - Dmitry Lebedev
- Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, IL, 60208, USA
| | - Riddhi Ananth
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
- International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Mark C Hersam
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
- International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
- Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, IL, 60208, USA
- Department of Electrical and Computer Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Emily A Weiss
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
- International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
- Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, IL, 60208, USA
| | - Chad A Mirkin
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
- International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
- Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, IL, 60208, USA
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5
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Knorr W, Brem S, Meneghini G, Malic E. Polaron-induced changes in moiré exciton propagation in twisted van der Waals heterostructures. NANOSCALE 2024. [PMID: 38623653 DOI: 10.1039/d4nr00136b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/17/2024]
Abstract
Twisted transition metal dichalcogenides (TMDs) present an intriguing platform for exploring excitons and their transport properties. By introducing a twist angle, a moiré superlattice forms, providing a spatially dependent exciton energy landscape. Based on a microscopic many-particle theory, we investigate in this work polaron-induced changes in exciton transport properties in the exemplary MoSe2/WSe2 heterostructure. We demonstrate that polaron formation and the associated enhancement of the moiré exciton mass lead to a significant band flattening. As a result, the moiré inter-cell tunneling and the propagation velocity undergo noticeable temperature and twist-angle dependent changes. We predict a reduction of the hopping strength ranging from 80% at a twist angle of 1° to 30% at 3° at room temperature. The provided microscopic insights into the spatio-temporal exciton dynamics in presence of a moiré potential further expand the possibilities to tune charge and energy transport in 2D materials.
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Affiliation(s)
- Willy Knorr
- Department of Physics, Philipps University, 35037 Marburg, Germany.
| | - Samuel Brem
- Department of Physics, Philipps University, 35037 Marburg, Germany.
| | | | - Ermin Malic
- Department of Physics, Philipps University, 35037 Marburg, Germany.
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6
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Wang J, He L, Zhang Y, Nong H, Li S, Wu Q, Tan J, Liu B. Locally Strained 2D Materials: Preparation, Properties, and Applications. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2314145. [PMID: 38339886 DOI: 10.1002/adma.202314145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2023] [Revised: 01/28/2024] [Indexed: 02/12/2024]
Abstract
2D materials are promising for strain engineering due to their atomic thickness and exceptional mechanical properties. In particular, non-uniform and localized strain can be induced in 2D materials by generating out-of-plane deformations, resulting in novel phenomena and properties, as witnessed in recent years. Therefore, the locally strained 2D materials are of great value for both fundamental studies and practical applications. This review discusses techniques for introducing local strains to 2D materials, and their feasibility, advantages, and challenges. Then, the unique effects and properties that arise from local strain are explored. The representative applications based on locally strained 2D materials are illustrated, including memristor, single photon emitter, and photodetector. Finally, concluding remarks on the challenges and opportunities in the emerging field of locally strained 2D materials are provided.
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Affiliation(s)
- Jingwei Wang
- Shenzhen Geim Graphene Center, Tsinghua-Berkeley Shenzhen Institute and Institute of Materials Research, Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, P. R. China
| | - Liqiong He
- Shenzhen Geim Graphene Center, Tsinghua-Berkeley Shenzhen Institute and Institute of Materials Research, Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, P. R. China
| | - Yunhao Zhang
- Shenzhen Geim Graphene Center, Tsinghua-Berkeley Shenzhen Institute and Institute of Materials Research, Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, P. R. China
| | - Huiyu Nong
- Shenzhen Geim Graphene Center, Tsinghua-Berkeley Shenzhen Institute and Institute of Materials Research, Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, P. R. China
| | - Shengnan Li
- Shenzhen Geim Graphene Center, Tsinghua-Berkeley Shenzhen Institute and Institute of Materials Research, Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, P. R. China
| | - Qinke Wu
- Shenzhen Geim Graphene Center, Tsinghua-Berkeley Shenzhen Institute and Institute of Materials Research, Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, P. R. China
| | - Junyang Tan
- Shenzhen Geim Graphene Center, Tsinghua-Berkeley Shenzhen Institute and Institute of Materials Research, Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, P. R. China
| | - Bilu Liu
- Shenzhen Geim Graphene Center, Tsinghua-Berkeley Shenzhen Institute and Institute of Materials Research, Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, P. R. China
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7
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Park S, Kim J, Kim D, Watanabe K, Taniguchi T, Seo MK. Demonstration of Two-Dimensional Exciton Complex Palette. ACS NANO 2024. [PMID: 38335539 DOI: 10.1021/acsnano.3c11214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2024]
Abstract
Exciton complexes in two-dimensional semiconductors, encompassing bright and dark excitons, biexcitons, and defect-bound excitons, have shown significant potential across a wide range of research areas. These applications range from exploring quantum many-body phenomena to developing nonclassical light sources and quantum transport devices. To fully leverage their dynamic and interactive properties and extend the capabilities of excitonic devices, realizing systematic engineering and mixing of the exciton complexes are crucial. Unlike conventional material methods, which often lead to undesired changes in the electronic band structure and binding energy, optical methods provide a means to manipulate the radiative decay dynamics of individual exciton complexes in a purely environmental manner. Here, we employ a specialized photonic platform, analogous to an artist's palette, to arrange and mix exciton complexes on an identical two-dimensional transition metal dichalcogenide medium. Essentially, a gradient thickness mirror (GTM) continuously tunes the local distribution of optical vacuum field interference. The GTM platform enables us to create and examine five distinct compositions of the exciton complexes of the WSe2 monolayer and their contributions to the photoluminescence spectrum. Moreover, the exciton complex palette facilitates the observation of dark and defect-bound excitons, even at high temperatures of 70 K, and its performance can be further managed by simple postprocessing manipulations.
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Affiliation(s)
- Sanghyeok Park
- Department of Physics, KAIST, Daejeon, Daehak-ro, 291, 34141, Republic of Korea
| | - Jaeyu Kim
- Department of Physics, KAIST, Daejeon, Daehak-ro, 291, 34141, Republic of Korea
| | - Dongha Kim
- Department of Physics, KAIST, Daejeon, Daehak-ro, 291, 34141, Republic of Korea
| | - Kenji Watanabe
- Research Center for Electronic and Optical Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Min-Kyo Seo
- Department of Physics, KAIST, Daejeon, Daehak-ro, 291, 34141, Republic of Korea
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8
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Dai B, Su Y, Guo Y, Wu C, Xie Y. Recent Strategies for the Synthesis of Phase-Pure Ultrathin 1T/1T' Transition Metal Dichalcogenide Nanosheets. Chem Rev 2024; 124:420-454. [PMID: 38146851 DOI: 10.1021/acs.chemrev.3c00422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2023]
Abstract
The past few decades have witnessed a notable increase in transition metal dichalcogenide (TMD) related research not only because of the large family of TMD candidates but also because of the various polytypes that arise from the monolayer configuration and layer stacking order. The peculiar physicochemical properties of TMD nanosheets enable an enormous range of applications from fundamental science to industrial technologies based on the preparation of high-quality TMDs. For polymorphic TMDs, the 1T/1T' phase is particularly intriguing because of the enriched density of states, and thus facilitates fruitful chemistry. Herein, we comprehensively discuss the most recent strategies for direct synthesis of phase-pure 1T/1T' TMD nanosheets such as mechanical exfoliation, chemical vapor deposition, wet chemical synthesis, atomic layer deposition, and more. We also review frequently adopted methods for phase engineering in TMD nanosheets ranging from chemical doping and alloying, to charge injection, and irradiation with optical or charged particle beams. Prior to the synthesis methods, we discuss the configuration of TMDs as well as the characterization tools mostly used in experiments. Finally, we discuss the current challenges and opportunities as well as emphasize the promising fields for the future development.
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Affiliation(s)
- Baohu Dai
- Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Yueqi Su
- Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Yuqiao Guo
- Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Changzheng Wu
- Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Yi Xie
- Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
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9
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Gauriot N, Ashoka A, Lim J, See ST, Sung J, Rao A. Direct Imaging of Carrier Funneling in a Dielectric Engineered 2D Semiconductor. ACS NANO 2024; 18:264-271. [PMID: 38196169 PMCID: PMC10786151 DOI: 10.1021/acsnano.3c05957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 11/23/2023] [Accepted: 12/01/2023] [Indexed: 01/11/2024]
Abstract
In atomically thin transition-metal dichalcogenides (TMDCs), the environmental sensitivity of the strong Coulomb interaction offers promising approaches to create spatially varying potential landscapes in the same continuous material by tuning its dielectric environment. Thus, allowing for control of transport. However, a scalable and CMOS-compatible method for achieving this is required to harness these effects in practical applications. In addition, because of their ultrashort lifetime, observing the spatiotemporal dynamics of carriers in monolayer TMDCs, on the relevant time scale, is challenging. Here, we pattern and deposit a thin film of hafnium oxide (HfO2) via atomic layer deposition (ALD) on top of a monolayer of WSe2. This allows for the engineering of the dielectric environment of the monolayer and design of heterostructures with nanoscale spatial resolution via a highly scalable postsynthesis methodology. We then directly image the transport of photoexcitations in the monolayer with 50 fs time resolution and few-nanometer spatial precision, using a pump probe microscopy technique. We observe the unidirectional funneling of charge carriers, from the unpatterned to the patterned areas, over more than 50 nm in the first 20 ps with velocities of over 2 × 103 m/s at room temperature. These results demonstrate the possibilities offered by dielectric engineering via ALD patterning, allowing for arbitrary spatial patterns that define the potential landscape and allow for control of the transport of excitations in atomically thin materials. This work also shows the power of the transient absorption methodology to image the motion of photoexcited states in complex potential landscapes on ultrafast time scales.
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Affiliation(s)
- Nicolas Gauriot
- Cavendish
Laboratory, University of Cambridge, CB3 0HE Cambridge, United Kingdom
| | - Arjun Ashoka
- Cavendish
Laboratory, University of Cambridge, CB3 0HE Cambridge, United Kingdom
| | - Juhwan Lim
- Cavendish
Laboratory, University of Cambridge, CB3 0HE Cambridge, United Kingdom
| | - Soo Teck See
- Cavendish
Laboratory, University of Cambridge, CB3 0HE Cambridge, United Kingdom
| | - Jooyoung Sung
- Cavendish
Laboratory, University of Cambridge, CB3 0HE Cambridge, United Kingdom
- Department
of Physics and Chemistry, DGIST, Daegu 42988, Republic of Korea
| | - Akshay Rao
- Cavendish
Laboratory, University of Cambridge, CB3 0HE Cambridge, United Kingdom
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Lee H, Kim YB, Ryu JW, Kim S, Bae J, Koo Y, Jang D, Park KD. Recent progress of exciton transport in two-dimensional semiconductors. NANO CONVERGENCE 2023; 10:57. [PMID: 38102309 PMCID: PMC10724105 DOI: 10.1186/s40580-023-00404-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 11/20/2023] [Indexed: 12/17/2023]
Abstract
Spatial manipulation of excitonic quasiparticles, such as neutral excitons, charged excitons, and interlayer excitons, in two-dimensional semiconductors offers unique capabilities for a broad range of optoelectronic applications, encompassing photovoltaics, exciton-integrated circuits, and quantum light-emitting systems. Nonetheless, their practical implementation is significantly restricted by the absence of electrical controllability for neutral excitons, short lifetime of charged excitons, and low exciton funneling efficiency at room temperature, which remain a challenge in exciton transport. In this comprehensive review, we present the latest advancements in controlling exciton currents by harnessing the advanced techniques and the unique properties of various excitonic quasiparticles. We primarily focus on four distinct control parameters inducing the exciton current: electric fields, strain gradients, surface plasmon polaritons, and photonic cavities. For each approach, the underlying principles are introduced in conjunction with its progression through recent studies, gradually expanding their accessibility, efficiency, and functionality. Finally, we outline the prevailing challenges to fully harness the potential of excitonic quasiparticles and implement practical exciton-based optoelectronic devices.
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Affiliation(s)
- Hyeongwoo Lee
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Yong Bin Kim
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Jae Won Ryu
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Sujeong Kim
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Jinhyuk Bae
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Yeonjeong Koo
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Donghoon Jang
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Kyoung-Duck Park
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea.
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Naumis GG, Herrera SA, Poudel SP, Nakamura H, Barraza-Lopez S. Mechanical, electronic, optical, piezoelectric and ferroic properties of strained graphene and other strained monolayers and multilayers: an update. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2023; 87:016502. [PMID: 37879327 DOI: 10.1088/1361-6633/ad06db] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 10/25/2023] [Indexed: 10/27/2023]
Abstract
This is an update of a previous review (Naumiset al2017Rep. Prog. Phys.80096501). Experimental and theoretical advances for straining graphene and other metallic, insulating, ferroelectric, ferroelastic, ferromagnetic and multiferroic 2D materials were considered. We surveyed (i) methods to induce valley and sublattice polarisation (P) in graphene, (ii) time-dependent strain and its impact on graphene's electronic properties, (iii) the role of local and global strain on superconductivity and other highly correlated and/or topological phases of graphene, (iv) inducing polarisationPon hexagonal boron nitride monolayers via strain, (v) modifying the optoelectronic properties of transition metal dichalcogenide monolayers through strain, (vi) ferroic 2D materials with intrinsic elastic (σ), electric (P) and magnetic (M) polarisation under strain, as well as incipient 2D multiferroics and (vii) moiré bilayers exhibiting flat electronic bands and exotic quantum phase diagrams, and other bilayer or few-layer systems exhibiting ferroic orders tunable by rotations and shear strain. The update features the experimental realisations of a tunable two-dimensional Quantum Spin Hall effect in germanene, of elemental 2D ferroelectric bismuth, and 2D multiferroic NiI2. The document was structured for a discussion of effects taking place in monolayers first, followed by discussions concerning bilayers and few-layers, and it represents an up-to-date overview of exciting and newest developments on the fast-paced field of 2D materials.
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Affiliation(s)
- Gerardo G Naumis
- Departamento de Sistemas Complejos, Instituto de Física, Universidad Nacional Autónoma de México (UNAM), Apdo. Postal 20-364, CDMX, 01000, Mexico
| | - Saúl A Herrera
- Departamento de Sistemas Complejos, Instituto de Física, Universidad Nacional Autónoma de México (UNAM), Apdo. Postal 20-364, CDMX, 01000, Mexico
| | - Shiva P Poudel
- Department of Physics, University of Arkansas, Fayetteville, AR 72701, United States of America
- MonArk NSF Quantum Foundry, University of Arkansas, Fayetteville, AR 72701, United States of America
| | - Hiro Nakamura
- Department of Physics, University of Arkansas, Fayetteville, AR 72701, United States of America
- MonArk NSF Quantum Foundry, University of Arkansas, Fayetteville, AR 72701, United States of America
| | - Salvador Barraza-Lopez
- Department of Physics, University of Arkansas, Fayetteville, AR 72701, United States of America
- MonArk NSF Quantum Foundry, University of Arkansas, Fayetteville, AR 72701, United States of America
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12
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Li Z, Florian M, Datta K, Jiang Z, Borsch M, Wen Q, Kira M, Deotare PB. Enhanced Exciton Drift Transport through Suppressed Diffusion in One-Dimensional Guides. ACS NANO 2023; 17:22410-22417. [PMID: 37874891 DOI: 10.1021/acsnano.3c04870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2023]
Abstract
Drift-diffusion dynamics is investigated in a one-dimensional (1D) exciton guide at room temperature. Spatial engineering of the exciton energy in a WSe2 monolayer is achieved using local strain to confine and direct exciton transport. An unexpected and massive deviation from the Einstein relation is observed and correlated to exciton capture by defects. We find that the capture reduces exciton temperature and diffusion so much that drift transport visibility improves to 38% as excitons traverse asymmetrically over regions with occupied defect states. Based on measurements over multiple potential gradients, we estimate the exciton mobility to be 169 ± 39 cm2/(eV s) at room temperature. Experiments at elevated exciton densities reveal that the exciton drift velocity monotonically increases with exciton density, unlike exciton mobility, due to contributions from nonequilibrium many-body effects.
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Affiliation(s)
- Zidong Li
- Electrical and Computer Engineering Department, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Matthias Florian
- Electrical and Computer Engineering Department, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Kanak Datta
- Electrical and Computer Engineering Department, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Zhaohan Jiang
- Electrical and Computer Engineering Department, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Markus Borsch
- Electrical and Computer Engineering Department, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Qiannan Wen
- Electrical and Computer Engineering Department, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Mack Kira
- Electrical and Computer Engineering Department, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Parag B Deotare
- Electrical and Computer Engineering Department, University of Michigan, Ann Arbor, Michigan 48109, United States
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13
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Yagodkin D, Kumar A, Ankerhold E, Richter J, Watanabe K, Taniguchi T, Gahl C, Bolotin KI. Probing the Formation of Dark Interlayer Excitons via Ultrafast Photocurrent. NANO LETTERS 2023; 23:9212-9218. [PMID: 37788809 PMCID: PMC10603811 DOI: 10.1021/acs.nanolett.3c01708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 08/15/2023] [Indexed: 10/05/2023]
Abstract
Optically dark excitons determine a wide range of properties of photoexcited semiconductors yet are hard to access via conventional time-resolved spectroscopies. Here, we develop a time-resolved ultrafast photocurrent technique (trPC) to probe the formation dynamics of optically dark excitons. The nonlinear nature of the trPC makes it particularly sensitive to the formation of excitons occurring at the femtosecond time scale after the excitation. As a proof of principle, we extract the interlayer exciton formation time of 0.4 ps at 160 μJ/cm2 fluence in a MoS2/MoSe2 heterostructure and show that this time decreases with fluence. In addition, our approach provides access to the dynamics of carriers and their interlayer transport. Overall, our work establishes trPC as a technique to study dark excitons in various systems that are hard to probe by other approaches.
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Affiliation(s)
- Denis Yagodkin
- Department
of Physics, Freie Universität Berlin, Arnimallee 14, Berlin 14195, Germany
| | - Abhijeet Kumar
- Department
of Physics, Freie Universität Berlin, Arnimallee 14, Berlin 14195, Germany
| | - Elias Ankerhold
- Department
of Physics, Freie Universität Berlin, Arnimallee 14, Berlin 14195, Germany
| | - Johanna Richter
- Department
of Physics, Freie Universität Berlin, Arnimallee 14, Berlin 14195, Germany
| | - 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
| | - Cornelius Gahl
- Department
of Physics, Freie Universität Berlin, Arnimallee 14, Berlin 14195, Germany
| | - Kirill I. Bolotin
- Department
of Physics, Freie Universität Berlin, Arnimallee 14, Berlin 14195, Germany
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14
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Sortino L, Gülmüs M, Tilmann B, de S Menezes L, Maier SA. Radiative suppression of exciton-exciton annihilation in a two-dimensional semiconductor. LIGHT, SCIENCE & APPLICATIONS 2023; 12:202. [PMID: 37620298 PMCID: PMC10449935 DOI: 10.1038/s41377-023-01249-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 07/25/2023] [Accepted: 07/30/2023] [Indexed: 08/26/2023]
Abstract
Two-dimensional (2D) semiconductors possess strongly bound excitons, opening novel opportunities for engineering light-matter interaction at the nanoscale. However, their in-plane confinement leads to large non-radiative exciton-exciton annihilation (EEA) processes, setting a fundamental limit for their photonic applications. In this work, we demonstrate suppression of EEA via enhancement of light-matter interaction in hybrid 2D semiconductor-dielectric nanophotonic platforms, by coupling excitons in WS2 monolayers with optical Mie resonances in dielectric nanoantennas. The hybrid system reaches an intermediate light-matter coupling regime, with photoluminescence enhancement factors up to 102. Probing the exciton ultrafast dynamics reveal suppressed EEA for coupled excitons, even under high exciton densities >1012 cm-2. We extract EEA coefficients in the order of 10-3, compared to 10-2 for uncoupled monolayers, as well as a Purcell factor of 4.5. Our results highlight engineering the photonic environment as a route to achieve higher quantum efficiencies, for low-power hybrid devices, and larger exciton densities, towards strongly correlated excitonic phases in 2D semiconductors.
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Affiliation(s)
- Luca Sortino
- Chair in Hybrid Nanosystems, Nanoinstitute Munich, Faculty of Physics, Ludwig-Maximilians-Universität München, 80539, Munich, Germany.
- Center for NanoScience, Faculty of Physics, Ludwig-Maximilians-Universität München, 80539, Munich, Germany.
| | - Merve Gülmüs
- Chair in Hybrid Nanosystems, Nanoinstitute Munich, Faculty of Physics, Ludwig-Maximilians-Universität München, 80539, Munich, Germany
| | - Benjamin Tilmann
- Chair in Hybrid Nanosystems, Nanoinstitute Munich, Faculty of Physics, Ludwig-Maximilians-Universität München, 80539, Munich, Germany
- Center for NanoScience, Faculty of Physics, Ludwig-Maximilians-Universität München, 80539, Munich, Germany
| | - Leonardo de S Menezes
- Chair in Hybrid Nanosystems, Nanoinstitute Munich, Faculty of Physics, Ludwig-Maximilians-Universität München, 80539, Munich, Germany
- Center for NanoScience, Faculty of Physics, Ludwig-Maximilians-Universität München, 80539, Munich, Germany
- Departamento de Física, Universidade Federal de Pernambuco, 50670-901, Recife-PE, Brazil
| | - Stefan A Maier
- Chair in Hybrid Nanosystems, Nanoinstitute Munich, Faculty of Physics, Ludwig-Maximilians-Universität München, 80539, Munich, Germany
- Center for NanoScience, Faculty of Physics, Ludwig-Maximilians-Universität München, 80539, Munich, Germany
- School of Physics and Astronomy, Monash University, Clayton, VIC, 3800, Australia
- The Blackett Laboratory, Department of Physics, Imperial College London, London, SW7 2BW, UK
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15
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Erkensten D, Brem S, Perea-Causín R, Hagel J, Tagarelli F, Lopriore E, Kis A, Malic E. Electrically tunable dipolar interactions between layer-hybridized excitons. NANOSCALE 2023; 15:11064-11071. [PMID: 37309577 PMCID: PMC10324325 DOI: 10.1039/d3nr01049j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 06/02/2023] [Indexed: 06/14/2023]
Abstract
Transition-metal dichalcogenide bilayers exhibit a rich exciton landscape including layer-hybridized excitons, i.e. excitons which are of partly intra- and interlayer nature. In this work, we study hybrid exciton-exciton interactions in naturally stacked WSe2 homobilayers. In these materials, the exciton landscape is electrically tunable such that the low-energy states can be rendered more or less interlayer-like depending on the strength of the external electric field. Based on a microscopic and material-specific many-particle theory, we reveal two intriguing interaction regimes: a low-dipole regime at small electric fields and a high-dipole regime at larger fields, involving interactions between hybrid excitons with a substantially different intra- and interlayer composition in the two regimes. While the low-dipole regime is characterized by weak inter-excitonic interactions between intralayer-like excitons, the high-dipole regime involves mostly interlayer-like excitons which display a strong dipole-dipole repulsion and give rise to large spectral blue-shifts and a highly anomalous diffusion. Overall, our microscopic study sheds light on the remarkable electrical tunability of hybrid exciton-exciton interactions in atomically thin semiconductors and can guide future experimental studies in this growing field of research.
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Affiliation(s)
- Daniel Erkensten
- Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden.
| | - Samuel Brem
- Department of Physics, Philipps-Universität Marburg, 35037 Marburg, Germany
| | - Raül Perea-Causín
- Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden.
| | - Joakim Hagel
- Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden.
| | - Fedele Tagarelli
- Institute of Electrical and Microengineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Institute of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Edoardo Lopriore
- Institute of Electrical and Microengineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Institute of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Andras Kis
- Institute of Electrical and Microengineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Institute of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Ermin Malic
- Department of Physics, Philipps-Universität Marburg, 35037 Marburg, Germany
- Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden.
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16
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Chand SB, Woods JM, Quan J, Mejia E, Taniguchi T, Watanabe K, Alù A, Grosso G. Interaction-driven transport of dark excitons in 2D semiconductors with phonon-mediated optical readout. Nat Commun 2023; 14:3712. [PMID: 37349290 DOI: 10.1038/s41467-023-39339-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 06/08/2023] [Indexed: 06/24/2023] Open
Abstract
The growing field of quantum information technology requires propagation of information over long distances with efficient readout mechanisms. Excitonic quantum fluids have emerged as a powerful platform for this task due to their straightforward electro-optical conversion. In two-dimensional transition metal dichalcogenides, the coupling between spin and valley provides exciting opportunities for harnessing, manipulating, and storing bits of information. However, the large inhomogeneity of single layers cannot be overcome by the properties of bright excitons, hindering spin-valley transport. Nonetheless, the rich band structure supports dark excitonic states with strong binding energy and longer lifetime, ideally suited for long-range transport. Here we show that dark excitons can diffuse over several micrometers and prove that this repulsion-driven propagation is robust across non-uniform samples. The long-range propagation of dark states with an optical readout mediated by chiral phonons provides a new concept of excitonic devices for applications in both classical and quantum information technology.
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Affiliation(s)
- Saroj B Chand
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York, NY, 10031, USA
| | - John M Woods
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York, NY, 10031, USA
| | - Jiamin Quan
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York, NY, 10031, USA
| | - Enrique Mejia
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York, NY, 10031, USA
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Andrea Alù
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York, NY, 10031, USA
- Department of Electrical Engineering, City College of the City University of New York, New York, NY, 10031, USA
- Physics Program, Graduate Center, City University of New York, New York, NY, 10016, USA
| | - Gabriele Grosso
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York, NY, 10031, USA.
- Physics Program, Graduate Center, City University of New York, New York, NY, 10016, USA.
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17
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Malic E, Perea-Causin R, Rosati R, Erkensten D, Brem S. Exciton transport in atomically thin semiconductors. Nat Commun 2023; 14:3430. [PMID: 37301820 PMCID: PMC10257678 DOI: 10.1038/s41467-023-38556-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 05/09/2023] [Indexed: 06/12/2023] Open
Abstract
In this Comment, the authors discuss the current status, the challenges, and potential technological impact of exciton transport in transition metal dichalcogenide (TMD) monolayers, lateral and vertical heterostructures as well as moiré excitons in twisted TMD heterostacks.
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Affiliation(s)
- Ermin Malic
- Department of Physics, Philipps-Universität Marburg, 35032, Marburg, Germany.
| | - Raül Perea-Causin
- Department of Physics, Chalmers University of Technology, 412 96, Gothenburg, Sweden
| | - Roberto Rosati
- Department of Physics, Philipps-Universität Marburg, 35032, Marburg, Germany
| | - Daniel Erkensten
- Department of Physics, Chalmers University of Technology, 412 96, Gothenburg, Sweden
| | - Samuel Brem
- Department of Physics, Philipps-Universität Marburg, 35032, Marburg, Germany
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18
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Lee S, Choi WH, Cho H, Lee SH, Choi W, Joo J, Lee D, Gong SH. Electric-Field-Driven Trion Drift and Funneling in MoSe 2 Monolayer. NANO LETTERS 2023; 23:4282-4289. [PMID: 37167152 PMCID: PMC10215787 DOI: 10.1021/acs.nanolett.3c00460] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Revised: 05/08/2023] [Indexed: 05/13/2023]
Abstract
Excitons, electron-hole pairs in semiconductors, can be utilized as information carriers with a spin or valley degree of freedom. However, manipulation of excitons' motion is challenging because of their charge-neutral characteristic and short recombination lifetimes. Here we demonstrate electric-field-driven drift and funneling of charged excitons (i.e., trions) toward the center of a MoSe2 monolayer. Using a simple bottom-gate device, we control the electric fields in the vicinity of the suspended monolayer, which increases the trion density and pulls down the layer. We observe that locally excited trions are subjected to electric force and, consequently, drift toward the center of the stretched layer. The exerting electric force on the trion is estimated to be 102-104 times stronger than the strain-induced force in the stretched monolayer, leading to the successful observation of trion drift under continuous-wave excitation. Our findings provide a new route for manipulating trions and achieving new types of optoelectronic devices.
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Affiliation(s)
- Seong
Won Lee
- Department
of Physics, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
- KU
Photonics Center, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Woo Hun Choi
- Department
of Physics, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
- KU
Photonics Center, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - HyunHee Cho
- Department
of Physics, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Sang-hun Lee
- Department
of Physics, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Wookyoung Choi
- Department
of Physics, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Jinsoo Joo
- Department
of Physics, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Donghun Lee
- Department
of Physics, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Su-Hyun Gong
- Department
of Physics, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
- KU
Photonics Center, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
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19
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Choi J, Embley J, Blach DD, Perea-Causín R, Erkensten D, Kim DS, Yuan L, Yoon WY, Taniguchi T, Watanabe K, Ueno K, Tutuc E, Brem S, Malic E, Li X, Huang L. Fermi Pressure and Coulomb Repulsion Driven Rapid Hot Plasma Expansion in a van der Waals Heterostructure. NANO LETTERS 2023; 23:4399-4405. [PMID: 37154560 DOI: 10.1021/acs.nanolett.3c00678] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Transition metal dichalcogenide heterostructures provide a versatile platform to explore electronic and excitonic phases. As the excitation density exceeds the critical Mott density, interlayer excitons are ionized into an electron-hole plasma phase. The transport of the highly non-equilibrium plasma is relevant for high-power optoelectronic devices but has not been carefully investigated previously. Here, we employ spatially resolved pump-probe microscopy to investigate the spatial-temporal dynamics of interlayer excitons and hot-plasma phase in a MoSe2/WSe2 twisted bilayer. At the excitation density of ∼1014 cm-2, well exceeding the Mott density, we find a surprisingly rapid initial expansion of hot plasma to a few microns away from the excitation source within ∼0.2 ps. Microscopic theory reveals that this rapid expansion is mainly driven by Fermi pressure and Coulomb repulsion, while the hot carrier effect has only a minor effect in the plasma phase.
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Affiliation(s)
- Junho Choi
- Department of Physics and Center for Complex Quantum Systems, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Jacob Embley
- Department of Physics and Center for Complex Quantum Systems, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Daria D Blach
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2050, United States
| | - Raül Perea-Causín
- Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden
| | - Daniel Erkensten
- Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden
| | - Dong Seob Kim
- Department of Physics and Center for Complex Quantum Systems, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Long Yuan
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2050, United States
| | - Woo Young Yoon
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Keiji Ueno
- Department of Chemistry, Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan
| | - Emanuel Tutuc
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Samuel Brem
- Department of Physics, Philipps University of Marburg, 35037 Marburg, Germany
| | - Ermin Malic
- Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden
- Department of Physics, Philipps University of Marburg, 35037 Marburg, Germany
| | - Xiaoqin Li
- Department of Physics and Center for Complex Quantum Systems, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Libai Huang
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2050, United States
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20
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Rosati R, Paradisanos I, Huang L, Gan Z, George A, Watanabe K, Taniguchi T, Lombez L, Renucci P, Turchanin A, Urbaszek B, Malic E. Interface engineering of charge-transfer excitons in 2D lateral heterostructures. Nat Commun 2023; 14:2438. [PMID: 37117167 PMCID: PMC10147613 DOI: 10.1038/s41467-023-37889-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 04/04/2023] [Indexed: 04/30/2023] Open
Abstract
The existence of bound charge transfer (CT) excitons at the interface of monolayer lateral heterojunctions has been debated in literature, but contrary to the case of interlayer excitons in vertical heterostructure their observation still has to be confirmed. Here, we present a microscopic study investigating signatures of bound CT excitons in photoluminescence spectra at the interface of hBN-encapsulated lateral MoSe2-WSe2 heterostructures. Based on a fully microscopic and material-specific theory, we reveal the many-particle processes behind the formation of CT excitons and how they can be tuned via interface- and dielectric engineering. For junction widths smaller than the Coulomb-induced Bohr radius we predict the appearance of a low-energy CT exciton. The theoretical prediction is compared with experimental low-temperature photoluminescence measurements showing emission in the bound CT excitons energy range. We show that for hBN-encapsulated heterostructures, CT excitons exhibit small binding energies of just a few tens meV and at the same time large dipole moments, making them promising materials for optoelectronic applications (benefiting from an efficient exciton dissociation and fast dipole-driven exciton propagation). Our joint theory-experiment study presents a significant step towards a microscopic understanding of optical properties of technologically promising 2D lateral heterostructures.
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Affiliation(s)
- Roberto Rosati
- Department of Physics, Philipps-Universität Marburg, Renthof 7, D-35032, Marburg, Germany.
| | - Ioannis Paradisanos
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077, Toulouse, France
| | - Libai Huang
- Department of Chemistry, Purdue University, West Lafayette, IN, USA
| | - Ziyang Gan
- Friedrich Schiller University Jena, Institute of Physical Chemistry, 07743, Jena, Germany
- Abbe Centre of Photonics, 07745, Jena, Germany
| | - Antony George
- Friedrich Schiller University Jena, Institute of Physical Chemistry, 07743, Jena, Germany
- Abbe Centre of Photonics, 07745, Jena, Germany
| | - 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
| | - Laurent Lombez
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077, Toulouse, France
| | - Pierre Renucci
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077, Toulouse, France
| | - Andrey Turchanin
- Friedrich Schiller University Jena, Institute of Physical Chemistry, 07743, Jena, Germany
- Abbe Centre of Photonics, 07745, Jena, Germany
| | - Bernhard Urbaszek
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077, Toulouse, France
- Institute of Condensed Matter Physics, Technische Universität Darmstadt, 64289, Darmstadt, Germany
| | - Ermin Malic
- Department of Physics, Philipps-Universität Marburg, Renthof 7, D-35032, Marburg, Germany
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21
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Nie X, Wu X, Wang Y, Ban S, Lei Z, Yi J, Liu Y, Liu Y. Surface acoustic wave induced phenomena in two-dimensional materials. NANOSCALE HORIZONS 2023; 8:158-175. [PMID: 36448884 DOI: 10.1039/d2nh00458e] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Surface acoustic wave (SAW)-matter interaction provides a fascinating key for inducing and manipulating novel phenomena and functionalities in two-dimensional (2D) materials. The dynamic strain field and piezo-electric field associated with propagating SAWs determine the coherent manipulation and transduction between 2D excitons and phonons. Over the past decade, many intriguing acoustic-induced effects, including the acousto-electric effect, acousto-galvanic effect, acoustic Stark effect, acoustic Hall effect and acoustic exciton transport, have been reported experimentally. However, many more phenomena, such as the valley acousto-electric effect, valley acousto-electric Hall effect and acoustic spin Hall effect, were only theoretically proposed, the experimental verification of which are yet to be achieved. In this minireview, we attempt to overview the recent breakthrough of SAW-induced phenomena covering acoustic charge transport, acoustic exciton transport and modulation, and coherent acoustic phonons. Perspectives on the opportunities of the proposed SAW-induced phenomena, as well as open experimental challenges, are also discussed, attempting to offer some guidelines for experimentalists and theorists to explore the desired exotic properties and boost practical applications of 2D materials.
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Affiliation(s)
- Xuchen Nie
- Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education, State Key Laboratory of Mechanics and Control of Mechanical Structures, and Institute for Frontier Science, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China.
| | - Xiaoyue Wu
- Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education, State Key Laboratory of Mechanics and Control of Mechanical Structures, and Institute for Frontier Science, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China.
| | - Yang Wang
- Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education, State Key Laboratory of Mechanics and Control of Mechanical Structures, and Institute for Frontier Science, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China.
| | - Siyuan Ban
- Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education, State Key Laboratory of Mechanics and Control of Mechanical Structures, and Institute for Frontier Science, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China.
| | - Zhihao Lei
- Global Innovative Centre for Advanced Nanomaterials, College of Engineering, Science and Environment, The University of Newcastle, NSW, 2308, Australia
| | - Jiabao Yi
- Global Innovative Centre for Advanced Nanomaterials, College of Engineering, Science and Environment, The University of Newcastle, NSW, 2308, Australia
| | - Ying Liu
- College of Jincheng, Nanjing University of Aeronautics and Astronautics, Nanjing 211156, China.
| | - Yanpeng Liu
- Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education, State Key Laboratory of Mechanics and Control of Mechanical Structures, and Institute for Frontier Science, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China.
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22
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Thompson JJP, Lumsargis V, Feierabend M, Zhao Q, Wang K, Dou L, Huang L, Malic E. Interlayer exciton landscape in WS 2/tetracene heterostructures. NANOSCALE 2023; 15:1730-1738. [PMID: 36594632 DOI: 10.1039/d2nr02055f] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The vertical stacking of two-dimensional materials into heterostructures gives rise to a plethora of intriguing optoelectronic properties and presents an unprecedented potential for technological development. While much progress has been made combining different monolayers of transition metal dichalcogenides (TMDs), little is known about TMD-based heterostructures including organic layers of molecules. Here, we present a joint theory-experiment study on a TMD/tetracene heterostructure demonstrating clear signatures of spatially separated interlayer excitons in low temperature photoluminescence spectra. Here, the Coulomb-bound electrons and holes are localized either in the TMD or in the molecule layer, respectively. We reveal both in theory and experiment signatures of the entire intra- and interlayer exciton landscape in the photoluminescence spectra. In particular, we find both in theory and experiment a pronounced transfer of intensity from the intralayer TMD exciton to a series of energetically lower interlayer excitons with decreasing temperature. In addition, we find signatures of phonon-sidebands stemming from these interlayer exciton states. Our findings shed light on the microscopic nature of interlayer excitons in TMD/molecule heterostructures and could have important implications for technological applications of these materials.
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Affiliation(s)
- Joshua J P Thompson
- Department of Physics, Philipps-Universität Marburg, 35037 Marburg, Germany.
| | - Victoria Lumsargis
- Department of Chemistry, Purdue University, West Lafayette, Indiana, 47907, USA
| | - Maja Feierabend
- Department of Physics, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Quichen Zhao
- Department of Chemistry, Purdue University, West Lafayette, Indiana, 47907, USA
- State Key Laboratory of Superhard Materials, Jilin University, Changchun, Jilin, 130012, China
| | - Kang Wang
- Davidson School of Chemical Engineering, Purdue University, West Lafayette, Indiana, 47907, USA
| | - Letian Dou
- Davidson School of Chemical Engineering, Purdue University, West Lafayette, Indiana, 47907, USA
| | - Libai Huang
- Department of Chemistry, Purdue University, West Lafayette, Indiana, 47907, USA
| | - Ermin Malic
- Department of Physics, Philipps-Universität Marburg, 35037 Marburg, Germany.
- Department of Physics, Chalmers University of Technology, 412 96 Gothenburg, Sweden
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23
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Hasz K, Hu Z, Park KD, Raschke MB. Tip-Enhanced Dark Exciton Nanoimaging and Local Strain Control in Monolayer WSe 2. NANO LETTERS 2023; 23:198-204. [PMID: 36538369 DOI: 10.1021/acs.nanolett.2c03959] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Dark excitons in transition-metal dichalcogenides, with their long lifetimes and strong binding energies, provide potential platforms from photonic and optoelectronic applications to quantum information science even at room temperature. However, their spatial heterogeneity and sensitivity to strain is not yet understood. Here, we combine tip-enhanced photoluminescence spectroscopy with atomic force induced strain control to nanoimage dark excitons in WSe2 and their response to local strain. Dark exciton emission is facilitated by out-of-plane picocavity Purcell enhancement giving rise to spatially highly localized emission, providing for higher spatial resolution compared to bright exciton nanoimaging. Further, tip-antenna-induced dark exciton emission is enhanced in areas of higher strain associated with bubbles. In addition, active force control shows dark exciton emission to be more sensitive to strain with both compressive and tensile lattice deformation facilitating emission. This interplay between localized strain and Purcell effects provides novel pathways for nanomechanical exciton emission control.
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Affiliation(s)
- Kathryn Hasz
- Department of Physics and JILA, University of Colorado, Boulder, Colorado 80309, United States
- Department of Physics, Carthage College, Kenosha, Wisconsin 53140, United States
| | - Zuocheng Hu
- Department of Physics and JILA, University of Colorado, Boulder, Colorado 80309, United States
| | - Kyoung-Duck Park
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
| | - Markus B Raschke
- Department of Physics and JILA, University of Colorado, Boulder, Colorado 80309, United States
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24
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Su H, Xu D, Cheng SW, Li B, Liu S, Watanabe K, Taniguchi T, Berkelbach TC, Hone JC, Delor M. Dark-Exciton Driven Energy Funneling into Dielectric Inhomogeneities in Two-Dimensional Semiconductors. NANO LETTERS 2022; 22:2843-2850. [PMID: 35294835 DOI: 10.1021/acs.nanolett.1c04997] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The optoelectronic and transport properties of two-dimensional transition metal dichalcogenide semiconductors (2D TMDs) are highly susceptible to external perturbation, enabling precise tailoring of material function through postsynthetic modifications. Here, we show that nanoscale inhomogeneities known as nanobubbles can be used for both strain and, less invasively, dielectric tuning of exciton transport in bilayer tungsten diselenide (WSe2). We use ultrasensitive spatiotemporally resolved optical scattering microscopy to directly image exciton transport, revealing that dielectric nanobubbles are surprisingly efficient at funneling and trapping excitons at room temperature, even though the energies of the bright excitons are negligibly affected. Our observations suggest that exciton funneling in dielectric inhomogeneities is driven by momentum-indirect (dark) excitons whose energies are more sensitive to dielectric perturbations than bright excitons. These results reveal a new pathway to control exciton transport in 2D semiconductors with exceptional spatial and energetic precision using dielectric engineering of dark state energetic landscapes.
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Affiliation(s)
- Haowen Su
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Ding Xu
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Shan-Wen Cheng
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Baichang Li
- Department of Mechanical Engineering, Columbia University, New York, New York 10027, United States
| | - Song Liu
- Department of Mechanical Engineering, Columbia University, New York, New York 10027, United States
| | | | | | - Timothy C Berkelbach
- Department of Chemistry, Columbia University, New York, New York 10027, United States
- Center for Computational Quantum Physics, Flatiron Institute, New York, New York 10010, United States
| | - James C Hone
- Department of Mechanical Engineering, Columbia University, New York, New York 10027, United States
| | - Milan Delor
- Department of Chemistry, Columbia University, New York, New York 10027, United States
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