1
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Rossi A, Zipfel J, Maity I, Lorenzon M, Dandu M, Barré E, Francaviglia L, Regan EC, Zhang Z, Nie JH, Barnard ES, Watanabe K, Taniguchi T, Rotenberg E, Wang F, Lischner J, Raja A, Weber-Bargioni A. Anomalous Interlayer Exciton Diffusion in WS 2/WSe 2 Moiré Heterostructure. ACS NANO 2024; 18:18202-18210. [PMID: 38950893 PMCID: PMC11256890 DOI: 10.1021/acsnano.4c00015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2024] [Revised: 05/28/2024] [Accepted: 06/05/2024] [Indexed: 07/03/2024]
Abstract
Stacking van der Waals crystals allows for the on-demand creation of a periodic potential landscape to tailor the transport of quasiparticle excitations. We investigate the diffusion of photoexcited electron-hole pairs, or excitons, at the interface of WS2/WSe2 van der Waals heterostructure over a wide range of temperatures. We observe the appearance of distinct interlayer excitons for parallel and antiparallel stacking and track their diffusion through spatially and temporally resolved photoluminescence spectroscopy from 30 to 250 K. While the measured exciton diffusivity decreases with temperature, it surprisingly plateaus below 90 K. Our observations cannot be explained by classical models like hopping in the moiré potential. A combination of ab initio theory and molecular dynamics simulations suggests that low-energy phonons arising from the mismatched lattices of moiré heterostructures, also known as phasons, play a key role in describing and understanding this anomalous behavior of exciton diffusion. Our observations indicate that the moiré potential landscape is dynamic down to very low temperatures and that the phason modes can enable efficient transport of energy in the form of excitons.
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Affiliation(s)
- Antonio Rossi
- The
Molecular Foundry, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
- Advanced
Light Source, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
- Center
for Nanotechnology Innovation @ NEST, Instituto
Italiano di Tecnologia, 56127 Pisa, Italy
| | - Jonas Zipfel
- The
Molecular Foundry, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Indrajit Maity
- Imperial
College London, South Kensington Campus, London SW7 2AZ, U.K.
| | - Monica Lorenzon
- The
Molecular Foundry, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Medha Dandu
- The
Molecular Foundry, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Elyse Barré
- The
Molecular Foundry, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Luca Francaviglia
- The
Molecular Foundry, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Emma C. Regan
- Department
of Physics, University of California at
Berkeley, Berkeley, California 94720, United States
| | - Zuocheng Zhang
- Department
of Physics, University of California at
Berkeley, Berkeley, California 94720, United States
| | - Jacob H. Nie
- Department
of Physics, University of California at
Berkeley, Berkeley, California 94720, United States
- Department
of Physics, University of California at
Santa Barbara, Santa
Barbara, California 93106, United States
| | - Edward S. Barnard
- The
Molecular Foundry, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Kenji Watanabe
- Research
Center for Functional Materials, National
Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0047, Japan
| | - Takashi Taniguchi
- International
Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0047, Japan
| | - Eli Rotenberg
- Advanced
Light Source, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Feng Wang
- Department
of Physics, University of California at
Berkeley, Berkeley, California 94720, United States
| | - Johannes Lischner
- Imperial
College London, South Kensington Campus, London SW7 2AZ, U.K.
| | - Archana Raja
- The
Molecular Foundry, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Alexander Weber-Bargioni
- The
Molecular Foundry, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
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2
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Gong Y, Yue S, Liang Y, Du W, Bian T, Jiang C, Bao X, Zhang S, Long M, Zhou G, Yin J, Deng S, Zhang Q, Wu B, Liu X. Boosting exciton mobility approaching Mott-Ioffe-Regel limit in Ruddlesden-Popper perovskites by anchoring the organic cation. Nat Commun 2024; 15:1893. [PMID: 38424438 PMCID: PMC10904778 DOI: 10.1038/s41467-024-45740-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Accepted: 02/01/2024] [Indexed: 03/02/2024] Open
Abstract
Exciton transport in two-dimensional Ruddlesden-Popper perovskite plays a pivotal role for their optoelectronic performance. However, a clear photophysical picture of exciton transport is still lacking due to strong confinement effects and intricate exciton-phonon interactions in an organic-inorganic hybrid lattice. Herein, we present a systematical study on exciton transport in (BA)2(MA)n-1PbnI3n+1 Ruddlesden-Popper perovskites using time-resolved photoluminescence microscopy. We reveal that the free exciton mobilities in exfoliated thin flakes can be improved from around 8 cm2 V-1 s-1 to 280 cm2V-1s-1 by anchoring the soft butyl ammonium cation with a polymethyl methacrylate network at the surface. The mobility of the latter is close to the theoretical limit of Mott-Ioffe-Regel criterion. Combining optical measurements and theoretical studies, it is unveiled that the polymethyl methacrylate network significantly improve the lattice rigidity resulting in the decrease of deformation potential scattering and lattice fluctuation at the surface few layers. Our work elucidates the origin of high exciton mobility in Ruddlesden-Popper perovskites and opens up avenues to regulate exciton transport in two-dimensional materials.
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Affiliation(s)
- Yiyang Gong
- South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, P.R. China
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, National Center for Nanoscience and Technology, Beijing, 100190, P.R. China
- University of Chinese Academy of Sciences, Beijing, 100049, P.R. China
| | - Shuai Yue
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, National Center for Nanoscience and Technology, Beijing, 100190, P.R. China
- University of Chinese Academy of Sciences, Beijing, 100049, P.R. China
| | - Yin Liang
- School of Materials Science and Engineering, Peking University, Beijing, 100871, P.R. China
| | - Wenna Du
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, National Center for Nanoscience and Technology, Beijing, 100190, P.R. China
- University of Chinese Academy of Sciences, Beijing, 100049, P.R. China
| | - Tieyuan Bian
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, 999077, P.R. China
| | - Chuanxiu Jiang
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, National Center for Nanoscience and Technology, Beijing, 100190, P.R. China
- University of Chinese Academy of Sciences, Beijing, 100049, P.R. China
| | - Xiaotian Bao
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, National Center for Nanoscience and Technology, Beijing, 100190, P.R. China
| | - Shuai Zhang
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, National Center for Nanoscience and Technology, Beijing, 100190, P.R. China
- University of Chinese Academy of Sciences, Beijing, 100049, P.R. China
| | - Mingzhu Long
- South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, P.R. China
| | - Guofu Zhou
- South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, P.R. China
| | - Jun Yin
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, 999077, P.R. China
| | - Shibin Deng
- Ultrafast Electron Microscopy Laboratory, School of Physics, Nankai University, Tianjin, 300071, P.R. China
- The MOE Key Laboratory of Weak-Light Nonlinear Photonics, School of Physics, Nankai University, Tianjin, 300071, P.R. China
| | - Qing Zhang
- School of Materials Science and Engineering, Peking University, Beijing, 100871, P.R. China.
| | - Bo Wu
- South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, P.R. China.
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, National Center for Nanoscience and Technology, Beijing, 100190, P.R. China.
| | - Xinfeng Liu
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, National Center for Nanoscience and Technology, Beijing, 100190, P.R. China.
- University of Chinese Academy of Sciences, Beijing, 100049, P.R. China.
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3
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Del Águila AG, Wong YR, Wadgaonkar I, Fieramosca A, Liu X, Vaklinova K, Dal Forno S, Do TTH, Wei HY, Watanabe K, Taniguchi T, Novoselov KS, Koperski M, Battiato M, Xiong Q. Ultrafast exciton fluid flow in an atomically thin MoS 2 semiconductor. NATURE NANOTECHNOLOGY 2023; 18:1012-1019. [PMID: 37524907 DOI: 10.1038/s41565-023-01438-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 06/01/2023] [Indexed: 08/02/2023]
Abstract
Excitons (coupled electron-hole pairs) in semiconductors can form collective states that sometimes exhibit spectacular nonlinear properties. Here, we show experimental evidence of a collective state of short-lived excitons in a direct-bandgap, atomically thin MoS2 semiconductor whose propagation resembles that of a classical liquid as suggested by the nearly uniform photoluminescence through the MoS2 monolayer regardless of crystallographic defects and geometric constraints. The exciton fluid flows over ultralong distances (at least 60 μm) at a speed of ~1.8 × 107 m s-1 (~6% the speed of light). The collective phase emerges above a critical laser power, in the absence of free charges and below a critical temperature (usually Tc ≈ 150 K) approaching room temperature in hexagonal-boron-nitride-encapsulated devices. Our theoretical simulations suggest that momentum is conserved and local equilibrium is achieved among excitons; both these features are compatible with a fluid dynamics description of the exciton transport.
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Affiliation(s)
- Andrés Granados Del Águila
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore.
| | - Yi Ren Wong
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore
| | - Indrajit Wadgaonkar
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore
| | - Antonio Fieramosca
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore
| | - Xue Liu
- Institutes of Physical Science and Information Technology, Anhui University, Hefei, P.R. China
| | - Kristina Vaklinova
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, Singapore
| | - Stefano Dal Forno
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore
| | - T Thu Ha Do
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), Singapore, Republic of Singapore
| | - Ho Yi Wei
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, Singapore
- Department of Physics, National University of Singapore, Singapore, Singapore
| | - K Watanabe
- National Institute for Materials Science, Tsukuba, Japan
| | - T Taniguchi
- National Institute for Materials Science, Tsukuba, Japan
| | - Kostya S Novoselov
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, Singapore
- Department of Materials Science and Engineering, National University of Singapore, Singapore, Singapore
| | - Maciej Koperski
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, Singapore
- Department of Materials Science and Engineering, National University of Singapore, Singapore, Singapore
| | - Marco Battiato
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore
| | - Qihua Xiong
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, P.R. China.
- Frontier Science Center for Quantum Information, Beijing, P.R. China.
- Collaborative Innovation Center of Quantum Matter, Beijing, P.R. China.
- Beijing Academy of Quantum Information Sciences, Beijing, P.R. China.
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4
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Wagner K, Iakovlev ZA, Ziegler JD, Cuccu M, Taniguchi T, Watanabe K, Glazov MM, Chernikov A. Diffusion of Excitons in a Two-Dimensional Fermi Sea of Free Charges. NANO LETTERS 2023. [PMID: 37220259 DOI: 10.1021/acs.nanolett.2c03796] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Propagation of light-emitting quasiparticles is of central importance across the fields of condensed matter physics and nanomaterials science. We experimentally demonstrate diffusion of excitons in the presence of a continuously tunable Fermi sea of free charge carriers in a monolayer semiconductor. Light emission from tightly bound exciton states in electrically gated WSe2 monolayer is detected using spatially and temporally resolved microscopy. The measurements reveal a nonmonotonic dependence of the exciton diffusion coefficient on the charge carrier density in both electron and hole doped regimes. Supported by analytical theory describing exciton-carrier interactions in a dissipative system, we identify distinct regimes of elastic scattering and quasiparticle formation determining exciton diffusion. The crossover region exhibits a highly unusual behavior of an increasing diffusion coefficient with increasing carrier densities. Temperature-dependent diffusion measurements further reveal characteristic signatures of freely propagating excitonic complexes dressed by free charges with effective mobilities up to 3 × 103 cm2/(V s).
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Affiliation(s)
- Koloman Wagner
- Institute of Applied Physics and Wüzburg-Dresden Cluster of Excellence ct.qmat, Technische Universität Dresden, 01062 Dresden, Germany
- Department of Physics, University of Regensburg, 93053 Regensburg, Germany
| | | | - Jonas D Ziegler
- Institute of Applied Physics and Wüzburg-Dresden Cluster of Excellence ct.qmat, Technische Universität Dresden, 01062 Dresden, Germany
- Department of Physics, University of Regensburg, 93053 Regensburg, Germany
| | - Marzia Cuccu
- Institute of Applied Physics and Wüzburg-Dresden Cluster of Excellence ct.qmat, Technische Universität Dresden, 01062 Dresden, Germany
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Ibaraki 305-004, Japan
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Ibaraki 305-004, Japan
| | | | - Alexey Chernikov
- Institute of Applied Physics and Wüzburg-Dresden Cluster of Excellence ct.qmat, Technische Universität Dresden, 01062 Dresden, Germany
- Department of Physics, University of Regensburg, 93053 Regensburg, Germany
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5
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Chen X, Reichardt S, Lin ML, Leng YC, Lu Y, Wu H, Mei R, Wirtz L, Zhang X, Ferrari AC, Tan PH. Control of Raman Scattering Quantum Interference Pathways in Graphene. ACS NANO 2023; 17:5956-5962. [PMID: 36897053 PMCID: PMC10062028 DOI: 10.1021/acsnano.3c00180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 02/24/2023] [Indexed: 06/18/2023]
Abstract
Graphene is an ideal platform to study the coherence of quantum interference pathways by tuning doping or laser excitation energy. The latter produces a Raman excitation profile that provides direct insight into the lifetimes of intermediate electronic excitations and, therefore, on quantum interference, which has so far remained elusive. Here, we control the Raman scattering pathways by tuning the laser excitation energy in graphene doped up to 1.05 eV. The Raman excitation profile of the G mode indicates its position and full width at half-maximum are linearly dependent on doping. Doping-enhanced electron-electron interactions dominate the lifetimes of Raman scattering pathways and reduce Raman interference. This will provide guidance for engineering quantum pathways for doped graphene, nanotubes, and topological insulators.
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Affiliation(s)
- Xue Chen
- State
Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- Center
of Materials Science and Optoelectronics Engineering and CAS Center
of Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Sven Reichardt
- Department
of Physics and Materials Science, University
of Luxembourg, Luxembourg 1511, Luxembourg
| | - Miao-Ling Lin
- State
Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Yu-Chen Leng
- State
Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Yan Lu
- State
Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Heng Wu
- State
Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- Center
of Materials Science and Optoelectronics Engineering and CAS Center
of Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Rui Mei
- State
Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- Center
of Materials Science and Optoelectronics Engineering and CAS Center
of Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ludger Wirtz
- Department
of Physics and Materials Science, University
of Luxembourg, Luxembourg 1511, Luxembourg
| | - Xin Zhang
- State
Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- Center
of Materials Science and Optoelectronics Engineering and CAS Center
of Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Andrea C. Ferrari
- Cambridge
Graphene Centre, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA, United Kingdom
| | - Ping-Heng Tan
- State
Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- Center
of Materials Science and Optoelectronics Engineering and CAS Center
of Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100049, China
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6
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Tan QH, Li YM, Lai JM, Sun YJ, Zhang Z, Song F, Robert C, Marie X, Gao W, Tan PH, Zhang J. Quantum interference between dark-excitons and zone-edged acoustic phonons in few-layer WS 2. Nat Commun 2023; 14:88. [PMID: 36604415 PMCID: PMC9816112 DOI: 10.1038/s41467-022-35714-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 12/15/2022] [Indexed: 01/07/2023] Open
Abstract
Fano resonance which describes a quantum interference between continuum and discrete states, provides a unique method for studying strongly interacting physics. Here, we report a Fano resonance between dark excitons and zone-edged acoustic phonons in few-layer WS2 by using the resonant Raman technique. The discrete phonons with large momentum at the M-point of the Brillouin zone and the continuum dark exciton states related to the optically forbidden transition at K and Q valleys are coupled by the exciton-phonon interactions. We observe rich Fano resonance behaviors across layers and modes defined by an asymmetry-parameter q: including constructive interference with two mirrored asymmetry Fano peaks (weak coupling, q > 1 and q < - 1), and destructive interference with Fano dip (strong coupling, ∣q∣ < < 1). Our results provide new insight into the exciton-phonon quantum interference in two-dimensional semiconductors, where such interferences play a key role in their transport, optical, and thermodynamic properties.
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Affiliation(s)
- Qing-Hai Tan
- grid.9227.e0000000119573309State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083 China ,grid.410726.60000 0004 1797 8419Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049 China ,grid.59025.3b0000 0001 2224 0361Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore, Singapore
| | - Yun-Mei Li
- grid.12955.3a0000 0001 2264 7233Department of Physics, Xiamen University, Xiamen, 361005 China
| | - Jia-Min Lai
- grid.9227.e0000000119573309State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083 China ,grid.410726.60000 0004 1797 8419Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Yu-Jia Sun
- grid.9227.e0000000119573309State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083 China ,grid.410726.60000 0004 1797 8419Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Zhe Zhang
- grid.9227.e0000000119573309State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083 China ,grid.410726.60000 0004 1797 8419Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Feilong Song
- grid.9227.e0000000119573309State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083 China ,grid.410726.60000 0004 1797 8419Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Cedric Robert
- grid.462768.90000 0004 0383 4043University of Toulouse, INSA-CNRS-UPS, LPCNO, 135 Av. Rangueil, 31077 Toulouse, France
| | - Xavier Marie
- grid.462768.90000 0004 0383 4043University of Toulouse, INSA-CNRS-UPS, LPCNO, 135 Av. Rangueil, 31077 Toulouse, France
| | - Weibo Gao
- grid.59025.3b0000 0001 2224 0361Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore, Singapore ,grid.59025.3b0000 0001 2224 0361The Photonics Institute and Centre for Disruptive Photonic Technologies, Nanyang Technological University, 637371 Singapore, Singapore ,grid.4280.e0000 0001 2180 6431Centre for Quantum Technologies, National University of Singapore, Singapore, 117543 Singapore
| | - Ping-Heng Tan
- grid.9227.e0000000119573309State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083 China ,grid.410726.60000 0004 1797 8419Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Jun Zhang
- grid.9227.e0000000119573309State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083 China ,grid.410726.60000 0004 1797 8419Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049 China ,grid.410726.60000 0004 1797 8419CAS Center of Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing, 100049 China
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7
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Relaxation and Transport of Excitonic Polaron in Monolayer Transition Metal Dichalcogenides. IRANIAN JOURNAL OF SCIENCE AND TECHNOLOGY, TRANSACTIONS A: SCIENCE 2022. [DOI: 10.1007/s40995-022-01283-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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8
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Wagner K, Zipfel J, Rosati R, Wietek E, Ziegler JD, Brem S, Perea-Causín R, Taniguchi T, Watanabe K, Glazov MM, Malic E, Chernikov A. Nonclassical Exciton Diffusion in Monolayer WSe_{2}. PHYSICAL REVIEW LETTERS 2021; 127:076801. [PMID: 34459627 DOI: 10.1103/physrevlett.127.076801] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 06/24/2021] [Indexed: 06/13/2023]
Abstract
We experimentally demonstrate time-resolved exciton propagation in a monolayer semiconductor at cryogenic temperatures. Monitoring phonon-assisted recombination of dark states, we find a highly unusual case of exciton diffusion. While at 5 K the diffusivity is intrinsically limited by acoustic phonon scattering, we observe a pronounced decrease of the diffusion coefficient with increasing temperature, far below the activation threshold of higher-energy phonon modes. This behavior corresponds neither to well-known regimes of semiclassical free-particle transport nor to the thermally activated hopping in systems with strong localization. Its origin is discussed in the framework of both microscopic numerical and semiphenomenological analytical models illustrating the observed characteristics of nonclassical propagation. Challenging the established description of mobile excitons in monolayer semiconductors, these results open up avenues to study quantum transport phenomena for excitonic quasiparticles in atomically thin van der Waals materials and their heterostructures.
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Affiliation(s)
- Koloman Wagner
- Department of Physics, University of Regensburg, Regensburg D-93053, Germany
| | - Jonas Zipfel
- Department of Physics, University of Regensburg, Regensburg D-93053, Germany
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Roberto Rosati
- Department of Physics, Philipps-Universität Marburg, Renthof 7, Marburg D-35032, Germany
| | - Edith Wietek
- Department of Physics, University of Regensburg, Regensburg D-93053, Germany
| | - Jonas D Ziegler
- Department of Physics, University of Regensburg, Regensburg D-93053, Germany
| | - Samuel Brem
- Department of Physics, Philipps-Universität Marburg, Renthof 7, Marburg D-35032, Germany
| | - Raül Perea-Causín
- Department of Physics, Chalmers University of Technology, Fysikgården 1, 41258 Gothenburg, Sweden
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Ibaraki 305-004, Japan
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Ibaraki 305-004, Japan
| | | | - Ermin Malic
- Department of Physics, Philipps-Universität Marburg, Renthof 7, Marburg D-35032, Germany
- Department of Physics, Chalmers University of Technology, Fysikgården 1, 41258 Gothenburg, Sweden
| | - Alexey Chernikov
- Department of Physics, University of Regensburg, Regensburg D-93053, Germany
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Würzburg-Dresden Cluster of Excellence ct.qmat, Technische Universität Dresden, 01062 Dresden, Germany
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9
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Li Z, Lu X, Cordovilla Leon DF, Lyu Z, Xie H, Hou J, Lu Y, Guo X, Kaczmarek A, Taniguchi T, Watanabe K, Zhao L, Yang L, Deotare PB. Interlayer Exciton Transport in MoSe 2/WSe 2 Heterostructures. ACS NANO 2021; 15:1539-1547. [PMID: 33417424 DOI: 10.1021/acsnano.0c08981] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
A moiré superlattice formed by stacking two lattice mismatched transition metal dichalcogenide monolayers, functions as a diffusion barrier that affects the energy transport and dynamics of interlayer excitons (electron and hole spatially concentrated in different monolayers). In this work, we experimentally quantify the diffusion barrier experienced by interlayer excitons in hexagonal boron nitride-encapsulated molybdenum diselenide/tungsten diselenide (MoSe2/WSe2) heterostructures with different twist angles. We observe the localization of interlayer excitons at low temperature and the temperature-activated diffusivity as a function of twist angle and hence attribute it to the deep periodic potentials arising from the moiré superlattice. We further support the observations with theoretical calculations, Monte Carlo simulations, and a three-level model that represents the exciton dynamics at various temperatures.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Ibaraki 305-0044, Japan
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
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10
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Paradisanos I, Wang G, Alexeev EM, Cadore AR, Marie X, Ferrari AC, Glazov MM, Urbaszek B. Efficient phonon cascades in WSe 2 monolayers. Nat Commun 2021; 12:538. [PMID: 33483475 PMCID: PMC7822848 DOI: 10.1038/s41467-020-20244-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 11/10/2020] [Indexed: 01/30/2023] Open
Abstract
Energy relaxation of photo-excited charge carriers is of significant fundamental interest and crucial for the performance of monolayer transition metal dichalcogenides in optoelectronics. The primary stages of carrier relaxation affect a plethora of subsequent physical mechanisms. Here we measure light scattering and emission in tungsten diselenide monolayers close to the laser excitation energy (down to ~0.6 meV). We reveal a series of periodic maxima in the hot photoluminescence intensity, stemming from energy states higher than the A-exciton state. We find a period ~15 meV for 7 peaks below (Stokes) and 5 peaks above (anti-Stokes) the laser excitation energy, with a strong temperature dependence. These are assigned to phonon cascades, whereby carriers undergo phonon-induced transitions between real states above the free-carrier gap with a probability of radiative recombination at each step. We infer that intermediate states in the conduction band at the Λ-valley of the Brillouin zone participate in the cascade process of tungsten diselenide monolayers. This provides a fundamental understanding of the first stages of carrier-phonon interaction, useful for optoelectronic applications of layered semiconductors.
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Affiliation(s)
- Ioannis Paradisanos
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, Toulouse, 31077, France.
- Cambridge Graphene Centre, University of Cambridge, Cambridge, CB3 0FA, UK.
| | - Gang Wang
- Cambridge Graphene Centre, University of Cambridge, Cambridge, CB3 0FA, UK
- Key Lab of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, 100081, China
| | - Evgeny M Alexeev
- Cambridge Graphene Centre, University of Cambridge, Cambridge, CB3 0FA, UK
| | - Alisson R Cadore
- Cambridge Graphene Centre, University of Cambridge, Cambridge, CB3 0FA, UK
| | - Xavier Marie
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, Toulouse, 31077, France
| | - Andrea C Ferrari
- Cambridge Graphene Centre, University of Cambridge, Cambridge, CB3 0FA, UK.
| | | | - Bernhard Urbaszek
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, Toulouse, 31077, France.
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11
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Glazov MM, Golub LE. Skew Scattering and Side Jump Drive Exciton Valley Hall Effect in Two-Dimensional Crystals. PHYSICAL REVIEW LETTERS 2020; 125:157403. [PMID: 33095628 DOI: 10.1103/physrevlett.125.157403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 09/03/2020] [Indexed: 06/11/2023]
Abstract
Exciton valley Hall effect is the spatial separation of the valley-tagged excitons by a drag force. Usually, the effect is associated with the anomalous velocity acquired by the particles due to the Berry curvature of the Bloch bands. Here we show that the anomalous velocity plays no role in the exciton valley Hall effect, which is governed by the side-jump and skew scattering. We develop a microscopic theory of the exciton valley Hall effect in the presence of a synthetic electric field and phonon drag and calculate all relevant contributions to the valley Hall current also demonstrating the cancellation of the anomalous velocity. The sensitivity of the effect to the origin of the drag force and to the scattering processes is shown. We extend the drift-diffusion model to account for the valley Hall effect and calculate the exciton density and valley polarization profiles.
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Affiliation(s)
- M M Glazov
- Ioffe Institute, 194021 St. Petersburg, Russia
| | - L E Golub
- Ioffe Institute, 194021 St. Petersburg, Russia
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12
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Ziegler JD, Zipfel J, Meisinger B, Menahem M, Zhu X, Taniguchi T, Watanabe K, Yaffe O, Egger DA, Chernikov A. Fast and Anomalous Exciton Diffusion in Two-Dimensional Hybrid Perovskites. NANO LETTERS 2020; 20:6674-6681. [PMID: 32786939 DOI: 10.1021/acs.nanolett.0c02472] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Two-dimensional hybrid perovskites are currently in the spotlight of condensed matter and nanotechnology research due to their intriguing optoelectronic and vibrational properties with emerging potential for light-harvesting and light-emitting applications. While it is known that these natural quantum wells host tightly bound excitons, the mobilities of these fundamental optical excitations at the heart of the optoelectronic applications are barely explored. Here, we directly monitor the diffusion of excitons through ultrafast emission microscopy from liquid helium to room temperature in hBN-encapsulated two-dimensional hybrid perovskites. We find very fast diffusion with characteristic hallmarks of free exciton propagation for all temperatures above 50 K. In the cryogenic regime, we observe nonlinear, anomalous behavior with an exceptionally rapid expansion of the exciton cloud followed by a very slow and even negative effective diffusion. We discuss our findings in view of efficient exciton-phonon coupling, highlighting two-dimensional hybrids as promising platforms for basic research and optoelectronic applications.
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Affiliation(s)
- Jonas D Ziegler
- Department of Physics, University of Regensburg, Regensburg D-93053, Germany
| | - Jonas Zipfel
- Department of Physics, University of Regensburg, Regensburg D-93053, Germany
| | - Barbara Meisinger
- Department of Physics, University of Regensburg, Regensburg D-93053, Germany
| | - Matan Menahem
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Xiangzhou Zhu
- Department of Physics, Technical University of Munich, 85748 Garching, Germany
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Ibaraki 305-004, Japan
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Ibaraki 305-004, Japan
| | - Omer Yaffe
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel
| | - David A Egger
- Department of Physics, Technical University of Munich, 85748 Garching, Germany
| | - Alexey Chernikov
- Department of Physics, University of Regensburg, Regensburg D-93053, Germany
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