1
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Rahaman M, Marino E, Joly AG, Stevens CE, Song S, Alfieri A, Jiang Z, O'Callahan BT, Rosen DJ, Jo K, Kim G, Hendrickson JR, El-Khoury PZ, Murray C, Jariwala D. Tunable Localized Charge Transfer Excitons in Nanoplatelet-2D Chalcogenide van der Waals Heterostructures. ACS NANO 2024; 18:15185-15193. [PMID: 38809690 DOI: 10.1021/acsnano.4c03260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2024]
Abstract
Observation of interlayer, charge transfer (CT) excitons in van der Waals heterostructures (vdWHs) based on 2D-2D systems has been well investigated. While conceptually interesting, these charge transfer excitons are highly delocalized and spatially localizing them requires twisting layers at very specific angles. This issue of localizing the CT excitons can be overcome via making nanoplate-2D material heterostructures (N2DHs) where one of the components is a spatially quantum confined medium. Here, we demonstrate the formation of CT excitons in a mixed dimensional system comprising MoSe2 and WSe2 monolayers and CdSe/CdS-based core/shell nanoplates (NPLs). Spectral signatures of CT excitons in our N2DHs were resolved locally at the 2D/single-NPL heterointerface using tip-enhanced photoluminescence (TEPL) at room temperature. By varying both the 2D material and the shell thickness of the NPLs and applying an out-of-plane electric field, the exciton resonance energy was tuned by up to 100 meV. Our finding is a significant step toward the realization of highly tunable N2DH-based next-generation photonic devices.
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Affiliation(s)
- Mahfujur Rahaman
- Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Emanuele Marino
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Dipartimento di Fisica e Chimica, Università degli Studi di Palermo, Via Archirafi 36, 90123 Palermo, Italy
| | - Alan G Joly
- Physical and Chemical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Christopher E Stevens
- Sensors Directorate, Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433, United States
- KBR Inc., Beavercreek, Ohio 45431, United States
| | - Seunguk Song
- Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Adam Alfieri
- Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Zhiqiao Jiang
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Brian T O'Callahan
- Physical and Chemical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Daniel J Rosen
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Kiyoung Jo
- Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Gwangwoo Kim
- Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Joshua R Hendrickson
- Sensors Directorate, Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433, United States
| | - Patrick Z El-Khoury
- Physical and Chemical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Christopher Murray
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Deep Jariwala
- Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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2
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Verma N, Guerci D, Queiroz R. Geometric Stiffness in Interlayer Exciton Condensates. PHYSICAL REVIEW LETTERS 2024; 132:236001. [PMID: 38905692 DOI: 10.1103/physrevlett.132.236001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 03/28/2024] [Accepted: 05/06/2024] [Indexed: 06/23/2024]
Abstract
Recent experiments have confirmed the presence of interlayer excitons in the ground state of transition metal dichalcogenide bilayers. The interlayer excitons are expected to show remarkable transport properties when they undergo Bose condensation. In this Letter, we demonstrate that quantum geometry of Bloch wave functions plays an important role in the phase stiffness of the interlayer exciton condensate. Notably, we identify a geometric contribution that amplifies the stiffness, leading to the formation of a robust condensate with an increased Berezinskii-Kosterlitz-Thouless temperature. Our results have direct implications for the ongoing experimental efforts on interlayer excitons in materials that have nontrivial quantum geometry. We provide estimates for the geometric contribution in transition metal dichalcogenide bilayers through a realistic continuum model with gated Coulomb interaction, and find that the substantially increased stiffness may allow an interlayer exciton condensate to be realized at amenable experimental conditions.
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3
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Zhang L, Gu L, Ni R, Xie M, Park S, Jang H, Ma R, Taniguchi T, Watanabe K, Zhou Y. Electrical Control and Transport of Tightly Bound Interlayer Excitons in a MoSe_{2}/hBN/MoSe_{2} Heterostructure. PHYSICAL REVIEW LETTERS 2024; 132:216903. [PMID: 38856288 DOI: 10.1103/physrevlett.132.216903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 03/11/2024] [Accepted: 04/15/2024] [Indexed: 06/11/2024]
Abstract
Controlling interlayer excitons in Van der Waals heterostructures holds promise for exploring Bose-Einstein condensates and developing novel optoelectronic applications, such as excitonic integrated circuits. Despite intensive studies, several key fundamental properties of interlayer excitons, such as their binding energies and interactions with charges, remain not well understood. Here we report the formation of momentum-direct interlayer excitons in a high-quality MoSe_{2}/hBN/MoSe_{2} heterostructure under an electric field, characterized by bright photoluminescence (PL) emission with high quantum yield and a narrow linewidth of less than 4 meV. These interlayer excitons show electrically tunable emission energy spanning ∼180 meV through the Stark effect, and exhibit a sizable binding energy of ∼81 meV in the intrinsic regime, along with trion binding energies of a few millielectronvolts. Remarkably, we demonstrate the long-range transport of interlayer excitons with a characteristic diffusion length exceeding 10 μm, which can be attributed, in part, to their dipolar repulsive interactions. Spatially and polarization-resolved spectroscopic studies reveal rich exciton physics in the system, such as valley polarization, local trapping, and the possible existence of dark interlayer excitons. The formation and transport of tightly bound interlayer excitons with narrow linewidth, coupled with the ability to electrically manipulate their properties, open exciting new avenues for exploring quantum many-body physics, including excitonic condensate and superfluidity, and for developing novel optoelectronic devices, such as exciton and photon routers.
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Affiliation(s)
- Lifu Zhang
- Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA
| | - Liuxin Gu
- Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA
| | - Ruihao Ni
- Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA
| | - Ming Xie
- Condensed Matter Theory Center, University of Maryland, College Park, Maryland 20742, USA
| | - Suji Park
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Houk Jang
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Rundong Ma
- Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA
| | - Takashi Taniguchi
- Research Center for Electronic and Optical Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Kenji Watanabe
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - You Zhou
- Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA
- Maryland Quantum Materials Center, College Park, Maryland 20742, USA
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4
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Feng S, Campbell AJ, Brotons-Gisbert M, Andres-Penares D, Baek H, Taniguchi T, Watanabe K, Urbaszek B, Gerber IC, Gerardot BD. Highly tunable ground and excited state excitonic dipoles in multilayer 2H-MoSe 2. Nat Commun 2024; 15:4377. [PMID: 38782967 DOI: 10.1038/s41467-024-48476-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Accepted: 04/29/2024] [Indexed: 05/25/2024] Open
Abstract
The fundamental properties of an exciton are determined by the spin, valley, energy, and spatial wavefunctions of the Coulomb-bound electron and hole. In van der Waals materials, these attributes can be widely engineered through layer stacking configuration to create highly tunable interlayer excitons with static out-of-plane electric dipoles, at the expense of the strength of the oscillating in-plane dipole responsible for light-matter coupling. Here we show that interlayer excitons in bi- and tri-layer 2H-MoSe2 crystals exhibit electric-field-driven coupling with the ground (1s) and excited states (2s) of the intralayer A excitons. We demonstrate that the hybrid states of these distinct exciton species provide strong oscillator strength, large permanent dipoles (up to 0.73 ± 0.01 enm), high energy tunability (up to ~200 meV), and full control of the spin and valley characteristics such that the exciton g-factor can be manipulated over a large range (from -4 to +14). Further, we observe the bi- and tri-layer excited state (2s) interlayer excitons and their coupling with the intralayer excitons states (1s and 2s). Our results, in good agreement with a coupled oscillator model with spin (layer)-selectivity and beyond standard density functional theory calculations, promote multilayer 2H-MoSe2 as a highly tunable platform to explore exciton-exciton interactions with strong light-matter interactions.
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Affiliation(s)
- Shun Feng
- Institute of Photonics and Quantum Sciences, SUPA, Heriot-Watt University, Edinburgh, UK
| | - Aidan J Campbell
- Institute of Photonics and Quantum Sciences, SUPA, Heriot-Watt University, Edinburgh, UK
| | - Mauro Brotons-Gisbert
- Institute of Photonics and Quantum Sciences, SUPA, Heriot-Watt University, Edinburgh, UK.
| | - Daniel Andres-Penares
- Institute of Photonics and Quantum Sciences, SUPA, Heriot-Watt University, Edinburgh, UK
| | - Hyeonjun Baek
- Institute of Photonics and Quantum Sciences, SUPA, Heriot-Watt University, Edinburgh, UK
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
| | - Bernhard Urbaszek
- Institute of Condensed Matter Physics, Technische Universität Darmstadt, Darmstadt, Germany
| | - Iann C Gerber
- INSA-CNRS-UPS LPCNO, Université de Toulouse, Toulouse, France
| | - Brian D Gerardot
- Institute of Photonics and Quantum Sciences, SUPA, Heriot-Watt University, Edinburgh, UK.
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5
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Zhao M, Wang Z, Liu L, Wang C, Liu CY, Yang F, Wu H, Gao C. Atomic-scale visualization of the interlayer Rydberg exciton complex in moiré heterostructures. Nat Commun 2024; 15:3414. [PMID: 38649358 PMCID: PMC11035671 DOI: 10.1038/s41467-024-47770-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: 08/08/2023] [Accepted: 04/10/2024] [Indexed: 04/25/2024] Open
Abstract
Excitonic systems, facilitated by optical pumping, electrostatic gating or magnetic field, sustain composite particles with fascinating physics. Although various intriguing excitonic phases have been revealed via global measurements, the atomic-scale accessibility towards excitons has yet to be established. Here, we realize the ground-state interlayer exciton complexes through the intrinsic charge transfer in monolayer YbCl3/graphite heterostructure. Combining scanning tunneling microscope and theoretical calculations, the excitonic in-gap states are directly profiled. The out-of-plane excitonic charge clouds exhibit oscillating Rydberg nodal structure, while their in-plane arrangements are determined by moiré periodicity. Exploiting the tunneling probe to reflect the shape of charge clouds, we reveal the principal quantum number hierarchy of Rydberg series, which points to an excitonic energy-level configuration with unusually large binding energy. Our results demonstrate the feasibility of mapping out the charge clouds of excitons microscopically and pave a brand-new way to directly investigate the nanoscale order of exotic correlated phases.
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Affiliation(s)
- Meng Zhao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200438, China
- Shanghai Qi Zhi Institute, Shanghai, 200232, China
| | - Zhongjie Wang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200438, China.
- Shanghai Qi Zhi Institute, Shanghai, 200232, China.
| | - Lu Liu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200438, China
- Shanghai Qi Zhi Institute, Shanghai, 200232, China
- Laboratory for Computational Physical Sciences (MOE), Fudan University, Shanghai, 200438, China
| | - Chunzheng Wang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200438, China
- Shanghai Qi Zhi Institute, Shanghai, 200232, China
| | - Cheng-Yen Liu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200438, China
- Shanghai Qi Zhi Institute, Shanghai, 200232, China
| | - Fang Yang
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Songhu Rd. 2005, Shanghai, 200438, China
- Zhangjiang Fudan International Innovation Center, Fudan University, Shanghai, 201210, China
| | - Hua Wu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200438, China.
- Shanghai Qi Zhi Institute, Shanghai, 200232, China.
- Laboratory for Computational Physical Sciences (MOE), Fudan University, Shanghai, 200438, China.
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China.
| | - Chunlei Gao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200438, China.
- Shanghai Qi Zhi Institute, Shanghai, 200232, China.
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Songhu Rd. 2005, Shanghai, 200438, China.
- Zhangjiang Fudan International Innovation Center, Fudan University, Shanghai, 201210, China.
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China.
- Shanghai Research Center for Quantum Sciences, Shanghai, 201315, China.
- Shanghai Branch, Hefei National Laboratory, Shanghai, 201315, China.
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6
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García Jomaso YA, Vargas B, Domínguez DL, Armenta-Rico RJ, Sauceda HE, Ordoñez-Romero CL, Lara-García HA, Camacho-Guardian A, Pirruccio G. Intercavity polariton slows down dynamics in strongly coupled cavities. Nat Commun 2024; 15:2915. [PMID: 38575645 PMCID: PMC10994920 DOI: 10.1038/s41467-024-47336-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: 08/31/2023] [Accepted: 03/27/2024] [Indexed: 04/06/2024] Open
Abstract
Band engineering stands as an efficient route to induce strongly correlated quantum many-body phenomena. Besides inspiring analogies among diverse physical fields, tuning on demand the group velocity is highly attractive in photonics because it allows unconventional flows of light. Λ-schemes offer a route to control the propagation of light in a lattice-free configurations, enabling exotic phases such as slow-light and allowing for highly optical non-linear systems. Here, we realize room-temperature intercavity Frenkel polaritons excited across two strongly coupled cavities. We demonstrate the formation of a tuneable heavy-polariton, akin to slow light, appearing in the absence of a periodic in-plane potential. Our photonic architecture based on a simple three-level scheme enables the unique spatial segregation of photons and excitons in different cavities and maintains a balanced degree of mixing between them. This unveils a dynamical competition between many-body scattering processes and the underlying polariton nature which leads to an increased fluorescence lifetime. The intercavity polariton features are further revealed under appropriate resonant pumping, where we observe suppression of the polariton fluorescence intensity.
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Affiliation(s)
- Yesenia A García Jomaso
- Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20-364, Ciudad de México, C.P., 01000, Mexico
| | - Brenda Vargas
- Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20-364, Ciudad de México, C.P., 01000, Mexico
| | - David Ley Domínguez
- Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20-364, Ciudad de México, C.P., 01000, Mexico
| | - Román J Armenta-Rico
- Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20-364, Ciudad de México, C.P., 01000, Mexico
| | - Huziel E Sauceda
- Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20-364, Ciudad de México, C.P., 01000, Mexico
| | - César L Ordoñez-Romero
- Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20-364, Ciudad de México, C.P., 01000, Mexico
| | - Hugo A Lara-García
- Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20-364, Ciudad de México, C.P., 01000, Mexico
| | - Arturo Camacho-Guardian
- Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20-364, Ciudad de México, C.P., 01000, Mexico.
| | - Giuseppe Pirruccio
- Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20-364, Ciudad de México, C.P., 01000, Mexico.
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7
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Shin JC, Jeong JH, Kwon J, Kim YH, Kim B, Woo SJ, Woo KY, Cho M, Watanabe K, Taniguchi T, Kim YD, Cho YH, Lee TW, Hone J, Lee CH, Lee GH. Electrically Confined Electroluminescence of Neutral Excitons in WSe 2 Light-Emitting Transistors. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2310498. [PMID: 38169481 DOI: 10.1002/adma.202310498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 12/29/2023] [Indexed: 01/05/2024]
Abstract
Monolayer transition metal dichalcogenides (TMDs) have drawn significant attention for their potential in optoelectronic applications due to their direct band gap and exceptional quantum yield. However, TMD-based light-emitting devices have shown low external quantum efficiencies as imbalanced free carrier injection often leads to the formation of non-radiative charged excitons, limiting practical applications. Here, electrically confined electroluminescence (EL) of neutral excitons in tungsten diselenide (WSe2) light-emitting transistors (LETs) based on the van der Waals heterostructure is demonstrated. The WSe2 channel is locally doped to simultaneously inject electrons and holes to the 1D region by a local graphene gate. At balanced concentrations of injected electrons and holes, the WSe2 LETs exhibit strong EL with a high external quantum efficiency (EQE) of ≈8.2 % at room temperature. These experimental and theoretical results consistently show that the enhanced EQE could be attributed to dominant exciton emission confined at the 1D region while expelling charged excitons from the active area by precise control of external electric fields. This work shows a promising approach to enhancing the EQE of 2D light-emitting transistors and modulating the recombination of exciton complexes for excitonic devices.
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Affiliation(s)
- June-Chul Shin
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - Jae Hwan Jeong
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - Junyoung Kwon
- Department of Material Science and Engineering, Yonsei University, Seoul, 03722, Republic of Korea
| | - Yeon Ho Kim
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, 02841, Republic of Korea
| | - Bumho Kim
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Seung-Je Woo
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - Kie Young Woo
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea
| | - Minhyun Cho
- Department of Physics and Department of Information Display, Kyung Hee University, Seoul, 02447, 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
| | - Young Duck Kim
- Department of Physics and Department of Information Display, Kyung Hee University, Seoul, 02447, Republic of Korea
| | - Yong-Hoon Cho
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea
| | - Tae-Woo Lee
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - James Hone
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - Chul-Ho Lee
- Department of Electrical and Computer Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - Gwan-Hyoung Lee
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
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8
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Cai CS, Lai WY, Liu PH, Chou TC, Liu RY, Lin CM, Gwo S, Hsu WT. Ultralow Auger-Assisted Interlayer Exciton Annihilation in WS 2/WSe 2 Moiré Heterobilayers. NANO LETTERS 2024; 24:2773-2781. [PMID: 38285707 PMCID: PMC10921466 DOI: 10.1021/acs.nanolett.3c04688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 01/22/2024] [Accepted: 01/23/2024] [Indexed: 01/31/2024]
Abstract
Transition metal dichalcogenide (TMD) heterobilayers have emerged as a promising platform for exploring solid-state quantum simulators and many-body quantum phenomena. Their type II band alignment, combined with the moiré superlattice, inevitably leads to nontrivial exciton interactions and dynamics. Here, we unveil the distinct Auger annihilation processes for delocalized interlayer excitons in WS2/WSe2 moiré heterobilayers. By fitting the characteristic efficiency droop and bimolecular recombination rate, we quantitatively determine an ultralow Auger coefficient of 1.3 × 10-5 cm2 s-1, which is >100-fold smaller than that of excitons in TMD monolayers. In addition, we reveal selective exciton upconversion into the WSe2 layer, which highlights the significance of intralayer electron Coulomb interactions in dictating the microscopic scattering pathways. The distinct Auger processes arising from spatial electron-hole separation have important implications for TMD heterobilayers while endowing interlayer excitons and their strongly correlated states with unique layer degrees of freedom.
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Affiliation(s)
- Cheng-Syuan Cai
- Department
of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
- National
Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Wei-Yan Lai
- Department
of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Po-Hsuan Liu
- Department
of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Tzu-Chieh Chou
- Department
of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
- National
Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Ro-Ya Liu
- National
Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Chih-Ming Lin
- Department
of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Shangjr Gwo
- Department
of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Wei-Ting Hsu
- Department
of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
- National
Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
- Research
Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan
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9
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Bange JP, Schmitt D, Bennecke W, Meneghini G, AlMutairi A, Watanabe K, Taniguchi T, Steil D, Steil S, Weitz RT, Jansen GSM, Hofmann S, Brem S, Malic E, Reutzel M, Mathias S. Probing electron-hole Coulomb correlations in the exciton landscape of a twisted semiconductor heterostructure. SCIENCE ADVANCES 2024; 10:eadi1323. [PMID: 38324690 PMCID: PMC10849592 DOI: 10.1126/sciadv.adi1323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 01/10/2024] [Indexed: 02/09/2024]
Abstract
In two-dimensional semiconductors, cooperative and correlated interactions determine the material's excitonic properties and can even lead to the creation of correlated states of matter. Here, we study the fundamental two-particle correlated exciton state formed by the Coulomb interaction between single-particle holes and electrons. We find that the ultrafast transfer of an exciton's hole across a type II band-aligned semiconductor heterostructure leads to an unexpected sub-200-femtosecond upshift of the single-particle energy of the electron being photoemitted from the two-particle exciton state. While energy relaxation usually leads to an energetic downshift of the spectroscopic signature, we show that this upshift is a clear fingerprint of the correlated interaction of the electron and hole parts of the exciton. In this way, time-resolved photoelectron spectroscopy is straightforwardly established as a powerful method to access electron-hole correlations and cooperative behavior in quantum materials. Our work highlights this capability and motivates the future study of optically inaccessible correlated excitonic and electronic states of matter.
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Affiliation(s)
- Jan Philipp Bange
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - David Schmitt
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Wiebke Bennecke
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Giuseppe Meneghini
- Fachbereich Physik, Philipps-Universität Marburg, 35032 Marburg, 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
| | - Daniel Steil
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Sabine Steil
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - R. Thomas Weitz
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
- International Center for Advanced Studies of Energy Conversion (ICASEC), University of Göttingen, Göttingen, Germany
| | - G. S. Matthijs Jansen
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Stephan Hofmann
- Department of Engineering, University of Cambridge, Cambridge CB3 0FA, UK
| | - Samuel Brem
- Fachbereich Physik, Philipps-Universität Marburg, 35032 Marburg, Germany
| | - Ermin Malic
- Fachbereich Physik, Philipps-Universität Marburg, 35032 Marburg, Germany
- Department of Physics, Chalmers University of Technology, Gothenburg, Sweden
| | - Marcel Reutzel
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Stefan Mathias
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
- International Center for Advanced Studies of Energy Conversion (ICASEC), University of Göttingen, Göttingen, Germany
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10
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Blundo E, Tuzi F, Cianci S, Cuccu M, Olkowska-Pucko K, Kipczak Ł, Contestabile G, Miriametro A, Felici M, Pettinari G, Taniguchi T, Watanabe K, Babiński A, Molas MR, Polimeni A. Localisation-to-delocalisation transition of moiré excitons in WSe 2/MoSe 2 heterostructures. Nat Commun 2024; 15:1057. [PMID: 38316753 PMCID: PMC10844653 DOI: 10.1038/s41467-024-44739-9] [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: 04/24/2023] [Accepted: 01/02/2024] [Indexed: 02/07/2024] Open
Abstract
Moiré excitons (MXs) are electron-hole pairs localised by the periodic (moiré) potential forming in two-dimensional heterostructures (HSs). MXs can be exploited, e.g., for creating nanoscale-ordered quantum emitters and achieving or probing strongly correlated electronic phases at relatively high temperatures. Here, we studied the exciton properties of WSe2/MoSe2 HSs from T = 6 K to room temperature using time-resolved and continuous-wave micro-photoluminescence also under a magnetic field. The exciton dynamics and emission lineshape evolution with temperature show clear signatures that MXs de-trap from the moiré potential and turn into free interlayer excitons (IXs) for temperatures above 100 K. The MX-to-IX transition is also apparent from the exciton magnetic moment reversing its sign when the moiré potential is not capable of localising excitons at elevated temperatures. Concomitantly, the exciton formation and decay times reduce drastically. Thus, our findings establish the conditions for a truly confined nature of the exciton states in a moiré superlattice with increasing temperature and photo-generated carrier density.
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Affiliation(s)
- Elena Blundo
- Physics Department, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy.
| | - Federico Tuzi
- Physics Department, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy
| | - Salvatore Cianci
- Physics Department, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy
| | - Marzia Cuccu
- Physics Department, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy
| | - Katarzyna Olkowska-Pucko
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093, Warsaw, Poland
| | - Łucja Kipczak
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093, Warsaw, Poland
| | - Giorgio Contestabile
- Physics Department, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy
| | - Antonio Miriametro
- Physics Department, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy
| | - Marco Felici
- Physics Department, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy
| | - Giorgio Pettinari
- Institute for Photonics and Nanotechnologies, National Research Council, 00133, Rome, Italy
| | - 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
| | - Adam Babiński
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093, Warsaw, Poland
| | - Maciej R Molas
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093, Warsaw, Poland
| | - Antonio Polimeni
- Physics Department, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy.
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11
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Handa T, Holbrook M, Olsen N, Holtzman LN, Huber L, Wang HI, Bonn M, Barmak K, Hone JC, Pasupathy AN, Zhu X. Spontaneous exciton dissociation in transition metal dichalcogenide monolayers. SCIENCE ADVANCES 2024; 10:eadj4060. [PMID: 38295176 PMCID: PMC10830119 DOI: 10.1126/sciadv.adj4060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Accepted: 12/28/2023] [Indexed: 02/02/2024]
Abstract
Since the seminal work on MoS2, photoexcitation in atomically thin transition metal dichalcogenides (TMDCs) has been assumed to result in excitons, with binding energies order of magnitude larger than thermal energy at room temperature. Here, we reexamine this foundational assumption and show that photoexcitation of TMDC monolayers can result in a substantial population of free charges. Performing ultrafast terahertz spectroscopy on large-area, single-crystal TMDC monolayers, we find that up to ~10% of excitons spontaneously dissociate into charge carriers with lifetimes exceeding 0.2 ns. Scanning tunneling microscopy reveals that photocarrier generation is intimately related to mid-gap defects, likely via trap-mediated Auger scattering. Only in state-of-the-art quality monolayers, with mid-gap trap densities as low as 109 cm-2, does intrinsic exciton physics start to dominate the terahertz response. Our findings reveal the necessity of knowing the defect density in understanding photophysics of TMDCs.
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Affiliation(s)
- Taketo Handa
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Madisen Holbrook
- Department of Physics, Columbia University, New York, NY 10027, USA
| | - Nicholas Olsen
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Luke N. Holtzman
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY 10027, USA
| | - Lucas Huber
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Hai I. Wang
- Max Planck Institute for Polymer Research, Mainz 55128, Germany
| | - Mischa Bonn
- Max Planck Institute for Polymer Research, Mainz 55128, Germany
| | - Katayun Barmak
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY 10027, USA
| | - James C. Hone
- Department of Mechanical Engineering, Columbia University, New York, NY 10027, USA
| | | | - Xiaoyang Zhu
- Department of Chemistry, Columbia University, New York, NY 10027, USA
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12
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Que Y, Chan YH, Jia J, Das A, Tong Z, Chang YT, Cui Z, Kumar A, Singh G, Mukherjee S, Lin H, Weber B. A Gate-Tunable Ambipolar Quantum Phase Transition in a Topological Excitonic Insulator. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2309356. [PMID: 38010877 DOI: 10.1002/adma.202309356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 10/26/2023] [Indexed: 11/29/2023]
Abstract
Coulomb interactions among electrons and holes in 2D semimetals with overlapping valence and conduction bands can give rise to a correlated insulating ground state via exciton formation and condensation. One candidate material in which such excitonic state uniquely combines with non-trivial band topology are atomic monolayers of tungsten ditelluride (WTe2 ), in which a 2D topological excitonic insulator (2D TEI) forms. However, the detailed mechanism of the 2D bulk gap formation in WTe2 , in particular with regard to the role of Coulomb interactions, has remained a subject of ongoing debate. Here, it shows that WTe2 is susceptible to a gate-tunable quantum phase transition, evident from an abrupt collapse of its 2D bulk energy gap upon ambipolar field-effect doping. Such gate tunability of a 2D TEI, into either n- and p-type semimetals, promises novel handles of control over non-trivial 2D superconductivity with excitonic pairing.
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Affiliation(s)
- Yande Que
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Yang-Hao Chan
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 106319, Taiwan
- Physics Division, National Center of Theoretical Physics, Taipei, 10617, Taiwan
| | - Junxiang Jia
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Anirban Das
- Department of Physics, Indian Institute of Technology Madras, Chennai, Tamil Nadu, 600036, India
- Center for Atomistic Modelling and Materials Design, Indian Institute of Technology Madras, Chennai, Tamil Nadu, 600036, India
| | - Zhengjue Tong
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Yu-Tzu Chang
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 106319, Taiwan
| | - Zhenhao Cui
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Amit Kumar
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Gagandeep Singh
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Shantanu Mukherjee
- Department of Physics, Indian Institute of Technology Madras, Chennai, Tamil Nadu, 600036, India
- Center for Atomistic Modelling and Materials Design, Indian Institute of Technology Madras, Chennai, Tamil Nadu, 600036, India
- Quantum Centre for Diamond and Emergent Materials, Indian Institute of Technology Madras, Chennai, Tamil Nadu, 600036, India
| | - Hsin Lin
- Institute of Physics, Academia Sinica, Taipei, 115201, Taiwan
| | - Bent Weber
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
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13
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Liu H, Wang J, Chen S, Sun Z, Xu H, Han Y, Wang C, Liu H, Huang L, Luo J, Liu D. Direct Visualization of Dark Interlayer Exciton Transport in Moiré Superlattices. NANO LETTERS 2024; 24:339-346. [PMID: 38147355 DOI: 10.1021/acs.nanolett.3c04105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2023]
Abstract
Moiré superlattices have emerged as an unprecedented manipulation tool for engineering correlated quantum phenomena in van der Waals heterostructures. With moiré potentials as a naturally configurable solid-state that sustains high exciton density, interlayer excitons in transition metal dichalcogenide heterostructures are expected to achieve high-temperature exciton condensation. However, the exciton degeneracy state is usually optically inactive due to the finite momentum of interlayer excitons. Experimental observation of dark interlayer excitons in moiré potentials remains challenging. Here we directly visualize the dark interlayer exciton transport in WS2/h-BN/WSe2 heterostructures using femtosecond transient absorption microscopy. We observe a transition from classical free exciton gas to quantum degeneracy by imaging temperature-dependent exciton transport. Below a critical degeneracy temperature, exciton diffusion rates exhibit an accelerating downward trend, which can be explained well by a nonlinear quantum diffusion model. These results open the door to quantum information processing and high-precision metrology in moiré superlattices.
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Affiliation(s)
- Huan Liu
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
| | - Jiangcai Wang
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
| | - Shihong Chen
- School of Resources, Environment and Materials, Guangxi University, Nanning 530004, China
| | - Zejun Sun
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
| | - Haowen Xu
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China
| | - Yishu Han
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
| | - Chong Wang
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
| | - Huixian Liu
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
| | - Li Huang
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
| | - Jianbin Luo
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
| | - Dameng Liu
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
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14
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Wietek E, Florian M, Göser J, Taniguchi T, Watanabe K, Högele A, Glazov MM, Steinhoff A, Chernikov A. Nonlinear and Negative Effective Diffusivity of Interlayer Excitons in Moiré-Free Heterobilayers. PHYSICAL REVIEW LETTERS 2024; 132:016202. [PMID: 38242648 DOI: 10.1103/physrevlett.132.016202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 11/10/2023] [Indexed: 01/21/2024]
Abstract
Interlayer exciton diffusion is studied in atomically reconstructed MoSe_{2}/WSe_{2} heterobilayers with suppressed disorder. Local atomic registry is confirmed by characteristic optical absorption, circularly polarized photoluminescence, and g-factor measurements. Using transient microscopy we observe propagation properties of interlayer excitons that are independent from trapping at moiré- or disorder-induced local potentials. Confirmed by characteristic temperature dependence for free particles, linear diffusion coefficients of interlayer excitons at liquid helium temperature and low excitation densities are almost 1000 times higher than in previous observations. We further show that exciton-exciton repulsion and annihilation contribute nearly equally to nonlinear propagation by disentangling the two processes in the experiment and simulations. Finally, we demonstrate effective shrinking of the light emission area over time across several hundreds of picoseconds at the transition from exciton- to the plasma-dominated regimes. Supported by microscopic calculations for band gap renormalization to identify the Mott threshold, this indicates transient crossing between rapidly expanding, short-lived electron-hole plasma and slower, long-lived exciton populations.
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Affiliation(s)
- Edith Wietek
- Institute of Applied Physics and Würzburg-Dresden Cluster of Excellence ct.qmat, Technische Universität Dresden, 01062 Dresden, Germany
| | - Matthias Florian
- Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Jonas Göser
- Fakultät für Physik, Munich Quantum Center, and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, 80539 München, Germany
| | - Takashi Taniguchi
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Kenji Watanabe
- Research Center for Electronic and Optical Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Alexander Högele
- Fakultät für Physik, Munich Quantum Center, and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, 80539 München, Germany
- Munich Center for Quantum Science and Technology (MCQST), 80799 München, Germany
| | | | - Alexander Steinhoff
- Institut für Theoretische Physik, Universität Bremen, 28334 Bremen, Germany
- Bremen Center for Computational Materials Science, Universität Bremen, 28334 Bremen, Germany
| | - Alexey Chernikov
- Institute of Applied Physics and Würzburg-Dresden Cluster of Excellence ct.qmat, Technische Universität Dresden, 01062 Dresden, Germany
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15
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Bai Y, Li Y, Liu S, Guo Y, Pack J, Wang J, Dean CR, Hone J, Zhu X. Evidence for Exciton Crystals in a 2D Semiconductor Heterotrilayer. NANO LETTERS 2023; 23:11621-11629. [PMID: 38071655 DOI: 10.1021/acs.nanolett.3c03453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2023]
Abstract
Two-dimensional (2D) transition metal dichalcogenides (TMDC) and their moiré interfaces have been demonstrated for correlated electron states, including Mott insulators and electron/hole crystals commensurate with moiré superlattices. Here we present spectroscopic evidence for ordered bosons─interlayer exciton crystals in a WSe2/MoSe2/WSe2 trilayer, where the enhanced Coulomb interactions over those in heterobilayers have been predicted to result in exciton ordering. Ordered interlayer excitons in the trilayer are characterized by negligible mobility and by sharper PL peaks persisting to an exciton density of nex ∼ 1012 cm-2, which is an order of magnitude higher than the corresponding limit in the heterobilayer. We present evidence for the predicted quadrupolar exciton crystal and its transitions to dipolar excitons either with increasing nex or by an applied electric field. These ordered interlayer excitons may serve as models for the exploration of quantum phase transitions and quantum coherent phenomena.
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Affiliation(s)
- Yusong Bai
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Yiliu Li
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Song Liu
- Department of Mechanical Engineering, Columbia University, New York, New York 10027, United States
| | - Yinjie Guo
- Department of Physics and Astronomy, Columbia University, New York, New York 10027, United States
| | - Jordan Pack
- Department of Physics and Astronomy, Columbia University, New York, New York 10027, United States
| | - Jue Wang
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Cory R Dean
- Department of Physics and Astronomy, Columbia University, New York, New York 10027, United States
| | - James Hone
- Department of Mechanical Engineering, Columbia University, New York, New York 10027, United States
| | - Xiaoyang Zhu
- Department of Chemistry, Columbia University, New York, New York 10027, United States
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16
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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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17
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Chen W, Huang CJ, Zhu Q. Searching for Unconventional Superfluid in Excitons of Monolayer Semiconductors. PHYSICAL REVIEW LETTERS 2023; 131:236004. [PMID: 38134763 DOI: 10.1103/physrevlett.131.236004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 08/02/2023] [Accepted: 11/01/2023] [Indexed: 12/24/2023]
Abstract
It is well known that two-dimensional (2D) bosons in homogeneous space cannot undergo real Bose-Einstein condensation, and the superfluid to normal phase transition is Berezinskii-Kosterlitz-Thouless (BKT) type, associated with vortex-antivortex pair unbinding. Here we point out a 2D bosonic system whose low energy physics goes beyond conventional paradigm of 2D homogeneous bosons, i.e., intralayer excitons in monolayer transition metal dichalcogenides. With intrinsic valley-orbit coupling and valley Zeeman energy, exciton dispersion becomes linear at small momentum, giving rise to a series of novel features. The critical temperature of Bose-Einstein condensation of these excitons is nonzero, suggesting true long-range order in 2D homogeneous system. The dispersion of Goldstone mode at long wavelength has the form ϵ(q)∼sqrt[q], in contrast to conventional linear phonon spectrum. The vortex energy deviates from the usual logarithmic form with respect to system size, but instead has an additional linear term. Superfluid to normal phase transition is no longer BKT type for system size beyond a characteristic scale, without discontinuous jump in superfluid density. With the recent experimental progress on exciton fluid at thermal equilibrium in monolayer semiconductors, our work points out an experimentally accessible system to search for unconventional 2D superfluids beyond BKT paradigm.
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Affiliation(s)
- Wei Chen
- Guangdong Basic Research Center of Excellence for Structure and Fundamental Interactions of Matter, Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics, South China Normal University, Guangzhou 510006, China
- Guangdong-Hong Kong Joint Laboratory of Quantum Matter, Frontier Research Institute for Physics, South China Normal University, Guangzhou 510006, China
| | - Chun-Jiong Huang
- Department of Physics and HKU-UCAS Joint Institute for Theoretical and Computational Physics at Hong Kong, The University of Hong Kong, Hong Kong, China
| | - Qizhong Zhu
- Guangdong Basic Research Center of Excellence for Structure and Fundamental Interactions of Matter, Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics, South China Normal University, Guangzhou 510006, China
- Guangdong-Hong Kong Joint Laboratory of Quantum Matter, Frontier Research Institute for Physics, South China Normal University, Guangzhou 510006, China
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18
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Li Z, Qin F, Ong CS, Huang J, Xu Z, Chen P, Qiu C, Zhang X, Zhang C, Zhang X, Eriksson O, Rubio A, Tang P, Yuan H. Robustness of Trion State in Gated Monolayer MoSe 2 under Pressure. NANO LETTERS 2023; 23:10282-10289. [PMID: 37906179 DOI: 10.1021/acs.nanolett.3c02812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
Quasiparticles consisting of correlated electron(s) and hole(s), such as excitons and trions, play important roles in the optical phenomena of van der Waals semiconductors and serve as unique platforms for studies of many-body physics. Herein, we report a gate-tunable exciton-to-trion transition in pressurized monolayer MoSe2, in which the electronic band structures are modulated continuously within a diamond anvil cell. The emission energies of both the exciton and trion undergo large blueshifts over 90 meV with increasing pressure. Surprisingly, the trion binding energy remains constant at 30 meV, regardless of the applied pressure. Combining ab initio density functional theory calculations and quantum Monte Carlo simulations, we find that the remarkable robustness of the trion binding energy originates from the spatially diffused nature of the trion wave function and the weak correlation between its constituent electron-hole pairs. Our findings shed light on the optical properties of correlated excitonic quasiparticles in low-dimensional materials.
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Affiliation(s)
- Zeya Li
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- College of Engineering and Applied Sciences, Jiangsu Key Laboratory of Artificial Functional Materials, Nanjing University, Nanjing 210023, China
| | - Feng Qin
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- College of Engineering and Applied Sciences, Jiangsu Key Laboratory of Artificial Functional Materials, Nanjing University, Nanjing 210023, China
| | - Chin Shen Ong
- Department of Physics and Astronomy, Uppsala University, Uppsala 75120, Sweden
| | - Junwei Huang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- College of Engineering and Applied Sciences, Jiangsu Key Laboratory of Artificial Functional Materials, Nanjing University, Nanjing 210023, China
| | - Zian Xu
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
| | - Peng Chen
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- College of Engineering and Applied Sciences, Jiangsu Key Laboratory of Artificial Functional Materials, Nanjing University, Nanjing 210023, China
| | - Caiyu Qiu
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- College of Engineering and Applied Sciences, Jiangsu Key Laboratory of Artificial Functional Materials, Nanjing University, Nanjing 210023, China
| | - Xi Zhang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- School of Physics, Nanjing University, Nanjing 210000, China
| | - Caorong Zhang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- School of Physics, Nanjing University, Nanjing 210000, China
| | - Xiuxiu Zhang
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
| | - Olle Eriksson
- Department of Physics and Astronomy, Uppsala University, Uppsala 75120, Sweden
- School of Science and Technology, Örebro University, Örebro 70182, Sweden
| | - Angel Rubio
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free-Electron Laser Science, Hamburg 22761, Germany
- Center for Computational Quantum Physics, Simons Foundation Flatiron Institute, New York 10010, United States
- Nano-Bio Spectroscopy Group, University of the Basque Country (UPV/EHU), San Sebastián 20018, Spain
| | - Peizhe Tang
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free-Electron Laser Science, Hamburg 22761, Germany
| | - Hongtao Yuan
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- College of Engineering and Applied Sciences, Jiangsu Key Laboratory of Artificial Functional Materials, Nanjing University, Nanjing 210023, China
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19
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Fang H, Lin Q, Zhang Y, Thompson J, Xiao S, Sun Z, Malic E, Dash SP, Wieczorek W. Localization and interaction of interlayer excitons in MoSe 2/WSe 2 heterobilayers. Nat Commun 2023; 14:6910. [PMID: 37903787 PMCID: PMC10616232 DOI: 10.1038/s41467-023-42710-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 10/19/2023] [Indexed: 11/01/2023] Open
Abstract
Transition metal dichalcogenide (TMD) heterobilayers provide a versatile platform to explore unique excitonic physics via the properties of the constituent TMDs and external stimuli. Interlayer excitons (IXs) can form in TMD heterobilayers as delocalized or localized states. However, the localization of IX in different types of potential traps, the emergence of biexcitons in the high-excitation regime, and the impact of potential traps on biexciton formation have remained elusive. In our work, we observe two types of potential traps in a MoSe2/WSe2 heterobilayer, which result in significantly different emission behavior of IXs at different temperatures. We identify the origin of these traps as localized defect states and the moiré potential of the TMD heterobilayer. Furthermore, with strong excitation intensity, a superlinear emission behavior indicates the emergence of interlayer biexcitons, whose formation peaks at a specific temperature. Our work elucidates the different excitation and temperature regimes required for the formation of both localized and delocalized IX and biexcitons and, thus, contributes to a better understanding and application of the rich exciton physics in TMD heterostructures.
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Affiliation(s)
- Hanlin Fang
- Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, 41296, Gothenburg, Sweden.
| | - Qiaoling Lin
- Department of Electrical and Photonics Engineering, Technical University of Denmark, DK-2800, Kongens Lyngby, Denmark
| | - Yi Zhang
- Department of Electronics and Nanoengineering and QTF Centre of Excellence, Aalto University, Espoo, 02150, Finland
| | - Joshua Thompson
- Department of Physics, Philipps-Universität Marburg, 35037, Marburg, Germany
| | - Sanshui Xiao
- Department of Electrical and Photonics Engineering, Technical University of Denmark, DK-2800, Kongens Lyngby, Denmark
| | - Zhipei Sun
- Department of Electronics and Nanoengineering and QTF Centre of Excellence, Aalto University, Espoo, 02150, Finland
| | - Ermin Malic
- Department of Physics, Philipps-Universität Marburg, 35037, Marburg, Germany
| | - Saroj P Dash
- Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, 41296, Gothenburg, Sweden
| | - Witlef Wieczorek
- Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, 41296, Gothenburg, Sweden.
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20
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Kohler DD, Morrow DJ, Zhao Y, Scheeler JM, Jin S, Wright JC. Photoluminescence, Reflection Contrast, Raman, and Second Harmonic Generation Spectroscopies Spatially Resolve Strain, Alloying, Defects, and Electronic Characteristics of Lateral MX 2 Heterostructures. J Phys Chem Lett 2023; 14:9424-9432. [PMID: 37824438 DOI: 10.1021/acs.jpclett.3c02407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2023]
Abstract
Lateral heterostructures of two-dimensional (2D) transition metal dichalcogenides offer promise as platforms for a wide variety of applications from exotic physics to environmental control. Further development and study of these heterostructures require characterization methods that assess the quality of the heterostructures. Here, we extend current characterization strategies to create photoluminescence (PL), Raman, reflection contrast, and second harmonic generation (SHG) maps of individual monolayer core-shell WS2-MoS2 lateral heterostructures that were synthesized via water vapor assisted chemical vapor transport. Together, these methods provide the correlations required to resolve the effects of excitons, trions, lattice defects, strain, and alloying. The comparisons show substantial differences, especially in the regions near and at the narrow heterointerface. Comparisons between the different spectral maps show the importance of metal alloying for understanding the electronic and spatial structures of heterostructures. The results are compared to previous work on similar lateral heterostructures created by different methods.
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Affiliation(s)
- Daniel D Kohler
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Darien J Morrow
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Yuzhou Zhao
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Jason M Scheeler
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Song Jin
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - John C Wright
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
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21
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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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22
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Aly MA, Enakerakpor EO, Koch M, Masenda H. Tuning Interlayer Exciton Emission with TMD Alloys in van der Waals Heterobilayers of Mo 0.5W 0.5Se 2 and Its Binary Counterparts. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2769. [PMID: 37887920 PMCID: PMC10609229 DOI: 10.3390/nano13202769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 10/12/2023] [Accepted: 10/14/2023] [Indexed: 10/28/2023]
Abstract
Semiconductor heterostructures have been the backbone of developments in electronic and optoelectronic devices. One class of structures of interest is the so-called type II band alignment, in which optically excited electrons and holes relax into different material layers. The unique properties observed in two-dimensional transition metal dichalcogenides and the possibility to engineer van der Waals heterostructures make them candidates for future high-tech devices. In these structures, electronic, optical, and magnetic properties can be tuned through the interlayer coupling, thereby opening avenues for developing new functional materials. We report the possibility of explicitly tuning the emission of interlayer exciton energies in the binary-ternary heterobilayer of Mo0.5W0.5Se2 with MoSe2 and WSe2. The respective interlayer energies of 1.516 eV and 1.490 eV were observed from low-temperature photoluminescence measurements for the MoSe2- and WSe2- based heterostructures, respectively. These interlayer emission energies are above those reported for MoSe2/WSe2 (≃1.30-1.45 eV). Consequently, binary-ternary heterostructure systems offer an extended energy range and tailored emission energies not accessible with the binary counterparts. Moreover, even though Mo0.5W0.5Se2 and MoSe2 have almost similar optical gaps, their band offsets are different, resulting in charge transfer between the monolayers following the optical excitation. Thus, confirming TMDs alloys can be used to tune the band-offsets, which adds another design parameter for application-specific optoelectronic devices.
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Affiliation(s)
- Mohammed Adel Aly
- Faculty of Physics and Materials Sciences Center, Philipps-Universität Marburg, 35032 Marburg, Germany
- Department of Physics, Faculty of Science, Ain Shams University, Cairo 11566, Egypt
| | | | - Martin Koch
- Faculty of Physics and Materials Sciences Center, Philipps-Universität Marburg, 35032 Marburg, Germany
| | - Hilary Masenda
- Faculty of Physics and Materials Sciences Center, Philipps-Universität Marburg, 35032 Marburg, Germany
- School of Physics, University of the Witwatersrand, Johannesburg 2050, South Africa
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23
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Davis ML, Parolo S, Reichl C, Dietsche W, Wegscheider W. Josephson-like Tunnel Resonance and Large Coulomb Drag in GaAs-Based Electron-Hole Bilayers. PHYSICAL REVIEW LETTERS 2023; 131:156301. [PMID: 37897778 DOI: 10.1103/physrevlett.131.156301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 09/05/2023] [Indexed: 10/30/2023]
Abstract
Bilayers consisting of two-dimensional (2D) electron and hole gases separated by a 10 nm thick AlGaAs barrier are formed by charge accumulation in epitaxially grown GaAs. Both vertical and lateral electric transport are measured in the millikelvin temperature range. The conductivity between the layers shows a sharp tunnel resonance at a density of 1.1×10^{10} cm^{-2}, which is consistent with a Josephson-like enhanced tunnel conductance. The tunnel resonance disappears with increasing densities and the two 2D charge gases start to show 2D-Fermi-gas behavior. Interlayer interactions persist causing a positive drag voltage that is very large at small densities. The transition from the Josephson-like tunnel resonance to the Fermi-gas behavior is interpreted as a phase transition from an exciton gas in the Bose-Einstein-condensate state to a degenerate electron-hole Fermi gas.
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Affiliation(s)
- M L Davis
- Solid State Physics Laboratory, ETH Zürich, CH-8093 Zürich, Switzerland
| | - S Parolo
- Solid State Physics Laboratory, ETH Zürich, CH-8093 Zürich, Switzerland
| | - C Reichl
- Solid State Physics Laboratory, ETH Zürich, CH-8093 Zürich, Switzerland
| | - W Dietsche
- Solid State Physics Laboratory, ETH Zürich, CH-8093 Zürich, Switzerland
- Max-Planck-Institut für Festkörperforschung, D-70569 Stuttgart, Germany
| | - W Wegscheider
- Solid State Physics Laboratory, ETH Zürich, CH-8093 Zürich, Switzerland
- Quantum Center, ETH Zürich, CH-8093 Zürich, Switzerland
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24
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Baghdasaryan DA, Harutyunyan VA, Kazaryan EM, Sarkisyan HA, Petrosyan LS, Shahbazyan TV. Possibility of Exciton Bose-Einstein Condensation in CdSe Nanoplatelets. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2734. [PMID: 37836375 PMCID: PMC10574473 DOI: 10.3390/nano13192734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 10/01/2023] [Accepted: 10/06/2023] [Indexed: 10/15/2023]
Abstract
The quasi-two-dimensional exciton subsystem in CdSe nanoplatelets is considered. It is theoretically shown that Bose-Einstein condensation (BEC) of excitons is possible at a nonzero temperature in the approximation of an ideal Bose gas and in the presence of an "energy gap" between the ground and the first excited states of the two-dimensional exciton center of inertia of the translational motion. The condensation temperature (Tc) increases with the width of the "gap" between the ground and the first excited levels of size quantization. It is shown that when the screening effect of free electrons and holes on bound excitons is considered, the BEC temperature of the exciton subsystem increases as compared to the case where this effect is absent. The energy spectrum of the exciton condensate in a CdSe nanoplate is calculated within the framework of the weakly nonideal Bose gas approximation, considering the specifics of two-dimensional Born scattering.
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Affiliation(s)
- Davit A. Baghdasaryan
- Institute of Engineering and Physics, Russian-Armenian University, H. Emin 123, Yerevan 0051, Armenia; (D.A.B.); (V.A.H.); (E.M.K.)
| | - Volodya A. Harutyunyan
- Institute of Engineering and Physics, Russian-Armenian University, H. Emin 123, Yerevan 0051, Armenia; (D.A.B.); (V.A.H.); (E.M.K.)
| | - Eduard M. Kazaryan
- Institute of Engineering and Physics, Russian-Armenian University, H. Emin 123, Yerevan 0051, Armenia; (D.A.B.); (V.A.H.); (E.M.K.)
| | - Hayk A. Sarkisyan
- Institute of Engineering and Physics, Russian-Armenian University, H. Emin 123, Yerevan 0051, Armenia; (D.A.B.); (V.A.H.); (E.M.K.)
- Institute of Electronics and Telecommunications, Peter the Great Saint-Petersburg Polytechnical University, 195251 Saint-Petersburg, Russia
| | - Lyudvig S. Petrosyan
- Department of Physics, Jackson State University, Jackson, MS 39217, USA; (L.S.P.); (T.V.S.)
| | - Tigran V. Shahbazyan
- Department of Physics, Jackson State University, Jackson, MS 39217, USA; (L.S.P.); (T.V.S.)
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25
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Cong X, Mohammadi PA, Zheng M, Watanabe K, Taniguchi T, Rhodes D, Zhang XX. Interplay of valley polarized dark trion and dark exciton-polaron in monolayer WSe 2. Nat Commun 2023; 14:5657. [PMID: 37704654 PMCID: PMC10500002 DOI: 10.1038/s41467-023-41475-4] [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: 05/14/2023] [Accepted: 09/06/2023] [Indexed: 09/15/2023] Open
Abstract
The interactions between charges and excitons involve complex many-body interactions at high densities. The exciton-polaron model has been adopted to understand the Fermi sea screening of charged excitons in monolayer transition metal dichalcogenides. The results provide good agreement with absorption measurements, which are dominated by dilute bright exciton responses. Here we investigate the Fermi sea dressing of spin-forbidden dark excitons in monolayer WSe2. With a Zeeman field, the valley-polarized dark excitons show distinct p-doping dependence in photoluminescence when the carriers reach a critical density. This density can be interpreted as the onset of strongly modified Fermi sea interactions and shifts with increasing exciton density. Through valley-selective excitation and dynamics measurements, we also infer an intervalley coupling between the dark trions and exciton-polarons mediated by the many-body interactions. Our results reveal the evolution of Fermi sea screening with increasing exciton density and the impacts of polaron-polaron interactions, which lay the foundation for understanding electronic correlations and many-body interactions in 2D systems.
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Affiliation(s)
- Xin Cong
- Department of Physics, University of Florida, Gainesville, FL, USA
| | | | - Mingyang Zheng
- Department of Physics, University of Florida, Gainesville, FL, USA
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Japan
| | - Daniel Rhodes
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Xiao-Xiao Zhang
- Department of Physics, University of Florida, Gainesville, FL, USA.
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26
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Vedhanth SVU, Datta S. Direct determination of 2D momentum space from 2D spatial coherence of light using a modified Michelson interferometer. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2023; 94:095113. [PMID: 37737701 DOI: 10.1063/5.0160614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Accepted: 08/30/2023] [Indexed: 09/23/2023]
Abstract
Momentum space distribution of photons coming out of any light emitting material/device provides critical information about their underlying physical origin. Conventional methods of determining such properties impose specific instrumentational difficulties for probing samples kept within a low temperature cryostat. There were past studies to measure a one-dimensional coherence function, which could then be used for extracting momentum space information, as well as reports of measurements of just a two-dimensional (2D) coherence function. However, all of those are associated with additional experimental complexities. So, here we propose a simpler, modified Michelson interferometer based optical setup that is kept at room temperature and placed outside the low temperature cryostat at a distance away from it. We initially measure the 2D coherence function of emitted light, which can then be used to directly estimate the 2D in-plane momentum space distribution by calculating its fast Fourier transform. We also discuss how this experimental method can overcome instrumentational difficulties encountered in the past. Similar instrumentations can also be extended for momentum space resolved astronomical studies and telecommunications involving distant light sources.
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Affiliation(s)
- S V U Vedhanth
- Department of Physics, Indian Institute of Science Education and Research, Pune 411008, Maharashtra, India
| | - Shouvik Datta
- Department of Physics, Indian Institute of Science Education and Research, Pune 411008, Maharashtra, India
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27
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Liu T, Fu Q, Li Y, Han X, Wang S, Taniguchi T, Watanabe K, Wan D, Zhang Q, Zhao Y, Ni Z, Ding F, Hu Z, Yuan X, Lu J. Silver nanoparticle-induced enhancement of light extraction in two-dimensional light-emitting diodes. OPTICS LETTERS 2023; 48:4372-4375. [PMID: 37582035 DOI: 10.1364/ol.498850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 07/26/2023] [Indexed: 08/17/2023]
Abstract
Monolayer transition metal dichalcogenides (TMDCs) with direct bandgaps are considered promising candidates for building light-emitting diodes (LEDs). One crucial indicator of their performance is the brightness of electroluminescence (EL). In this study, we fabricate WS2-based LEDs that make full use of the assistance of effective transient-mode charge injection. By introducing self-assembled silver nanoparticles (NPs) on top of the LED, the extraction efficiency is significantly improved, with a 2.9-fold EL enhancement observed in the experiment. Full-wave simulations further confirm that the improvement comes from the scattering capability of silver NPs, with results qualitatively fitting the experiment. This approach, with its compatibility with van der Waals heterostructures, can be further promoted to enhance the brightness of 2D monolayer TMDC-based LEDs.
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28
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Hsieh YC, Lin ZY, Fung SJ, Lu WS, Ho SC, Hong SP, Ho SZ, Huang CH, Watanabe K, Taniguchi T, Chan YH, Chen YC, Wu CL, Chen TM. Engineering the Strain and Interlayer Excitons of 2D Materials via Lithographically Engraved Hexagonal Boron Nitride. NANO LETTERS 2023; 23:7244-7251. [PMID: 37348137 DOI: 10.1021/acs.nanolett.3c01208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/24/2023]
Abstract
Strain engineering has quickly emerged as a viable option to modify the electronic, optical, and magnetic properties of 2D materials. However, it remains challenging to arbitrarily control the strain. Here we show that, by creating atomically flat surface nanostructures in hexagonal boron nitride, we achieve an arbitrary on-chip control of both the strain distribution and magnitude on high-quality molybdenum disulfide. The phonon and exciton emissions are shown to vary in accordance with our strain field designs, enabling us to write and draw any photoluminescence color image in a single chip. Moreover, our strain engineering offers a powerful means to significantly and controllably alter the strengths and energies of interlayer excitons at room temperature. This method can be easily extended to other material systems and offers promise for functional excitonic devices.
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Affiliation(s)
- Yu-Chiang Hsieh
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
| | - Zhen-You Lin
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
| | - Shin-Ji Fung
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
| | - Wen-Shin Lu
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan
- Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
| | - Sheng-Chin Ho
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
| | - Siang-Ping Hong
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
| | - Sheng-Zhu Ho
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
| | - Chiu-Hua Huang
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Namiki 1-1, Tsukuba, 305-0044, Ibaraki, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Namiki 1-1, Tsukuba, 305-0044, Ibaraki, Japan
| | - Yang-Hao Chan
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan
- Physics Division, National Center for Theoretical Sciences, Taipei 106, Taiwan
| | - Yi-Chun Chen
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
- Center for Quantum Frontiers of Research & Technology (QFort), National Cheng Kung University, Tainan 701, Taiwan
| | - Chung-Lin Wu
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
- Center for Quantum Frontiers of Research & Technology (QFort), National Cheng Kung University, Tainan 701, Taiwan
| | - Tse-Ming Chen
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
- Center for Quantum Frontiers of Research & Technology (QFort), National Cheng Kung University, Tainan 701, Taiwan
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29
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Lian Z, Chen D, Ma L, Meng Y, Su Y, Yan L, Huang X, Wu Q, Chen X, Blei M, Taniguchi T, Watanabe K, Tongay S, Zhang C, Cui YT, Shi SF. Quadrupolar excitons and hybridized interlayer Mott insulator in a trilayer moiré superlattice. Nat Commun 2023; 14:4604. [PMID: 37528094 PMCID: PMC10393975 DOI: 10.1038/s41467-023-40288-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Accepted: 07/21/2023] [Indexed: 08/03/2023] Open
Abstract
Transition metal dichalcogenide (TMDC) moiré superlattices, owing to the moiré flatbands and strong correlation, can host periodic electron crystals and fascinating correlated physics. The TMDC heterojunctions in the type-II alignment also enable long-lived interlayer excitons that are promising for correlated bosonic states, while the interaction is dictated by the asymmetry of the heterojunction. Here we demonstrate a new excitonic state, quadrupolar exciton, in a symmetric WSe2-WS2-WSe2 trilayer moiré superlattice. The quadrupolar excitons exhibit a quadratic dependence on the electric field, distinctively different from the linear Stark shift of the dipolar excitons in heterobilayers. This quadrupolar exciton stems from the hybridization of WSe2 valence moiré flatbands. The same mechanism also gives rise to an interlayer Mott insulator state, in which the two WSe2 layers share one hole laterally confined in one moiré unit cell. In contrast, the hole occupation probability in each layer can be continuously tuned via an out-of-plane electric field, reaching 100% in the top or bottom WSe2 under a large electric field, accompanying the transition from quadrupolar excitons to dipolar excitons. Our work demonstrates a trilayer moiré system as a new exciting playground for realizing novel correlated states and engineering quantum phase transitions.
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Affiliation(s)
- Zhen Lian
- Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA
| | - Dongxue Chen
- Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA
| | - Lei Ma
- Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA
| | - Yuze Meng
- Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA
| | - Ying Su
- Department of Physics, University of Texas at Dallas, Dallas, TX, 75083, USA
| | - Li Yan
- Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA
| | - Xiong Huang
- Department of Physics and Astronomy, University of California, Riverside, CA, 92521, USA
- Department of Materials Science and Engineering, University of California, Riverside, CA, 92521, USA
| | - Qiran Wu
- Department of Physics and Astronomy, University of California, Riverside, CA, 92521, USA
| | - Xinyue Chen
- Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA
| | - Mark Blei
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, 85287, 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
| | - Sefaattin Tongay
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, 85287, USA
| | - Chuanwei Zhang
- Department of Physics, University of Texas at Dallas, Dallas, TX, 75083, USA
| | - Yong-Tao Cui
- Department of Physics and Astronomy, University of California, Riverside, CA, 92521, USA.
| | - Su-Fei Shi
- Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA.
- Department of Electrical, Computer & Systems Engineering, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA.
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30
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Guo H, Zhang X, Lu G. Pseudo-heterostructure and condensation of 1D moiré excitons in twisted phosphorene bilayers. SCIENCE ADVANCES 2023; 9:eadi5404. [PMID: 37478184 PMCID: PMC10361592 DOI: 10.1126/sciadv.adi5404] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 06/20/2023] [Indexed: 07/23/2023]
Abstract
Heterostructures are not expected to form in a single homogeneous material. Here, we show that planar pseudo-heterostructures could emerge in a twisted bilayer of phosphorene (tbP), driving in-plane energy and charge transfer. The formation of moiré superlattices combined with electronic anisotropy in tbPs yields one-dimensional (1D) moiré excitons with long radiative and nonradiative lifetimes, large binding energies, and deep moiré potentials. Low-frequency moiré phonons and dynamic moiré potentials are revealed to be responsible for the in-plane energy/charge transfer and exciton dynamics. The 1D moiré excitons are predicted to exhibit Bose-Einstein condensation at high temperatures and may lead to exotic Tonks-Girardeau Bose gases.
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Affiliation(s)
- Hongli Guo
- Department of Physics and Astronomy, California State University Northridge, Northridge, CA 91330-8268, USA
| | - Xu Zhang
- Department of Physics and Astronomy, California State University Northridge, Northridge, CA 91330-8268, USA
| | - Gang Lu
- Department of Physics and Astronomy, California State University Northridge, Northridge, CA 91330-8268, USA
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31
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Troue M, Figueiredo J, Sigl L, Paspalides C, Katzer M, Taniguchi T, Watanabe K, Selig M, Knorr A, Wurstbauer U, Holleitner AW. Extended Spatial Coherence of Interlayer Excitons in MoSe_{2}/WSe_{2} Heterobilayers. PHYSICAL REVIEW LETTERS 2023; 131:036902. [PMID: 37540866 DOI: 10.1103/physrevlett.131.036902] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 06/09/2023] [Indexed: 08/06/2023]
Abstract
We report on the spatial coherence of interlayer exciton ensembles as formed in MoSe_{2}/WSe_{2} heterostructures and characterized by point-inversion Michelson-Morley interferometry. Below 10 K, the measured spatial coherence length of the interlayer excitons reaches values equivalent to the lateral expansion of the exciton ensembles. In this regime, the light emission of the excitons turns out to be homogeneously broadened in energy with a high temporal coherence. At higher temperatures, both the spatial coherence length and the temporal coherence time decrease, most likely because of thermal processes. The presented findings point towards a spatially extended, coherent many-body state of interlayer excitons at low temperature.
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Affiliation(s)
- Mirco Troue
- Walter Schottky Institute and Physics Department, Technical University of Munich, Am Coulombwall 4a, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstr. 4, 80799 Munich, Germany
| | - Johannes Figueiredo
- Walter Schottky Institute and Physics Department, Technical University of Munich, Am Coulombwall 4a, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstr. 4, 80799 Munich, Germany
| | - Lukas Sigl
- Walter Schottky Institute and Physics Department, Technical University of Munich, Am Coulombwall 4a, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstr. 4, 80799 Munich, Germany
| | - Christos Paspalides
- Walter Schottky Institute and Physics Department, Technical University of Munich, Am Coulombwall 4a, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstr. 4, 80799 Munich, Germany
| | - Manuel Katzer
- Institute for Theoretical Physics, Nonlinear Optics and Quantum Electronics, Technical University of Berlin, 10623 Berlin, Germany
| | - Takashi Taniguchi
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Kenji Watanabe
- Research Center for Electronic and Optical Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Malte Selig
- Institute for Theoretical Physics, Nonlinear Optics and Quantum Electronics, Technical University of Berlin, 10623 Berlin, Germany
| | - Andreas Knorr
- Institute for Theoretical Physics, Nonlinear Optics and Quantum Electronics, Technical University of Berlin, 10623 Berlin, Germany
| | - Ursula Wurstbauer
- Institute of Physics, Münster University, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany
| | - Alexander W Holleitner
- Walter Schottky Institute and Physics Department, Technical University of Munich, Am Coulombwall 4a, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstr. 4, 80799 Munich, Germany
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32
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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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33
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Li L, Yao J, Zhu J, Chen Y, Wang C, Zhou Z, Zhao G, Zhang S, Wang R, Li J, Wang X, Lu Z, Xiao L, Zhang Q, Zou G. Colloid driven low supersaturation crystallization for atomically thin Bismuth halide perovskite. Nat Commun 2023; 14:3764. [PMID: 37353502 DOI: 10.1038/s41467-023-39445-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 06/13/2023] [Indexed: 06/25/2023] Open
Abstract
It is challenging to grow atomically thin non-van der Waals perovskite due to the strong electronic coupling between adjacent layers. Here, we present a colloid-driven low supersaturation crystallization strategy to grow atomically thin Cs3Bi2Br9. The colloid solution drives low-concentration solute in a supersaturation state, contributing to initial heterogeneous nucleation. Simultaneously, the colloids provide a stable precursor source in the low-concentration solute. The surfactant is absorbed in specific crystal nucleation facet resulting in the anisotropic growth of planar dominance. Ionic perovskite Cs3Bi2Br9 is readily grown from monolayered to six-layered Cs3Bi2Br9 corresponding to thicknesses of 0.7, 1.6, 2.7, 3.6, 4.6 and 5.7 nm. The atomically thin Cs3Bi2Br9 presents layer-dependent nonlinear optical performance and stacking-induced second harmonic generation. This work provides a concept for growing atomically thin halide perovskite with non-van der Waal structures and demonstrates potential application for atomically thin single crystals' growth with strong electronic coupling between adjacent layers.
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Affiliation(s)
- Lutao Li
- College of Energy, Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou, 215006, China
| | - Junjie Yao
- College of Energy, Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou, 215006, China
| | - Juntong Zhu
- College of Energy, Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou, 215006, China
| | - Yuan Chen
- College of Mechanical and Electronic Engineering, Shandong University of Science and Technology, Qingdao, 266590, China
| | - Chen Wang
- College of Mechanical and Electronic Engineering, Shandong University of Science and Technology, Qingdao, 266590, China
| | - Zhicheng Zhou
- College of Energy, Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou, 215006, China
| | - Guoxiang Zhao
- College of Energy, Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou, 215006, China
| | - Sihan Zhang
- College of Energy, Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou, 215006, China
| | - Ruonan Wang
- College of Energy, Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou, 215006, China
| | - Jiating Li
- College of Energy, Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou, 215006, China
| | - Xiangyi Wang
- College of Energy, Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou, 215006, China
| | - Zheng Lu
- College of Energy, Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou, 215006, China
| | - Lingbo Xiao
- College of Energy, Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou, 215006, China
| | - Qiang Zhang
- College of Mechanical and Electronic Engineering, Shandong University of Science and Technology, Qingdao, 266590, China
| | - Guifu Zou
- College of Energy, Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou, 215006, China.
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34
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Li Y, Yuan Q, Guo D, Lou C, Cui X, Mei G, Petek H, Cao L, Ji W, Feng M. 1D Electronic Flat Bands in Untwisted Moiré Superlattices. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2300572. [PMID: 37057612 DOI: 10.1002/adma.202300572] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 04/03/2023] [Indexed: 06/16/2023]
Abstract
After the preparation of 2D electronic flat band (EFB) in van der Waals (vdW) superlattices, recent measurements suggest the existence of 1D electronic flat bands (1D-EFBs) in twisted vdW bilayers. However, the realization of 1D-EFBs is experimentally elusive in untwisted 2D layers, which is desired considering their fabrication and scalability. Herein, the discovery of 1D-EFBs is reported in an untwisted in situ-grown two atomic-layer Bi(110) superlattice self-aligned on an SnSe(001) substrate using scanning probe microscopy measurements and density functional theory calculations. While the Bi-Bi dimers of Bi zigzag (ZZ) chains are buckled, the epitaxial lattice mismatch between the Bi and SnSe layers induces two 1D buckling reversal regions (BRRs) extending along the ZZ direction in each Bi(110)-11 × 11 supercell. A series of 1D-EFBs arises spatially following BRRs that isolate electronic states along the armchair (AC) direction and localize electrons in 1D extended states along ZZ due to quantum interference at a topological node. This work provides a generalized strategy for engineering 1D-EFBs in utilizing lattice mismatch between untwisted rectangular vdW layers.
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Affiliation(s)
- Yafei Li
- School of Physics and Technology and Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education, Wuhan University, Wuhan, 430072, P. R. China
| | - Qing Yuan
- School of Physics and Technology and Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education, Wuhan University, Wuhan, 430072, P. R. China
| | - Deping Guo
- Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-Nano Devices, Department of Physics, Renmin University of China, Beijing, 100872, P. R. China
- Key Laboratory of Quantum State Construction and Manipulation (Ministry of Education), Renmin Universiry of China, Beijing, 100872, P. R. China
| | - Cancan Lou
- School of Physics and Technology and Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education, Wuhan University, Wuhan, 430072, P. R. China
| | - Xingxia Cui
- School of Physics and Technology and Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education, Wuhan University, Wuhan, 430072, P. R. China
| | - Guangqiang Mei
- School of Physics and Technology and Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education, Wuhan University, Wuhan, 430072, P. R. China
| | - Hrvoje Petek
- Department of Physics and Astronomy and the IQ Initiative, University of Pittsburgh, Pittsburgh, 15260, USA
| | - Limin Cao
- School of Physics and Technology and Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education, Wuhan University, Wuhan, 430072, P. R. China
| | - Wei Ji
- Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-Nano Devices, Department of Physics, Renmin University of China, Beijing, 100872, P. R. China
- Key Laboratory of Quantum State Construction and Manipulation (Ministry of Education), Renmin Universiry of China, Beijing, 100872, P. R. China
| | - Min Feng
- School of Physics and Technology and Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education, Wuhan University, Wuhan, 430072, P. R. China
- Institute for Advanced Study, Wuhan University, Wuhan, 430072, P. R. China
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35
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Dziobek-Garrett R, Imperiale CJ, Wilson MWB, Kempa TJ. Photon Upconversion in a Vapor Deposited 2D Inorganic-Organic Semiconductor Heterostructure. NANO LETTERS 2023. [PMID: 37191568 DOI: 10.1021/acs.nanolett.3c00380] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Energy transfer processes may be engineered in van der Waals heterostructures by taking advantage of the atomically abrupt, Å-scale, and topologically tailorable interfaces within them. Here, we prepare heterostructures comprised of 2D WSe2 monolayers interfaced with dibenzotetraphenylperiflanthene (DBP)-doped rubrene, an organic semiconductor capable of triplet fusion. We fabricate these heterostructures entirely through vapor deposition methods. Time-resolved and steady-state photoluminescence measurements reveal rapid subnanosecond quenching of WSe2 emission by rubrene and fluorescence from guest DBP molecules at 612 nm (λexc = 730 nm), thus providing clear evidence of photon upconversion. The dependence of the upconversion emission on excitation intensity is consistent with a triplet fusion mechanism, and maximum efficiency (linear regime) of this process occurs at threshold intensities as low as 110 mW/cm2, which is comparable to the integrated solar irradiance. This study highlights the potential for advanced optoelectronic applications employing vdWHs which leverage strongly bound excitons in monolayer TMDs and organic semiconductors.
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Affiliation(s)
| | | | - Mark W B Wilson
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Thomas J Kempa
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
- Department of Materials Science & Engineering, Johns Hopkins University, Baltimore, Maryland 21218, United States
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36
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Kenaz R, Ghosh S, Ramachandran P, Watanabe K, Taniguchi T, Steinberg H, Rapaport R. Thickness Mapping and Layer Number Identification of Exfoliated van der Waals Materials by Fourier Imaging Micro-Ellipsometry. ACS NANO 2023; 17:9188-9196. [PMID: 37155829 DOI: 10.1021/acsnano.2c12773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
As performance of van der Waals heterostructure devices is governed by the nanoscale thicknesses and homogeneity of their constituent mono- to few-layer flakes, accurate mapping of these properties with high lateral resolution becomes imperative. Spectroscopic ellipsometry is a promising optical technique for such atomically thin-film characterization due to its simplicity, noninvasive nature and high accuracy. However, the effective use of standard ellipsometry methods on exfoliated micron-scale flakes is inhibited by their tens-of-microns lateral resolution or slow data acquisition. In this work, we demonstrate a Fourier imaging spectroscopic micro-ellipsometry method with sub-5 μm lateral resolution and three orders-of-magnitude faster data acquisition than similar-resolution ellipsometers. Simultaneous recording of spectroscopic ellipsometry information at multiple angles results in a highly sensitive system, which is used for performing angstrom-level accurate and consistent thickness mapping on exfoliated mono-, bi- and trilayers of graphene, hexagonal boron nitride (hBN) and transition metal dichalcogenide (MoS2, WS2, MoSe2, WSe2) flakes. The system can successfully identify highly transparent monolayer hBN, a challenging proposition for other characterization tools. The optical microscope integrated ellipsometer can also map minute thickness variations over a micron-scale flake, revealing its lateral inhomogeneity. The prospect of adding standard optical elements to augment generic optical imaging and spectroscopy setups with accurate in situ ellipsometric mapping capability presents potential opportunities for investigation of exfoliated 2D materials.
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Affiliation(s)
- Ralfy Kenaz
- Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Saptarshi Ghosh
- Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Pradheesh Ramachandran
- Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - 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
| | - Hadar Steinberg
- Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Ronen Rapaport
- Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
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37
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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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38
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Sethi G, Cuma M, Liu F. Excitonic Condensate in Flat Valence and Conduction Bands of Opposite Chirality. PHYSICAL REVIEW LETTERS 2023; 130:186401. [PMID: 37204894 DOI: 10.1103/physrevlett.130.186401] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Revised: 07/01/2022] [Accepted: 04/14/2023] [Indexed: 05/21/2023]
Abstract
Excitonic Bose-Einstein condensation (EBEC) has drawn increasing attention recently with the emergence of 2D materials. A general criterion for EBEC, as expected in an excitonic insulator (EI) state, is to have negative exciton formation energies in a semiconductor. Here, using exact diagonalization of a multiexciton Hamiltonian modeled in a diatomic kagome lattice, we demonstrate that the negative exciton formation energies are only a prerequisite but insufficient condition for realizing an EI. By a comparative study between the cases of both conduction and valence flat bands (FBs) versus that of a parabolic conduction band, we further show that the presence and increased FB contribution to exciton formation provide an attractive avenue to stabilize the excitonic condensate, as confirmed by calculations and analyses of multiexciton energies, wave functions, and reduced density matrices. Our results warrant a similar many-exciton analysis for other known and/or new candidates of EIs and demonstrate the FBs of opposite parity as a unique platform for studying exciton physics, paving the way to material realization of spinor BEC and spin superfluidity.
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Affiliation(s)
- Gurjyot Sethi
- Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, USA
| | - Martin Cuma
- Center for High Performance Computing, University of Utah, Salt Lake City, Utah 84112, USA
| | - Feng Liu
- Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, USA
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39
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Rijal K, Amos S, Valencia-Acuna P, Rudayni F, Fuller N, Zhao H, Peelaers H, Chan WL. Nanoscale Periodic Trapping Sites for Interlayer Excitons Built by Deformable Molecular Crystal on 2D Crystal. ACS NANO 2023; 17:7775-7786. [PMID: 37042658 DOI: 10.1021/acsnano.3c00541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
The nanoscale moiré pattern formed at 2D transition-metal dichalcogenide crystal (TMDC) heterostructures provides periodic trapping sites for excitons, which is essential for realizing various exotic phases such as artificial exciton lattices, Bose-Einstein condensates, and exciton insulators. At organic molecule/TMDC heterostructures, similar periodic potentials can be formed via other degrees of freedom. Here, we utilize the structure deformability of a 2D molecular crystal as a degree of freedom to create a periodic nanoscale potential that can trap interlayer excitons (IXs). Specifically, two semiconducting molecules, PTCDI and PTCDA, which possess similar band gaps and ionization potentials but form different lattice structures on MoS2, are investigated. The PTCDI lattice on MoS2 is distorted geometrically, which lifts the degeneracy of the two molecules within the crystal's unit cell. The degeneracy lifting results in a spatial variation of the molecular orbital energy, with an amplitude and periodicity of ∼0.2 eV and ∼2 nm, respectively. On the other hand, no such energy variation is observed in PTCDA/MoS2, where the PTCDA lattice is much less distorted. The periodic variation in molecular orbital energies provides effective trapping sites for IXs. For IXs formed at PTCDI/MoS2, rapid spatial localization of the electron in the organic layer toward the interface is observed, which demonstrates the effectiveness of these interfacial IX traps.
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Affiliation(s)
- Kushal Rijal
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
| | - Stephanie Amos
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
| | - Pavel Valencia-Acuna
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
| | - Fatimah Rudayni
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
- Department of Physics, Jazan University, Jazan 45142, Saudi Arabia
| | - Neno Fuller
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
| | - Hui Zhao
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
| | - Hartwin Peelaers
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
| | - Wai-Lun Chan
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
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40
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Guo X, Lyu W, Chen T, Luo Y, Wu C, Yang B, Sun Z, García de Abajo FJ, Yang X, Dai Q. Polaritons in Van der Waals Heterostructures. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2201856. [PMID: 36121344 DOI: 10.1002/adma.202201856] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Revised: 08/15/2022] [Indexed: 05/17/2023]
Abstract
2D monolayers supporting a wide variety of highly confined plasmons, phonon polaritons, and exciton polaritons can be vertically stacked in van der Waals heterostructures (vdWHs) with controlled constituent layers, stacking sequence, and even twist angles. vdWHs combine advantages of 2D material polaritons, rich optical structure design, and atomic scale integration, which have greatly extended the performance and functions of polaritons, such as wide frequency range, long lifetime, ultrafast all-optical modulation, and photonic crystals for nanoscale light. Here, the state of the art of 2D material polaritons in vdWHs from the perspective of design principles and potential applications is reviewed. Some fundamental properties of polaritons in vdWHs are initially discussed, followed by recent discoveries of plasmons, phonon polaritons, exciton polaritons, and their hybrid modes in vdWHs. The review concludes with a perspective discussion on potential applications of these polaritons such as nanophotonic integrated circuits, which will benefit from the intersection between nanophotonics and materials science.
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Affiliation(s)
- Xiangdong Guo
- CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Wei Lyu
- CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Tinghan Chen
- CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- School of Life Science, Peking University, Beijing, 100871, P. R. China
| | - Yang Luo
- CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- School of Life Science, Peking University, Beijing, 100871, P. R. China
| | - Chenchen Wu
- CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Bei Yang
- CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Zhipei Sun
- Department of Electronics and Nanoengineering and QTF Centre of Excellence, Department of Applied Physics, Aalto University, Espoo, 02150, Finland
| | - F Javier García de Abajo
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Barcelona, 08860, Spain
- ICREA-Institució Catalana de Recerca i Estudis Avançats, Passeig Lluís Companys 23, Barcelona, 08010, Spain
| | - Xiaoxia Yang
- CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Qing Dai
- CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
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41
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Park S, Kim D, Choi YS, Baucour A, Kim D, Yoon S, Watanabe K, Taniguchi T, Shin J, Kim J, Seo MK. Customizing Radiative Decay Dynamics of Two-Dimensional Excitons via Position- and Polarization-Dependent Vacuum-Field Interference. NANO LETTERS 2023; 23:2158-2165. [PMID: 36854053 DOI: 10.1021/acs.nanolett.2c04604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Embodying bosonic and interactive characteristics in two-dimensional space, excitons in transition metal dichalcogenides (TMDCs) have garnered considerable attention. The utilization of the strong-correlation effects, long-range transport, and valley-dependent properties requires customizing exciton decay dynamics. Vacuum-field manipulation allows radiative decay engineering without disturbing intrinsic material properties. However, conventional flat mirrors cannot customize the radiative decay landscape in TMDC's plane or support vacuum-field interference with desired spectrum and polarization properties. Here, we present a meta-mirror platform resolving the issues with more optical degrees of freedom. For neutral excitons of the monolayer MoSe2, the optical layout formed by meta-mirrors manipulated the radiative decay rate in space by 2 orders of magnitude and revealed the statistical correlation between emission intensity and spectral line width. Moreover, the anisotropic meta-mirror demonstrated polarization-dependent radiative decay control. Our platform would be promising to tailor two-dimensional distributions of lifetime, density, diffusion, and polarization of TMDC excitons in advanced opto-excitonic applications.
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Affiliation(s)
- Sanghyeok Park
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Dongha Kim
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Yun-Seok Choi
- Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Arthur Baucour
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Donghyeong Kim
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Sangho Yoon
- Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
- Center for van der Waals Quantum Solids, Institute for Basic Science (IBS), Pohang 37673, Republic of Korea
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba 305-0044, Japan
| | - Jonghwa Shin
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Jonghwan Kim
- Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
- Center for van der Waals Quantum Solids, Institute for Basic Science (IBS), Pohang 37673, Republic of Korea
| | - Min-Kyo Seo
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
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42
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Tang L, Mao Z, Wang C, Fu Q, Wang C, Zhang Y, Shen J, Yin Y, Shen B, Tan D, Li Q, Wang Y, Medhekar NV, Wu J, Yuan H, Li Y, Fuhrer MS, Zheng C. Giant piezoresistivity in a van der Waals material induced by intralayer atomic motions. Nat Commun 2023; 14:1519. [PMID: 36934098 PMCID: PMC10024745 DOI: 10.1038/s41467-023-37239-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 03/07/2023] [Indexed: 03/20/2023] Open
Abstract
The presence of the van der Waals gap in layered materials creates a wealth of intriguing phenomena different to their counterparts in conventional materials. For example, pressurization can generate a large anisotropic lattice shrinkage along the stacking orientation and/or a significant interlayer sliding, and many of the exotic pressure-dependent properties derive from these mechanisms. Here we report a giant piezoresistivity in pressurized β'-In2Se3. Upon compression, a six-orders-of-magnitude drop of electrical resistivity is obtained below 1.2 GPa in β'-In2Se3 flakes, yielding a giant piezoresistive gauge πp of -5.33 GPa-1. Simultaneously, the sample undergoes a semiconductor-to-semimetal transition without a structural phase transition. Surprisingly, linear dichroism study and theoretical first principles modelling show that these phenomena arise not due to shrinkage or sliding at the van der Waals gap, but rather are dominated by the layer-dependent atomic motions inside the quintuple layer, mainly from the shifting of middle Se atoms to their high-symmetric location. The atomic motions link to both the band structure modulation and the in-plane ferroelectric dipoles. Our work not only provides a prominent piezoresistive material but also points out the importance of intralayer atomic motions beyond van der Waals gap.
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Affiliation(s)
- Lingyun Tang
- School of Physics and Optoelectronics, South China University of Technology, Guangzhou, Guangdong, 510641, China
| | - Zhongquan Mao
- School of Physics and Optoelectronics, South China University of Technology, Guangzhou, Guangdong, 510641, China
| | - Chutian Wang
- Department of Materials Science and Engineering, & ARC Centre of Excellence in Future Low Energy Electronics Technologies, Monash University, Clayton, VIC, Australia
| | - Qi Fu
- Key Laboratory for Quantum Materials of Zhejiang Province, School of Science, Westlake University, Hangzhou, 310024, Zhejiang Province, China
| | - Chen Wang
- Key Laboratory for Quantum Materials of Zhejiang Province, School of Science, Westlake University, Hangzhou, 310024, Zhejiang Province, China
| | - Yichi Zhang
- Key Laboratory for Quantum Materials of Zhejiang Province, School of Science, Westlake University, Hangzhou, 310024, Zhejiang Province, China
| | - Jingyi Shen
- Key Laboratory for Quantum Materials of Zhejiang Province, School of Science, Westlake University, Hangzhou, 310024, Zhejiang Province, China
| | - Yuefeng Yin
- Department of Materials Science and Engineering, & ARC Centre of Excellence in Future Low Energy Electronics Technologies, Monash University, Clayton, VIC, Australia
| | - Bin Shen
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou, China
| | - Dayong Tan
- Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 510640, Guangzhou, Guangdong, China
| | - Qian Li
- Shandong Key Laboratory of Optical Communication Science and Technology, School of Physics Science and Information Technology, Liaocheng University, Liaocheng, 252000, China
| | - Yonggang Wang
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), Beijing, 100094, China
| | - Nikhil V Medhekar
- Department of Materials Science and Engineering, & ARC Centre of Excellence in Future Low Energy Electronics Technologies, Monash University, Clayton, VIC, Australia
| | - Jie Wu
- Key Laboratory for Quantum Materials of Zhejiang Province, School of Science, Westlake University, Hangzhou, 310024, Zhejiang Province, China
| | - Huiqiu Yuan
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou, China
| | - Yanchun Li
- Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China.
| | - Michael S Fuhrer
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies, & School of Physics and Astronomy, Monash University, Melbourne, VIC, 3800, Australia.
| | - Changxi Zheng
- Key Laboratory for Quantum Materials of Zhejiang Province, School of Science, Westlake University, Hangzhou, 310024, Zhejiang Province, China.
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43
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Xiao C, Wang Y, Yao W. Dynamic Generation of Spin Spirals of Moiré Trapped Carriers via Exciton Mediated Spin Interactions. NANO LETTERS 2023; 23:1872-1877. [PMID: 36799955 DOI: 10.1021/acs.nanolett.2c04816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Stacking transition metal dichalcogenides (TMDs) to form moiré superlattices has provided exciting opportunities to explore many-body correlation phenomena of the moiré trapped carriers. TMD bilayers, on the other hand, host long-lived interlayer exciton (IX), an elementary excitation of long spin-valley lifetime that can be optically or electrically injected. Here we find that, through the Coulomb exchange between mobile IXs and carriers, the IX bath can mediate both Heisenberg and Dzyaloshinskii-Moriya type spin interactions between moiré trapped carriers, controllable by exciton density and exciton spin current, respectively. We show the strong Heisenberg interaction and the extraordinarily long-ranged Dzyaloshinskii-Moriya interaction here can jointly establish robust spin spiral magnetic orders in Mott-Wigner crystal states at various filling factors, with the spiral direction controlled by the exciton current.
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Affiliation(s)
- Chengxin Xiao
- Department of Physics, The University of Hong Kong, Hong Kong, China
- HKU-UCAS Joint Institute of Theoretical and Computational Physics at Hong Kong, Hong Kong, China
| | - Yong Wang
- School of Physics, Nankai University, Tianjin 300071, China
- Department of Physics, The University of Hong Kong, Hong Kong, Hong Kong, China
| | - Wang Yao
- Department of Physics, The University of Hong Kong, Hong Kong, China
- HKU-UCAS Joint Institute of Theoretical and Computational Physics at Hong Kong, Hong Kong, China
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44
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Koo Y, Lee H, Ivanova T, Kefayati A, Perebeinos V, Khestanova E, Kravtsov V, Park KD. Tunable interlayer excitons and switchable interlayer trions via dynamic near-field cavity. LIGHT, SCIENCE & APPLICATIONS 2023; 12:59. [PMID: 36864035 PMCID: PMC9981773 DOI: 10.1038/s41377-023-01087-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 01/07/2023] [Accepted: 02/01/2023] [Indexed: 06/18/2023]
Abstract
Emerging photo-induced excitonic processes in transition metal dichalcogenide (TMD) heterobilayers, e.g., interplay of intra- and inter-layer excitons and conversion of excitons to trions, allow new opportunities for ultrathin hybrid photonic devices. However, with the associated large degree of spatial heterogeneity, understanding and controlling their complex competing interactions in TMD heterobilayers at the nanoscale remains a challenge. Here, we present an all-round dynamic control of interlayer-excitons and -trions in a WSe2/Mo0.5 W0.5 Se2 heterobilayer using multifunctional tip-enhanced photoluminescence (TEPL) spectroscopy with <20 nm spatial resolution. Specifically, we demonstrate the bandgap tunable interlayer excitons and the dynamic interconversion between interlayer-trions and -excitons, through the combinational tip-induced engineering of GPa-scale pressure and plasmonic hot electron injection, with simultaneous spectroscopic TEPL measurements. This unique nano-opto-electro-mechanical control approach provides new strategies for developing versatile nano-excitonic/trionic devices using TMD heterobilayers.
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Affiliation(s)
- Yeonjeong Koo
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Hyeongwoo Lee
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Tatiana Ivanova
- School of Physics and Engineering, ITMO University, Saint Petersburg, 197101, Russia
| | - Ali Kefayati
- Department of Electrical Engineering, University at Buffalo, New York, NY, 14260, USA
| | - Vasili Perebeinos
- Department of Electrical Engineering, University at Buffalo, New York, NY, 14260, USA
| | - Ekaterina Khestanova
- School of Physics and Engineering, ITMO University, Saint Petersburg, 197101, Russia
| | - Vasily Kravtsov
- School of Physics and Engineering, ITMO University, Saint Petersburg, 197101, Russia.
| | - Kyoung-Duck Park
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea.
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45
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Evidence of high-temperature exciton condensation in a two-dimensional semimetal. Nat Commun 2023; 14:994. [PMID: 36813811 PMCID: PMC9946959 DOI: 10.1038/s41467-023-36667-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 02/07/2023] [Indexed: 02/24/2023] Open
Abstract
Electrons and holes can spontaneously form excitons and condense in a semimetal or semiconductor, as predicted decades ago. This type of Bose condensation can happen at much higher temperatures in comparison with dilute atomic gases. Two-dimensional (2D) materials with reduced Coulomb screening around the Fermi level are promising for realizing such a system. Here we report a change in the band structure accompanied by a phase transition at about 180 K in single-layer ZrTe2 based on angle-resolved photoemission spectroscopy (ARPES) measurements. Below the transition temperature, gap opening and development of an ultra-flat band top around the zone center are observed. This gap and the phase transition are rapidly suppressed with extra carrier densities introduced by adding more layers or dopants on the surface. The results suggest the formation of an excitonic insulating ground state in single-layer ZrTe2, and the findings are rationalized by first-principles calculations and a self-consistent mean-field theory. Our study provides evidence for exciton condensation in a 2D semimetal and demonstrates strong dimensionality effects on the formation of intrinsic bound electron-hole pairs in solids.
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46
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Yoon Y, Zhang Z, Qi R, Joe AY, Sailus R, Watanabe K, Taniguchi T, Tongay S, Wang F. Charge Transfer Dynamics in MoSe 2/hBN/WSe 2 Heterostructures. NANO LETTERS 2022; 22:10140-10146. [PMID: 36485010 DOI: 10.1021/acs.nanolett.2c04030] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Ultrafast charge transfer processes provide a facile way to create interlayer excitons in directly contacted transition metal dichalcogenide (TMD) layers. More sophisticated heterostructures composed of TMD/hBN/TMD enable new ways to control interlayer exciton properties and achieve novel exciton phenomena, such as exciton insulators and condensates, where longer lifetimes are desired. In this work, we experimentally study the charge transfer dynamics in a heterostructure composed of a 1 nm thick hBN spacer between MoSe2 and WSe2 monolayers. We observe the hole transfer from MoSe2 to WSe2 through the hBN barrier with a time constant of 500 ps, which is over 3 orders of magnitude slower than that between TMD layers without a spacer. Furthermore, we observe strong competition between the interlayer charge transfer and intralayer exciton-exciton annihilation processes at high excitation densities. Our work opens possibilities to understand charge transfer pathways in TMD/hBN/TMD heterostructures for the efficient generation and control of interlayer excitons.
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Affiliation(s)
- Yoseob Yoon
- Department of Physics, University of California, Berkeley, California94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
| | - Zuocheng Zhang
- Department of Physics, University of California, Berkeley, California94720, United States
| | - Ruishi Qi
- Department of Physics, University of California, Berkeley, California94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
| | - Andrew Y Joe
- Department of Physics, University of California, Berkeley, California94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
| | - Renee Sailus
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona85287, United States
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba305-0044, Japan
| | - Sefaattin Tongay
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona85287, United States
| | - Feng Wang
- Department of Physics, University of California, Berkeley, California94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
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47
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Lei Y, Zhang T, Lin YC, Granzier-Nakajima T, Bepete G, Kowalczyk DA, Lin Z, Zhou D, Schranghamer TF, Dodda A, Sebastian A, Chen Y, Liu Y, Pourtois G, Kempa TJ, Schuler B, Edmonds MT, Quek SY, Wurstbauer U, Wu SM, Glavin NR, Das S, Dash SP, Redwing JM, Robinson JA, Terrones M. Graphene and Beyond: Recent Advances in Two-Dimensional Materials Synthesis, Properties, and Devices. ACS NANOSCIENCE AU 2022; 2:450-485. [PMID: 36573124 PMCID: PMC9782807 DOI: 10.1021/acsnanoscienceau.2c00017] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 08/22/2022] [Accepted: 08/23/2022] [Indexed: 12/30/2022]
Abstract
Since the isolation of graphene in 2004, two-dimensional (2D) materials research has rapidly evolved into an entire subdiscipline in the physical sciences with a wide range of emergent applications. The unique 2D structure offers an open canvas to tailor and functionalize 2D materials through layer number, defects, morphology, moiré pattern, strain, and other control knobs. Through this review, we aim to highlight the most recent discoveries in the following topics: theory-guided synthesis for enhanced control of 2D morphologies, quality, yield, as well as insights toward novel 2D materials; defect engineering to control and understand the role of various defects, including in situ and ex situ methods; and properties and applications that are related to moiré engineering, strain engineering, and artificial intelligence. Finally, we also provide our perspective on the challenges and opportunities in this fascinating field.
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Affiliation(s)
- Yu Lei
- Department
of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Center
for Atomically Thin Multifunctional Coatings, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Institute
of Materials Research, Tsinghua Shenzhen
International Graduate School, Shenzhen, Guangdong 518055, China,Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Tianyi Zhang
- Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Department
of Material Science and Engineering, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Yu-Chuan Lin
- Center
for Atomically Thin Multifunctional Coatings, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Department
of Material Science and Engineering, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Tomotaroh Granzier-Nakajima
- Department
of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - George Bepete
- Department
of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Center
for Atomically Thin Multifunctional Coatings, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Dorota A. Kowalczyk
- Department
of Solid State Physics, Faculty of Physics and Applied Informatics, University of Lodz, Pomorska 149/153, Lodz 90-236, Poland
| | - Zhong Lin
- Department
of Physics, University of Washington, Seattle, Washington 98195, United States
| | - Da Zhou
- Department
of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Thomas F. Schranghamer
- Department
of Engineering Science and Mechanics, Pennsylvania
State University, University Park, Pennsylvania 16802, United States
| | - Akhil Dodda
- Department
of Engineering Science and Mechanics, Pennsylvania
State University, University Park, Pennsylvania 16802, United States
| | - Amritanand Sebastian
- Department
of Engineering Science and Mechanics, Pennsylvania
State University, University Park, Pennsylvania 16802, United States
| | - Yifeng Chen
- Department
of Materials Science and Engineering, National
University of Singapore, 9 Engineering Drive, Singapore 117456, Singapore
| | - Yuanyue Liu
- Texas
Materials Institute and Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | | | - Thomas J. Kempa
- Department
of Chemistry, Johns Hopkins University, Baltimore, Maryland 21287, United States
| | - Bruno Schuler
- nanotech@surfaces
Laboratory, Empa − Swiss Federal
Laboratories for Materials Science and Technology, Dübendorf 8600, Switzerland
| | - Mark T. Edmonds
- School
of Physics and Astronomy, Monash University, Clayton, Victoria 3800, Australia
| | - Su Ying Quek
- Department
of Materials Science and Engineering, National
University of Singapore, 9 Engineering Drive, Singapore 117456, Singapore
| | - Ursula Wurstbauer
- Institute
of Physics, University of Münster, Wilhelm-Klemm-Str. 10, Münster 48149, Germany
| | - Stephen M. Wu
- Department
of Electrical and Computer Engineering & Department of Physics
and Astronomy, University of Rochester, Rochester, New York 14627, United States
| | - Nicholas R. Glavin
- Air
Force
Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson AFB, Dayton, Ohio 45433, United States
| | - Saptarshi Das
- Center
for Atomically Thin Multifunctional Coatings, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Department
of Material Science and Engineering, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States,Department
of Engineering Science and Mechanics, Pennsylvania
State University, University Park, Pennsylvania 16802, United States
| | - Saroj Prasad Dash
- Department
of Microtechnology and Nanoscience, Chalmers
University of Technology, Göteborg SE-412 96, Sweden
| | - Joan M. Redwing
- Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Department
of Material Science and Engineering, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Joshua A. Robinson
- Center
for Atomically Thin Multifunctional Coatings, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Department
of Material Science and Engineering, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States,
| | - Mauricio Terrones
- Department
of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Center
for Atomically Thin Multifunctional Coatings, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Department
of Material Science and Engineering, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States,Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Research
Initiative for Supra-Materials and Global Aqua Innovation Center, Shinshu University, 4-17-1Wakasato, Nagano 380-8553, Japan,
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48
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Di Renzo A, Çakıroğlu O, Carrascoso F, Li H, Gigli G, Watanabe K, Taniguchi T, Munuera C, Rizzo A, Castellanos-Gomez A, Mastria R, Frisenda R. Enhanced Field-Effect Control of Single-Layer WS 2 Optical Features by hBN Full Encapsulation. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:4425. [PMID: 36558278 PMCID: PMC9788429 DOI: 10.3390/nano12244425] [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: 11/14/2022] [Revised: 11/30/2022] [Accepted: 12/08/2022] [Indexed: 06/17/2023]
Abstract
The field-effect control of the electrical and optical properties of two-dimensional (2D) van der Waals semiconductors (vdW) is one important aspect of this novel class of materials. Thanks to their reduced thickness and decreased screening, electric fields can easily penetrate in a 2D semiconductor and thus modulate their charge density and their properties. In literature, the field effect is routinely used to fabricate atomically thin field-effect transistors based on 2D semiconductors. Apart from the tuning of the electrical transport, it has been demonstrated that the field effect can also be used to modulate the excitonic optical emission of 2D transition metal dichalcogenides such as MoS2 or WSe2. In this paper, we present some recent experiments on the field-effect control of the optical and excitonic properties of the monolayer WS2. Using the deterministic transfer of van der Waals materials, we fabricate planar single-layer WS2 devices contacted by a gold electrode and partially sandwiched between two insulating hexagonal boron nitride (hBN) flakes. Thanks to the planar nature of the device, we can optically access both the hBN encapsulated and the unencapsulated WS2 regions and compare the field-effect control of the exciton population in the two cases. We find that the encapsulation strongly increases the range of tunability of the optical emission of WS2, allowing us to tune the photoluminescence emission from excitons-dominated to trions-dominated. We also discuss how the full encapsulation of WS2 with hBN helps reduce spurious hysteretic effects in the field-effect control of the optical properties, similar to what has been reported for 2D vdW field-effect transistors.
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Affiliation(s)
- Anna Di Renzo
- Department of Mathematics and Physics “Ennio De Giorgi”, University of Salento, Via Arnesano, 73100 Lecce, Italy
- National Research Council, Institute of Nanotechnology (CNR-NANOTEC), Via Monteroni, 73100 Lecce, Italy
| | - Onur Çakıroğlu
- Materials Science Factory, Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), E-28049 Madrid, Spain
| | - Felix Carrascoso
- Materials Science Factory, Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), E-28049 Madrid, Spain
| | - Hao Li
- Materials Science Factory, Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), E-28049 Madrid, Spain
| | - Giuseppe Gigli
- Department of Mathematics and Physics “Ennio De Giorgi”, University of Salento, Via Arnesano, 73100 Lecce, Italy
- National Research Council, Institute of Nanotechnology (CNR-NANOTEC), Via Monteroni, 73100 Lecce, Italy
| | - 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
| | - Carmen Munuera
- Materials Science Factory, Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), E-28049 Madrid, Spain
| | - Aurora Rizzo
- National Research Council, Institute of Nanotechnology (CNR-NANOTEC), Via Monteroni, 73100 Lecce, Italy
| | - Andres Castellanos-Gomez
- Materials Science Factory, Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), E-28049 Madrid, Spain
| | - Rosanna Mastria
- National Research Council, Institute of Nanotechnology (CNR-NANOTEC), Via Monteroni, 73100 Lecce, Italy
| | - Riccardo Frisenda
- Materials Science Factory, Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), E-28049 Madrid, Spain
- Physics Department, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
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49
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Strain control of hybridization between dark and localized excitons in a 2D semiconductor. Nat Commun 2022; 13:7691. [PMID: 36509779 PMCID: PMC9744834 DOI: 10.1038/s41467-022-35352-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 11/30/2022] [Indexed: 12/14/2022] Open
Abstract
Mechanical strain is a powerful tuning knob for excitons, Coulomb-bound electron-hole complexes dominating optical properties of two-dimensional semiconductors. While the strain response of bright free excitons is broadly understood, the behaviour of dark free excitons (long-lived excitations that generally do not couple to light due to spin and momentum conservation) or localized excitons related to defects remains mostly unexplored. Here, we study the strain behaviour of these fragile many-body states on pristine suspended WSe2 kept at cryogenic temperatures. We find that under the application of strain, dark and localized excitons in monolayer WSe2-a prototypical 2D semiconductor-are brought into energetic resonance, forming a new hybrid state that inherits the properties of the constituent species. The characteristics of the hybridized state, including an order-of-magnitude enhanced light/matter coupling, avoided-crossing energy shifts, and strain tunability of many-body interactions, are all supported by first-principles calculations. The hybridized excitons reported here may play a critical role in the operation of single quantum emitters based on WSe2. Furthermore, the techniques we developed may be used to fingerprint unidentified excitonic states.
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50
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Tan Q, Rasmita A, Zhang Z, Novoselov KS, Gao WB. Signature of Cascade Transitions between Interlayer Excitons in a Moiré Superlattice. PHYSICAL REVIEW LETTERS 2022; 129:247401. [PMID: 36563256 DOI: 10.1103/physrevlett.129.247401] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Accepted: 11/08/2022] [Indexed: 06/17/2023]
Abstract
A moiré superlattice in transition metal dichalcogenides heterostructure provides an exciting platform for studying strongly correlated electronics and excitonic physics, such as multiple interlayer exciton (IX) energy bands. However, the correlations between these IXs remain elusive. Here, we demonstrate the cascade transitions between IXs in a moiré superlattice by performing energy- and time-resolved photoluminescence measurements in the MoS_{2}/WSe_{2} heterostructure. Furthermore, we show that the lower-energy IX can be excited to higher-energy ones, facilitating IX population inversion. Our finding of cascade transitions between IXs contributes to the fundamental understanding of the IX dynamics in moiré superlattices and may have important applications, such as in exciton condensate, quantum information protocols, and quantum cascade lasers.
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Affiliation(s)
- Qinghai Tan
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- The Photonics Institute and Centre for Disruptive Photonic Technologies, Nanyang Technological University, Singapore 637371, Singapore
| | - Abdullah Rasmita
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Zhaowei Zhang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - K S Novoselov
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, 117575, Singapore
| | - Wei-Bo Gao
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- The Photonics Institute and Centre for Disruptive Photonic Technologies, Nanyang Technological University, Singapore 637371, Singapore
- Centre for Quantum Technologies, National University of Singapore, 117543 Singapore, Singapore
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