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Mujeeb F, Rana G, Chakrabarti P, Prasad Sahu B, Jeena R, Datta A, Dhar S. Recombination dynamics and manybody effect of excitons in large-area monolayer MoS 2capped with (111) NiO epitaxial layer. J Phys Condens Matter 2024; 36:315003. [PMID: 38657634 DOI: 10.1088/1361-648x/ad42f0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Accepted: 04/24/2024] [Indexed: 04/26/2024]
Abstract
CVD grown monolayer MoS2films on c-sapphire substrates are vacuum annealed and capped with (111) NiO epitaxial films using pulsed laser deposition technique. Time, energy and polarization resolved optical techniques are used to understand the effect of capping on the excitonic properties of the monolayer MoS2. It has been observed that trion contribution in the photoluminescence (PL) spectra increases after the capping, suggesting an enhancement of electron concentration in the conduction band. This has been attributed to the capping driven reduction of physisorbed air molecules from the sulphur vacancy (VS) sites. Note that the air molecules act as passivating agents for theVS-donors. Low temperature polarization resolved PL spectroscopy and ultrafast pump and probe transient absorption spectroscopy (TAS) show an increase of the biexcitonic population in the system after the encapsulation. The TAS study further reveals longer lifetime for both A and B excitons in capped samples implying a reduction of non-radiative recombination rate of the excitons after the capping. It has also been observed that in the capped samples,K/K'valleys are populated with trions under sufficiently high pump powers. This has been attributed to the lower non-radiative recombination rates of the high energy photoexcited carriers and the faster transfer of either electrons or holes from the high energy pockets to theK/K'valleys. The study further reveals different many-body effects in excitons and trions.
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Affiliation(s)
- Faiha Mujeeb
- Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Gourab Rana
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Poulab Chakrabarti
- Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Bhabani Prasad Sahu
- Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Rupa Jeena
- Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Anindya Datta
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Subhabrata Dhar
- Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076, India
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2
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Yang H, Hu R, Wu H, He X, Zhou Y, Xue Y, He K, Hu W, Chen H, Gong M, Zhang X, Tan PH, Hernández ER, Xie Y. Identification and Structural Characterization of Twisted Atomically Thin Bilayer Materials by Deep Learning. Nano Lett 2024; 24:2789-2797. [PMID: 38407030 PMCID: PMC10921996 DOI: 10.1021/acs.nanolett.3c04815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 02/19/2024] [Accepted: 02/20/2024] [Indexed: 02/27/2024]
Abstract
Two-dimensional materials are expected to play an important role in next-generation electronics and optoelectronic devices. Recently, twisted bilayer graphene and transition metal dichalcogenides have attracted significant attention due to their unique physical properties and potential applications. In this study, we describe the use of optical microscopy to collect the color space of chemical vapor deposition (CVD) of molybdenum disulfide (MoS2) and the application of a semantic segmentation convolutional neural network (CNN) to accurately and rapidly identify thicknesses of MoS2 flakes. A second CNN model is trained to provide precise predictions on the twist angle of CVD-grown bilayer flakes. This model harnessed a data set comprising over 10,000 synthetic images, encompassing geometries spanning from hexagonal to triangular shapes. Subsequent validation of the deep learning predictions on twist angles was executed through the second harmonic generation and Raman spectroscopy. Our results introduce a scalable methodology for automated inspection of twisted atomically thin CVD-grown bilayers.
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Affiliation(s)
- Haitao Yang
- Key
Laboratory of Wide Band-Gap Semiconductor Technology & Shaanxi
Key Laboratory of High-Orbits-Electron Materials and Protection Technology
for Aerospace, School of Advanced Materials and Nanotechnology, Xidian University, Xi’an 710071, China
| | - Ruiqi Hu
- Department
of Materials Science and Engineering, University
of Delaware, Newark, Delaware 19716, United States
| | - Heng Wu
- State
Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Xiaolong He
- Key
Laboratory of Wide Band-Gap Semiconductor Technology & Shaanxi
Key Laboratory of High-Orbits-Electron Materials and Protection Technology
for Aerospace, School of Advanced Materials and Nanotechnology, Xidian University, Xi’an 710071, China
| | - Yan Zhou
- State
Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- Phonon
Engineering Research Center of Jiangsu Province, School of Physics
and Technology, Nanjing Normal University, Nanjing 210023, China
| | - Yizhe Xue
- Key
Laboratory of Wide Band-Gap Semiconductor Technology & Shaanxi
Key Laboratory of High-Orbits-Electron Materials and Protection Technology
for Aerospace, School of Advanced Materials and Nanotechnology, Xidian University, Xi’an 710071, China
| | - Kexin He
- Key
Laboratory of Wide Band-Gap Semiconductor Technology & Shaanxi
Key Laboratory of High-Orbits-Electron Materials and Protection Technology
for Aerospace, School of Advanced Materials and Nanotechnology, Xidian University, Xi’an 710071, China
| | - Wenshuai Hu
- Key
Laboratory of Wide Band-Gap Semiconductor Technology & Shaanxi
Key Laboratory of High-Orbits-Electron Materials and Protection Technology
for Aerospace, School of Advanced Materials and Nanotechnology, Xidian University, Xi’an 710071, China
| | - Haosen Chen
- Key
Laboratory of Wide Band-Gap Semiconductor Technology & Shaanxi
Key Laboratory of High-Orbits-Electron Materials and Protection Technology
for Aerospace, School of Advanced Materials and Nanotechnology, Xidian University, Xi’an 710071, China
| | - Mingming Gong
- School
of Materials Science and Engineering, Northwestern
Polytechnical University, Xi’an 710072, China
| | - Xin Zhang
- State
Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Ping-Heng Tan
- State
Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | | | - Yong Xie
- Key
Laboratory of Wide Band-Gap Semiconductor Technology & Shaanxi
Key Laboratory of High-Orbits-Electron Materials and Protection Technology
for Aerospace, School of Advanced Materials and Nanotechnology, Xidian University, Xi’an 710071, China
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3
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Xu C, Barden N, Alexeev EM, Wang X, Long R, Cadore AR, Paradisanos I, Ott AK, Soavi G, Tongay S, Cerullo G, Ferrari AC, Prezhdo OV, Loh ZH. Ultrafast Charge Transfer and Recombination Dynamics in Monolayer-Multilayer WSe 2 Junctions Revealed by Time-Resolved Photoemission Electron Microscopy. ACS Nano 2024; 18:1931-1947. [PMID: 38197410 DOI: 10.1021/acsnano.3c06473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2024]
Abstract
The ultrafast carrier dynamics of junctions between two chemically identical, but electronically distinct, transition metal dichalcogenides (TMDs) remains largely unknown. Here, we employ time-resolved photoemission electron microscopy (TR-PEEM) to probe the ultrafast carrier dynamics of a monolayer-to-multilayer (1L-ML) WSe2 junction. The TR-PEEM signals recorded for the individual components of the junction reveal the sub-ps carrier cooling dynamics of 1L- and 7L-WSe2, as well as few-ps exciton-exciton annihilation occurring on 1L-WSe2. We observe ultrafast interfacial hole (h) transfer from 1L- to 7L-WSe2 on an ∼0.2 ps time scale. The resultant excess h density in 7L-WSe2 decays by carrier recombination across the junction interface on an ∼100 ps time scale. Reminiscent of the behavior at a depletion region, the TR-PEEM image reveals the h density accumulation on the 7L-WSe2 interface, with a decay length ∼0.60 ± 0.17 μm. These charge transfer and recombination dynamics are in agreement with ab initio quantum dynamics. The computed orbital densities reveal that charge transfer occurs from the basal plane, which extends over both 1L and ML regions, to the upper plane localized on the ML region. This mode of charge transfer is distinctive to chemically homogeneous junctions of layered materials and constitutes an additional carrier deactivation pathway that should be considered in studies of 1L-TMDs found alongside their ML, a common occurrence in exfoliated samples.
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Affiliation(s)
- Ce Xu
- School of Chemistry, Chemical Engineering and Biotechnology, and School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Natalie Barden
- School of Chemistry, Chemical Engineering and Biotechnology, and School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Evgeny M Alexeev
- Cambridge Graphene Centre, University of Cambridge, Cambridge CB3 0FA, U.K
| | - Xiaoli Wang
- College of Chemistry, Key Laboratory of Theoretical and Computational Photochemistry, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Run Long
- College of Chemistry, Key Laboratory of Theoretical and Computational Photochemistry, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Alisson R Cadore
- Cambridge Graphene Centre, University of Cambridge, Cambridge CB3 0FA, U.K
| | | | - Anna K Ott
- Cambridge Graphene Centre, University of Cambridge, Cambridge CB3 0FA, U.K
| | - Giancarlo Soavi
- Cambridge Graphene Centre, University of Cambridge, Cambridge CB3 0FA, U.K
- Institute of Solid State Physics, Friedrich Schiller University Jena, Max-Wien-Platz 1, 07743 Jena, Germany
| | - Sefaattin Tongay
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona 85287, United States
| | - Giulio Cerullo
- Department of Physics, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano, Italy
- IFN-CNR, Piazza Leonardo da Vinci 32, I-20133 Milano, Italy
| | - Andrea C Ferrari
- Cambridge Graphene Centre, University of Cambridge, Cambridge CB3 0FA, U.K
| | - Oleg V Prezhdo
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Zhi-Heng Loh
- School of Chemistry, Chemical Engineering and Biotechnology, and School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
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4
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Bayramov AH, Bagiyev EA, Alizade EH, Jalilli JN, Mamedov NT, Jahangirli ZA, Asadullayeva SG, Aliyeva YN, Cuscunà M, Lorenzo D, Esposito M, Balestra G, Simeone D, Tobaldi DM, Abou-Ras D, Schorr S. Two-Channel Indirect-Gap Photoluminescence and Competition between the Conduction Band Valleys in Few-Layer MoS 2. Nanomaterials (Basel) 2023; 14:96. [PMID: 38202552 PMCID: PMC10780461 DOI: 10.3390/nano14010096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 12/20/2023] [Accepted: 12/22/2023] [Indexed: 01/12/2024]
Abstract
MoS2 is a two-dimensional layered transition metal dichalcogenide with unique electronic and optical properties. The fabrication of ultrathin MoS2 is vitally important, since interlayer interactions in its ultrathin varieties will become thickness-dependent, providing thickness-governed tunability and diverse applications of those properties. Unlike with a number of studies that have reported detailed information on direct bandgap emission from MoS2 monolayers, reliable experimental evidence for thickness-induced evolution or transformation of the indirect bandgap remains scarce. Here, the sulfurization of MoO3 thin films with nominal thicknesses of 30 nm, 5 nm and 3 nm was performed. All sulfurized samples were examined at room temperature with spectroscopic ellipsometry and photoluminescence spectroscopy to obtain information about their dielectric function and edge emission spectra. This investigation unveiled an indirect-to-indirect crossover between the transitions, associated with two different Λ and K valleys of the MoS2 conduction band, by thinning its thickness down to a few layers.
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Affiliation(s)
- Ayaz H. Bayramov
- Institute of Physics, Ministry of Science and Education, Baku Az1143, Azerbaijan; (A.H.B.); (E.H.A.); (S.G.A.)
| | - Elnur A. Bagiyev
- Institute of Physics, Ministry of Science and Education, Baku Az1143, Azerbaijan; (A.H.B.); (E.H.A.); (S.G.A.)
| | - Elvin H. Alizade
- Institute of Physics, Ministry of Science and Education, Baku Az1143, Azerbaijan; (A.H.B.); (E.H.A.); (S.G.A.)
| | - Javid N. Jalilli
- Institute of Physics, Ministry of Science and Education, Baku Az1143, Azerbaijan; (A.H.B.); (E.H.A.); (S.G.A.)
| | - Nazim T. Mamedov
- Institute of Physics, Ministry of Science and Education, Baku Az1143, Azerbaijan; (A.H.B.); (E.H.A.); (S.G.A.)
- Institute of Physical Problems, Baku State University, Ministry of Science and Education, Baku Az1148, Azerbaijan;
| | - Zakir A. Jahangirli
- Institute of Physics, Ministry of Science and Education, Baku Az1143, Azerbaijan; (A.H.B.); (E.H.A.); (S.G.A.)
- Institute of Physical Problems, Baku State University, Ministry of Science and Education, Baku Az1148, Azerbaijan;
| | - Saida G. Asadullayeva
- Institute of Physics, Ministry of Science and Education, Baku Az1143, Azerbaijan; (A.H.B.); (E.H.A.); (S.G.A.)
| | - Yegana N. Aliyeva
- Institute of Physical Problems, Baku State University, Ministry of Science and Education, Baku Az1148, Azerbaijan;
| | - Massimo Cuscunà
- National Research Council, Institute of Nanotechnology (NANOTEC), University c/o Campus Ecotekne, Via per Monteroni, 73100 Lecce, Italy; (D.L.); (M.E.); (G.B.); (D.S.); (D.M.T.)
| | - Daniela Lorenzo
- National Research Council, Institute of Nanotechnology (NANOTEC), University c/o Campus Ecotekne, Via per Monteroni, 73100 Lecce, Italy; (D.L.); (M.E.); (G.B.); (D.S.); (D.M.T.)
| | - Marco Esposito
- National Research Council, Institute of Nanotechnology (NANOTEC), University c/o Campus Ecotekne, Via per Monteroni, 73100 Lecce, Italy; (D.L.); (M.E.); (G.B.); (D.S.); (D.M.T.)
| | - Gianluca Balestra
- National Research Council, Institute of Nanotechnology (NANOTEC), University c/o Campus Ecotekne, Via per Monteroni, 73100 Lecce, Italy; (D.L.); (M.E.); (G.B.); (D.S.); (D.M.T.)
- Department of Mathematics and Physics ‘‘Ennio De Giorgi”, University of Salento, c/o Campus Ecotekne, Via per Monteroni, 73100 Lecce, Italy
| | - Daniela Simeone
- National Research Council, Institute of Nanotechnology (NANOTEC), University c/o Campus Ecotekne, Via per Monteroni, 73100 Lecce, Italy; (D.L.); (M.E.); (G.B.); (D.S.); (D.M.T.)
| | - David Maria Tobaldi
- National Research Council, Institute of Nanotechnology (NANOTEC), University c/o Campus Ecotekne, Via per Monteroni, 73100 Lecce, Italy; (D.L.); (M.E.); (G.B.); (D.S.); (D.M.T.)
| | - Daniel Abou-Ras
- Helmholtz-Zentrum Berlin for Materials and Energy (HZB), Department of Structure and Dynamics of Energy Materials, 14109 Berlin, Germany; (D.A.-R.); (S.S.)
| | - Susan Schorr
- Helmholtz-Zentrum Berlin for Materials and Energy (HZB), Department of Structure and Dynamics of Energy Materials, 14109 Berlin, Germany; (D.A.-R.); (S.S.)
- Institute of Geological Sciences, Free University of Berlin, 14195 Berlin, Germany
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5
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Mahmoudi A, Bouaziz M, Chapuis N, Kremer G, Chaste J, Romanin D, Pala M, Bertran F, Fèvre PL, Gerber IC, Patriarche G, Oehler F, Wallart X, Ouerghi A. Quasi van der Waals Epitaxy of Rhombohedral-Stacked Bilayer WSe 2 on GaP(111) Heterostructure. ACS Nano 2023; 17:21307-21316. [PMID: 37856436 DOI: 10.1021/acsnano.3c05818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2023]
Abstract
The growth of bilayers of two-dimensional (2D) materials on conventional 3D semiconductors results in 2D/3D hybrid heterostructures, which can provide additional advantages over more established 3D semiconductors while retaining some specificities of 2D materials. Understanding and exploiting these phenomena hinge on knowing the electronic properties and the hybridization of these structures. Here, we demonstrate that a rhombohedral-stacked bilayer (AB stacking) can be obtained by molecular beam epitaxy growth of tungsten diselenide (WSe2) on a gallium phosphide (GaP) substrate. We confirm the presence of 3R-stacking of the WSe2 bilayer structure using scanning transmission electron microscopy (STEM) and micro-Raman spectroscopy. Also, we report high-resolution angle-resolved photoemission spectroscopy (ARPES) on our rhombohedral-stacked WSe2 bilayer grown on a GaP(111)B substrate. Our ARPES measurements confirm the expected valence band structure of WSe2 with the band maximum located at the Γ point of the Brillouin zone. The epitaxial growth of WSe2/GaP(111)B helps to understand the fundamental properties of these 2D/3D heterostructures, toward their implementation in future devices.
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Affiliation(s)
- Aymen Mahmoudi
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120 Palaiseau, France
| | - Meryem Bouaziz
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120 Palaiseau, France
| | - Niels Chapuis
- Univ. Lille, CNRS, Centrale Lille, JUNIA ISEN, Univ. Polytechnique Hauts de France, UMR 8520-IEMN F59000 Lille, France
| | - Geoffroy Kremer
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120 Palaiseau, France
| | - Julien Chaste
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120 Palaiseau, France
| | - Davide Romanin
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120 Palaiseau, France
| | - Marco Pala
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120 Palaiseau, France
| | - François Bertran
- Synchrotron SOLEIL, L'Orme des Merisiers, Départementale 128, 91190 Saint-Aubin, France
| | - Patrick Le Fèvre
- Synchrotron SOLEIL, L'Orme des Merisiers, Départementale 128, 91190 Saint-Aubin, France
| | - Iann C Gerber
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue de Rangueil, 31077 Toulouse, France
| | - Gilles Patriarche
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120 Palaiseau, France
| | - Fabrice Oehler
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120 Palaiseau, France
| | - Xavier Wallart
- Univ. Lille, CNRS, Centrale Lille, JUNIA ISEN, Univ. Polytechnique Hauts de France, UMR 8520-IEMN F59000 Lille, France
| | - Abdelkarim Ouerghi
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120 Palaiseau, France
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6
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Baek JH, Kim HG, Lim SY, Hong SC, Chang Y, Ryu H, Jung Y, Jang H, Kim J, Zhang Y, Watanabe K, Taniguchi T, Huang PY, Cheong H, Kim M, Lee GH. Thermally induced atomic reconstruction into fully commensurate structures of transition metal dichalcogenide layers. Nat Mater 2023:10.1038/s41563-023-01690-2. [PMID: 37828101 DOI: 10.1038/s41563-023-01690-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 09/13/2023] [Indexed: 10/14/2023]
Abstract
Twist angle between two-dimensional layers is a critical parameter that determines their interfacial properties, such as moiré excitons and interfacial ferro-electricity. To achieve better control over these properties for fundamental studies and various applications, considerable efforts have been made to manipulate twist angle. However, due to mechanical limitations and the inevitable formation of incommensurate regions, there remains a challenge in attaining perfect alignment of crystalline orientation. Here we report a thermally induced atomic reconstruction of randomly stacked transition metal dichalcogenide multilayers into fully commensurate heterostructures with zero twist angle by encapsulation annealing, regardless of twist angles of as-stacked samples and lattice mismatches. We also demonstrate the selective formation of R- and H-type fully commensurate phases with a seamless lateral junction using chemical vapour-deposited transition metal dichalcogenides. The resulting fully commensurate phases exhibit strong photoluminescence enhancement of the interlayer excitons, even at room temperature, due to their commensurate structure with aligned momentum coordinates. Our work not only demonstrates a way to fabricate zero-twisted, two-dimensional bilayers with R- and H-type configurations, but also provides a platform for studying their unexplored properties.
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Affiliation(s)
- Ji-Hwan Baek
- Department of Material Science and Engineering, Seoul National University, Seoul, Korea
| | - Hyoung Gyun Kim
- Department of Material Science and Engineering, Seoul National University, Seoul, Korea
| | - Soo Yeon Lim
- Department of Physics, Sogang University, Seoul, Korea
| | - Seong Chul Hong
- Department of Material Science and Engineering, Seoul National University, Seoul, Korea
| | - Yunyeong Chang
- Department of Material Science and Engineering, Seoul National University, Seoul, Korea
| | - Huije Ryu
- Department of Material Science and Engineering, Seoul National University, Seoul, Korea
| | - Yeonjoon Jung
- Department of Material Science and Engineering, Seoul National University, Seoul, Korea
| | - Hajung Jang
- Department of Physics, Sogang University, Seoul, Korea
| | - Jungcheol Kim
- Department of Physics, Sogang University, Seoul, Korea
| | - Yichao Zhang
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana-Champaign, IL, USA
| | - Kenji Watanabe
- Research Center for Electronic and Optical Materials, National Institute for Materials Science, Tsukuba, Japan
| | - Takashi Taniguchi
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Pinshane Y Huang
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana-Champaign, IL, USA
| | | | - Miyoung Kim
- Department of Material Science and Engineering, Seoul National University, Seoul, Korea
| | - Gwan-Hyoung Lee
- Department of Material Science and Engineering, Seoul National University, Seoul, Korea.
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7
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Pimenta Martins LG, Ruiz-Tijerina DA, Occhialini CA, Park JH, Song Q, Lu AY, Venezuela P, Cançado LG, Mazzoni MSC, Matos MJS, Kong J, Comin R. Pressure tuning of minibands in MoS 2/WSe 2 heterostructures revealed by moiré phonons. Nat Nanotechnol 2023; 18:1147-1153. [PMID: 37322144 DOI: 10.1038/s41565-023-01413-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 05/08/2023] [Indexed: 06/17/2023]
Abstract
Moiré superlattices of two-dimensional heterostructures arose as a new platform to investigate emergent behaviour in quantum solids with unprecedented tunability. To glean insights into the physics of these systems, it is paramount to discover new probes of the moiré potential and moiré minibands, as well as their dependence on external tuning parameters. Hydrostatic pressure is a powerful control parameter, since it allows to continuously and reversibly enhance the moiré potential. Here we use high pressure to tune the minibands in a rotationally aligned MoS2/WSe2 moiré heterostructure, and show that their evolution can be probed via moiré phonons. The latter are Raman-inactive phonons from the individual layers that are activated by the moiré potential. Moiré phonons manifest themselves as satellite Raman peaks arising exclusively from the heterostructure region, increasing in intensity and frequency under applied pressure. Further theoretical analysis reveals that their scattering rate is directly connected to the moiré potential strength. By comparing the experimental and calculated pressure-induced enhancement, we obtain numerical estimates for the moiré potential amplitude and its pressure dependence. The present work establishes moiré phonons as a sensitive probe of the moiré potential as well as the electronic structures of moiré systems.
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Affiliation(s)
| | - David A Ruiz-Tijerina
- Departamento de Física Química, Instituto de Física, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | - Connor A Occhialini
- Physics Department, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Ji-Hoon Park
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Qian Song
- Physics Department, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Ang-Yu Lu
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Pedro Venezuela
- Instituto de Física, Universidade Federal Fluminense, Niterói, Brazil
| | - Luiz G Cançado
- Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Mário S C Mazzoni
- Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Matheus J S Matos
- Departamento de Física, Universidade Federal de Ouro Preto, Ouro Preto, Brazil
| | - Jing Kong
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Riccardo Comin
- Physics Department, Massachusetts Institute of Technology, Cambridge, MA, USA.
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8
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Lamsaadi H, Beret D, Paradisanos I, Renucci P, Lagarde D, Marie X, Urbaszek B, Gan Z, George A, Watanabe K, Taniguchi T, Turchanin A, Lombez L, Combe N, Paillard V, Poumirol JM. Kapitza-resistance-like exciton dynamics in atomically flat MoSe 2-WSe 2 lateral heterojunction. Nat Commun 2023; 14:5881. [PMID: 37735478 PMCID: PMC10514293 DOI: 10.1038/s41467-023-41538-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 09/08/2023] [Indexed: 09/23/2023] Open
Abstract
Being able to control the neutral excitonic flux is a mandatory step for the development of future room-temperature two-dimensional excitonic devices. Semiconducting Monolayer Transition Metal Dichalcogenides (TMD-ML) with extremely robust and mobile excitons are highly attractive in this regard. However, generating an efficient and controlled exciton transport over long distances is a very challenging task. Here we demonstrate that an atomically sharp TMD-ML lateral heterostructure (MoSe2-WSe2) transforms the isotropic exciton diffusion into a unidirectional excitonic flow through the junction. Using tip-enhanced photoluminescence spectroscopy (TEPL) and a modified exciton transfer model, we show a discontinuity of the exciton density distribution on each side of the interface. We introduce the concept of exciton Kapitza resistance, by analogy with the interfacial thermal resistance referred to as Kapitza resistance. By comparing different heterostructures with or without top hexagonal boron nitride (hBN) layer, we deduce that the transport properties can be controlled, over distances far greater than the junction width, by the exciton density through near-field engineering and/or laser power density. This work provides a new approach for controlling the neutral exciton flow, which is key toward the conception of excitonic devices.
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Affiliation(s)
| | - Dorian Beret
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077, Toulouse, France
| | - Ioannis Paradisanos
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077, Toulouse, France
- Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, Heraklion, 70013, Greece
| | - Pierre Renucci
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077, Toulouse, France
| | - Delphine Lagarde
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077, Toulouse, France
| | - Xavier Marie
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077, Toulouse, France
| | - Bernhard Urbaszek
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077, Toulouse, France
- Institute of Condensed Matter Physics, Technische Universität Darmstadt, Darmstadt, Germany
| | - Ziyang Gan
- Friedrich Schiller University Jena, Institute of Physical Chemistry, 07743, Jena, Germany
| | - Antony George
- Friedrich Schiller University Jena, Institute of Physical Chemistry, 07743, Jena, Germany
- Abbe Centre of Photonics, 07745, Jena, Germany
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Andrey Turchanin
- Friedrich Schiller University Jena, Institute of Physical Chemistry, 07743, Jena, Germany
- Abbe Centre of Photonics, 07745, Jena, Germany
| | - Laurent Lombez
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077, Toulouse, France.
| | - Nicolas Combe
- CEMES-CNRS, Université de Toulouse, Toulouse, France
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9
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Naito H, Makino Y, Zhang W, Ogawa T, Endo T, Sannomiya T, Kaneda M, Hashimoto K, Lim HE, Nakanishi Y, Watanabe K, Taniguchi T, Matsuda K, Miyata Y. High-throughput dry transfer and excitonic properties of twisted bilayers based on CVD-grown transition metal dichalcogenides. Nanoscale Adv 2023; 5:5115-5121. [PMID: 37705802 PMCID: PMC10496764 DOI: 10.1039/d3na00371j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 08/21/2023] [Indexed: 09/15/2023]
Abstract
van der Waals (vdW) layered materials have attracted much attention because their physical properties can be controlled by varying the twist angle and layer composition. However, such twisted vdW assemblies are often prepared using mechanically exfoliated monolayer flakes with unintended shapes through a time-consuming search for such materials. Here, we report the rapid and dry fabrication of twisted multilayers using chemical vapor deposition (CVD) grown transition metal chalcogenide (TMDC) monolayers. By improving the adhesion of an acrylic resin stamp to the monolayers, the single crystals of various TMDC monolayers with desired grain size and density on a SiO2/Si substrate can be efficiently picked up. The present dry transfer process demonstrates the one-step fabrication of more than 100 twisted bilayers and the sequential stacking of a twisted 10-layer MoS2 single crystal. Furthermore, we also fabricated hBN-encapsulated TMDC monolayers and various twisted bilayers including MoSe2/MoS2, MoSe2/WSe2, and MoSe2/WS2. The interlayer interaction and quality of dry-transferred, CVD-grown TMDCs were characterized by using photoluminescence (PL), cathodoluminescence (CL) spectroscopy, and cross-sectional electron microscopy. The prominent PL peaks of interlayer excitons can be observed for MoSe2/MoS2 and MoSe2/WSe2 with small twist angles at room temperature. We also found that the optical spectra were locally modulated due to nanosized bubbles, which are formed by the presence of interface carbon impurities. The present findings indicate the widely applicable potential of the present method and enable an efficient search of the emergent optical and electrical properties of TMDC-based vdW heterostructures.
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Affiliation(s)
- Hibiki Naito
- Department of Physics, Tokyo Metropolitan University Hachioji 192-0397 Japan
| | - Yasuyuki Makino
- Department of Physics, Tokyo Metropolitan University Hachioji 192-0397 Japan
| | - Wenjin Zhang
- Department of Physics, Tokyo Metropolitan University Hachioji 192-0397 Japan
| | - Tomoya Ogawa
- Department of Physics, Tokyo Metropolitan University Hachioji 192-0397 Japan
| | - Takahiko Endo
- Department of Physics, Tokyo Metropolitan University Hachioji 192-0397 Japan
| | - Takumi Sannomiya
- Department of Materials Science and Engineering, Tokyo Institute of Technology Yokohama 226-8503 Japan
| | - Masahiko Kaneda
- Department of Physics, Tokyo Metropolitan University Hachioji 192-0397 Japan
| | - Kazuki Hashimoto
- Department of Physics, Tokyo Metropolitan University Hachioji 192-0397 Japan
| | - Hong En Lim
- Department of Chemistry, Saitama University Saitama 338-8570 Japan
| | - Yusuke Nakanishi
- Department of Physics, Tokyo Metropolitan University Hachioji 192-0397 Japan
| | - Kenji Watanabe
- Research Center for Electronic and Optical Materials, NIMS Tsukuba 305-0044 Japan
| | - Takashi Taniguchi
- Research Center for Materials Nanoarchitectonics, NIMS Tsukuba 305-0044 Japan
| | - Kazunari Matsuda
- Institute of Advanced Energy, Kyoto University Kyoto 611-0011 Japan
| | - Yasumitsu Miyata
- Department of Physics, Tokyo Metropolitan University Hachioji 192-0397 Japan
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10
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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 Lett 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] [What about the content of this article? (0)] [Affiliation(s)] [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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11
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Louca C, Genco A, Chiavazzo S, Lyons TP, Randerson S, Trovatello C, Claronino P, Jayaprakash R, Hu X, Howarth J, Watanabe K, Taniguchi T, Dal Conte S, Gorbachev R, Lidzey DG, Cerullo G, Kyriienko O, Tartakovskii AI. Interspecies exciton interactions lead to enhanced nonlinearity of dipolar excitons and polaritons in MoS 2 homobilayers. Nat Commun 2023; 14:3818. [PMID: 37369664 DOI: 10.1038/s41467-023-39358-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 06/09/2023] [Indexed: 06/29/2023] Open
Abstract
Nonlinear interactions between excitons strongly coupled to light are key for accessing quantum many-body phenomena in polariton systems. Atomically-thin two-dimensional semiconductors provide an attractive platform for strong light-matter coupling owing to many controllable excitonic degrees of freedom. Among these, the recently emerged exciton hybridization opens access to unexplored excitonic species, with a promise of enhanced interactions. Here, we employ hybridized interlayer excitons (hIX) in bilayer MoS2 to achieve highly nonlinear excitonic and polaritonic effects. Such interlayer excitons possess an out-of-plane electric dipole as well as an unusually large oscillator strength allowing observation of dipolar polaritons (dipolaritons) in bilayers in optical microcavities. Compared to excitons and polaritons in MoS2 monolayers, both hIX and dipolaritons exhibit ≈ 8 times higher nonlinearity, which is further strongly enhanced when hIX and intralayer excitons, sharing the same valence band, are excited simultaneously. This provides access to an unusual nonlinear regime which we describe theoretically as a mixed effect of Pauli exclusion and exciton-exciton interactions enabled through charge tunnelling. The presented insight into many-body interactions provides new tools for accessing few-polariton quantum correlations.
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Affiliation(s)
- Charalambos Louca
- Department of Physics and Astronomy, The University of Sheffield, Sheffield, S3 7RH, UK.
| | - Armando Genco
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci, 32, Milano, 20133, Italy.
| | - Salvatore Chiavazzo
- Department of Physics, University of Exeter, Stocker Road, Exeter, EX4 4PY, UK
| | - Thomas P Lyons
- Department of Physics and Astronomy, The University of Sheffield, Sheffield, S3 7RH, UK
- RIKEN Center for Emergent Matter Science, Wako, Saitama, 351-0198, Japan
| | - Sam Randerson
- Department of Physics and Astronomy, The University of Sheffield, Sheffield, S3 7RH, UK
| | - Chiara Trovatello
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci, 32, Milano, 20133, Italy
- Department of Mechanical Engineering, Columbia University, NY, 10027, New York, USA
| | - Peter Claronino
- Department of Physics and Astronomy, The University of Sheffield, Sheffield, S3 7RH, UK
- Department of Physics and Mathematics, University of Hull, Rober Blackburn, Hull HU6 7RX, UK
| | - Rahul Jayaprakash
- Department of Physics and Astronomy, The University of Sheffield, Sheffield, S3 7RH, UK
| | - Xuerong Hu
- Department of Physics and Astronomy, The University of Sheffield, Sheffield, S3 7RH, UK
| | - James Howarth
- National Graphene Institute, University of Manchester, Manchester, UK
- Department of Physics and Astronomy, University of Manchester, Manchester, UK
| | - 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
| | - Stefano Dal Conte
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci, 32, Milano, 20133, Italy
| | - Roman Gorbachev
- National Graphene Institute, University of Manchester, Manchester, UK
- Department of Physics and Astronomy, University of Manchester, Manchester, UK
| | - David G Lidzey
- Department of Physics and Astronomy, The University of Sheffield, Sheffield, S3 7RH, UK
| | - Giulio Cerullo
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci, 32, Milano, 20133, Italy
| | - Oleksandr Kyriienko
- Department of Physics, University of Exeter, Stocker Road, Exeter, EX4 4PY, UK
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12
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Zhou J, Cui J, Du S, Zhao Z, Guo J, Li S, Zhang W, Liu N, Li X, Bai Q, Guo Y, Mi S, Cheng Z, He L, Nie JC, Yang Y, Dou R. A natural indirect-to-direct band gap transition in artificially fabricated MoS 2 and MoSe 2 flowers. Nanoscale 2023; 15:7792-7802. [PMID: 37021968 DOI: 10.1039/d3nr00477e] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Twisted bilayer (tB) transition metal dichalcogenide (TMD) structures formed from two pieces of a periodic pattern overlaid with a relative twist manifest novel electronic and optical properties and correlated electronic phenomena. Here, twisted flower-like MoS2 and MoSe2 bilayers were artificially fabricated by the chemical vapor deposition (CVD) method. Photoluminescence (PL) studies demonstrated that an energy band structural transition from the indirect gap to the direct gap happened in the region away from the flower center in tB MoS2 (MoSe2) flower patterns, accompanied by an enhanced PL intensity. The indirect-to-direct-gap transition in the tB-MoS2 (MoSe2) flower dominantly originated from a gradually enlarged interlayer spacing and thus, interlayer decoupling during the spiral growth of tB flower patterns. Meanwhile, the expanded interlayer spacing resulted in a decreased effective mass of the electrons. This means that the charged exciton (trion) population was reduced and the neutral exciton density was increased to obtain the upgraded PL intensity in the off-center region. Our experimental results were further evidenced by the density functional theory (DFT) calculations of the energy band structures and the effective masses of electrons and holes for the artificial tB-MoS2 flower with different interlayer spacings. The single-layer behavior of tB flower-like homobilayers provided a viable route to finely manipulate the energy band gap and the corresponding exotic optical properties by locally tuning the stacked structures and to satisfy the real requirement in TMD-based optoelectronic devices.
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Affiliation(s)
- Jun Zhou
- Department of Physics, Beijing Normal, University, Beijing, 100875, China.
| | - Juan Cui
- LCP, Inst Appl Phys & Computation Math, Beijing 100088, China.
| | - Shuo Du
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Zihan Zhao
- Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, 100875, China
| | - Jianfeng Guo
- Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872, P. R. China
| | - Songyang Li
- Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872, P. R. China
| | - Weifeng Zhang
- Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, 100875, China
| | - Nan Liu
- Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, 100875, China
| | - Xiaotian Li
- Department of Physics, Beijing Normal, University, Beijing, 100875, China.
| | - Qinghu Bai
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Yang Guo
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Shuo Mi
- Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872, P. R. China
| | - Zhihai Cheng
- Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872, P. R. China
| | - Lin He
- Department of Physics, Beijing Normal, University, Beijing, 100875, China.
| | - J C Nie
- Department of Physics, Beijing Normal, University, Beijing, 100875, China.
| | - Yu Yang
- LCP, Inst Appl Phys & Computation Math, Beijing 100088, China.
| | - Ruifen Dou
- Department of Physics, Beijing Normal, University, Beijing, 100875, China.
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13
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Rosati R, Paradisanos I, Huang L, Gan Z, George A, Watanabe K, Taniguchi T, Lombez L, Renucci P, Turchanin A, Urbaszek B, Malic E. Interface engineering of charge-transfer excitons in 2D lateral heterostructures. Nat Commun 2023; 14:2438. [PMID: 37117167 PMCID: PMC10147613 DOI: 10.1038/s41467-023-37889-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 04/04/2023] [Indexed: 04/30/2023] Open
Abstract
The existence of bound charge transfer (CT) excitons at the interface of monolayer lateral heterojunctions has been debated in literature, but contrary to the case of interlayer excitons in vertical heterostructure their observation still has to be confirmed. Here, we present a microscopic study investigating signatures of bound CT excitons in photoluminescence spectra at the interface of hBN-encapsulated lateral MoSe2-WSe2 heterostructures. Based on a fully microscopic and material-specific theory, we reveal the many-particle processes behind the formation of CT excitons and how they can be tuned via interface- and dielectric engineering. For junction widths smaller than the Coulomb-induced Bohr radius we predict the appearance of a low-energy CT exciton. The theoretical prediction is compared with experimental low-temperature photoluminescence measurements showing emission in the bound CT excitons energy range. We show that for hBN-encapsulated heterostructures, CT excitons exhibit small binding energies of just a few tens meV and at the same time large dipole moments, making them promising materials for optoelectronic applications (benefiting from an efficient exciton dissociation and fast dipole-driven exciton propagation). Our joint theory-experiment study presents a significant step towards a microscopic understanding of optical properties of technologically promising 2D lateral heterostructures.
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Affiliation(s)
- Roberto Rosati
- Department of Physics, Philipps-Universität Marburg, Renthof 7, D-35032, Marburg, Germany.
| | - Ioannis Paradisanos
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077, Toulouse, France
| | - Libai Huang
- Department of Chemistry, Purdue University, West Lafayette, IN, USA
| | - Ziyang Gan
- Friedrich Schiller University Jena, Institute of Physical Chemistry, 07743, Jena, Germany
- Abbe Centre of Photonics, 07745, Jena, Germany
| | - Antony George
- Friedrich Schiller University Jena, Institute of Physical Chemistry, 07743, Jena, Germany
- Abbe Centre of Photonics, 07745, Jena, Germany
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Laurent Lombez
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077, Toulouse, France
| | - Pierre Renucci
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077, Toulouse, France
| | - Andrey Turchanin
- Friedrich Schiller University Jena, Institute of Physical Chemistry, 07743, Jena, Germany
- Abbe Centre of Photonics, 07745, Jena, Germany
| | - Bernhard Urbaszek
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077, Toulouse, France
- Institute of Condensed Matter Physics, Technische Universität Darmstadt, 64289, Darmstadt, Germany
| | - Ermin Malic
- Department of Physics, Philipps-Universität Marburg, Renthof 7, D-35032, Marburg, Germany
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14
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Ferrera M, Sharma A, Milekhin I, Pan Y, Convertino D, Pace S, Orlandini G, Peci E, Ramò L, Magnozzi M, Coletti C, Salvan G, Zahn DRT, Canepa M, Bisio F. Local dielectric function of hBN-encapsulated WS 2flakes grown by chemical vapor deposition. J Phys Condens Matter 2023; 35:274001. [PMID: 36996840 DOI: 10.1088/1361-648x/acc918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 03/30/2023] [Indexed: 06/19/2023]
Abstract
Hexagonal boron nitride (hBN), sometimes referred to as white graphene, receives growing interest in the scientific community, especially when combined into van der Waals (vdW) homo- and heterostacks, in which novel and interesting phenomena may arise. hBN is also commonly used in combination with two-dimensional (2D) semiconducting transition metal dichalcogenides (TMDCs). The realization of hBN-encapsulated TMDC homo- and heterostacks can indeed offer opportunities to investigate and compare TMDC excitonic properties in various stacking configurations. In this work, we investigate the optical response at the micrometric scale of mono- and homo-bilayer WS2grown by chemical vapor deposition and encapsulated between two single layers of hBN. Imaging spectroscopic ellipsometry is exploited to extract the local dielectric functions across one single WS2flake and detect the evolution of excitonic spectral features from monolayer to bilayer regions. Exciton energies undergo a redshift by passing from hBN-encapsulated single layer to homo-bilayer WS2, as also confirmed by photoluminescence spectra. Our results can provide a reference for the study of the dielectric properties of more complex systems where hBN is combined with other 2D vdW materials into heterostructures and are stimulating towards the investigation of the optical response of other technologically-relevant heterostacks.
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Affiliation(s)
- Marzia Ferrera
- OptMatLab, Physics Department, Università di Genova, via Dodecaneso 33, 16146 Genova, Italy
- Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova, Italy
| | - Apoorva Sharma
- Semiconductor Physics, Chemnitz University of Technology, D-09107 Chemnitz, Germany
| | - Ilya Milekhin
- Semiconductor Physics, Chemnitz University of Technology, D-09107 Chemnitz, Germany
- Center for Materials, Architectures and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, D-09107 Chemnitz, Germany
| | - Yang Pan
- Semiconductor Physics, Chemnitz University of Technology, D-09107 Chemnitz, Germany
- Center for Materials, Architectures and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, D-09107 Chemnitz, Germany
| | - Domenica Convertino
- Center for Nanotechnology Innovation IIT@NEST, Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Simona Pace
- Center for Nanotechnology Innovation IIT@NEST, Piazza San Silvestro 12, 56127 Pisa, Italy
- Graphene Labs, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova, Italy
| | - Giorgio Orlandini
- Center for Nanotechnology Innovation IIT@NEST, Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Ermes Peci
- OptMatLab, Physics Department, Università di Genova, via Dodecaneso 33, 16146 Genova, Italy
| | - Lorenzo Ramò
- OptMatLab, Physics Department, Università di Genova, via Dodecaneso 33, 16146 Genova, Italy
| | - Michele Magnozzi
- OptMatLab, Physics Department, Università di Genova, via Dodecaneso 33, 16146 Genova, Italy
- INFN, Sezione di Genova, via Dodecaneso 33, 16146 Genova, Italy
| | - Camilla Coletti
- Center for Nanotechnology Innovation IIT@NEST, Piazza San Silvestro 12, 56127 Pisa, Italy
- Graphene Labs, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova, Italy
| | - Georgeta Salvan
- Semiconductor Physics, Chemnitz University of Technology, D-09107 Chemnitz, Germany
| | - Dietrich R T Zahn
- Semiconductor Physics, Chemnitz University of Technology, D-09107 Chemnitz, Germany
- Center for Materials, Architectures and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, D-09107 Chemnitz, Germany
| | - Maurizio Canepa
- OptMatLab, Physics Department, Università di Genova, via Dodecaneso 33, 16146 Genova, Italy
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15
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Su J, Li X, Xu M, Zhang J, Liu X, Zheng X, Shi Y, Zhang Q. Enhancing Photodetection Ability of MoS 2 Nanoscrolls via Interface Engineering. ACS Appl Mater Interfaces 2023; 15:3307-3316. [PMID: 36596237 DOI: 10.1021/acsami.2c18537] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Van der Waals semiconductors have been really confirmed in two-dimensional (2D) layered systems beyond the traditional limits of lattice-matching requirements. The extension of this concept to the 1D atomic level may generate intriguing physical functionalities due to its non-covalent bonding surface. However, whether the curvature of the lattice in such rolled-up structures affects their optoelectronic features or the performance of devices established on them remains an open question. Here, MoS2-based nanoscrolls were obtained by virtue of an alkaline solution-assisted method and the 0D/1D (BaTiO3/MoS2) strategy to tune their optoelectronic properties and improve the light sensing performance was explored. The capillary force generated by a drop of NaHCO3 solution could drive the delamination of nanosheets from the underlying substrate and a spontaneous rolling-up process. The package of BaTiO3 particles in MoS2 nanoscrolls has been evident by TEM image, and the optical characterizations were mirrored via micro-Raman spectroscopy and photoluminescence. These bare MoS2 nanoscrolls reveal a reduced photoresponse compared to the plane structures due to the curvature of the lattice. However, such BaTiO3/MoS2 nanoscrolls exhibit a significantly improved photodetection (Rhybrid = 73.9 A/W vs Ronly = 1.1 A/W and R2D = 1.5 A/W at 470 nm, 0.58 mW·cm-2), potentially due to the carrier extraction/injection occurring between BaTiO3 and MoS2. This study thereby provides an insight into 1D van der Waals material community and demonstrates a general approach to fabricate high-performance 1D van der Waals optoelectronic devices.
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Affiliation(s)
- Jun Su
- Center for Advanced Optoelectronic Materials, College of Materials and Environmental Engineering, Hangzhou Dianzi University (HDU), Hangzhou 310018, China
- Key Laboratory of Novel Materials for Sensor of Zhejiang Province, Hangzhou Dianzi University (HDU), Hangzhou 310018, P. R. China
| | - Xin Li
- Center for Advanced Optoelectronic Materials, College of Materials and Environmental Engineering, Hangzhou Dianzi University (HDU), Hangzhou 310018, China
- Key Laboratory of Novel Materials for Sensor of Zhejiang Province, Hangzhou Dianzi University (HDU), Hangzhou 310018, P. R. China
| | - Minxuan Xu
- Center for Advanced Optoelectronic Materials, College of Materials and Environmental Engineering, Hangzhou Dianzi University (HDU), Hangzhou 310018, China
- Key Laboratory of Novel Materials for Sensor of Zhejiang Province, Hangzhou Dianzi University (HDU), Hangzhou 310018, P. R. China
| | - Jian Zhang
- Key Laboratory of Novel Materials for Sensor of Zhejiang Province, Hangzhou Dianzi University (HDU), Hangzhou 310018, P. R. China
| | - Xiaolian Liu
- Key Laboratory of Novel Materials for Sensor of Zhejiang Province, Hangzhou Dianzi University (HDU), Hangzhou 310018, P. R. China
| | - Xin Zheng
- Center for Advanced Optoelectronic Materials, College of Materials and Environmental Engineering, Hangzhou Dianzi University (HDU), Hangzhou 310018, China
- Key Laboratory of Novel Materials for Sensor of Zhejiang Province, Hangzhou Dianzi University (HDU), Hangzhou 310018, P. R. China
| | - Yueqin Shi
- Center for Advanced Optoelectronic Materials, College of Materials and Environmental Engineering, Hangzhou Dianzi University (HDU), Hangzhou 310018, China
- Key Laboratory of Novel Materials for Sensor of Zhejiang Province, Hangzhou Dianzi University (HDU), Hangzhou 310018, P. R. China
| | - Qi Zhang
- Center for Advanced Optoelectronic Materials, College of Materials and Environmental Engineering, Hangzhou Dianzi University (HDU), Hangzhou 310018, China
- Key Laboratory of Novel Materials for Sensor of Zhejiang Province, Hangzhou Dianzi University (HDU), Hangzhou 310018, P. R. China
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16
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Gan Z, Paradisanos I, Estrada-Real A, Picker J, Najafidehaghani E, Davies F, Neumann C, Robert C, Wiecha P, Watanabe K, Taniguchi T, Marie X, Biskupek J, Mundszinger M, Leiter R, Kaiser U, Krasheninnikov AV, Urbaszek B, George A, Turchanin A. Chemical Vapor Deposition of High-Optical-Quality Large-Area Monolayer Janus Transition Metal Dichalcogenides. Adv Mater 2022; 34:e2205226. [PMID: 35906951 DOI: 10.1002/adma.202205226] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Indexed: 06/15/2023]
Abstract
One-pot chemical vapor deposition (CVD) growth of large-area Janus SeMoS monolayers is reported, with the asymmetric top (Se) and bottom (S) chalcogen atomic planes with respect to the central transition metal (Mo) atoms. The formation of these 2D semiconductor monolayers takes place upon the thermodynamic-equilibrium-driven exchange of the bottom Se atoms of the initially grown MoSe2 single crystals on gold foils with S atoms. The growth process is characterized by complementary experimental techniques including Raman and X-ray photoelectron spectroscopy, transmission electron microscopy, and the growth mechanisms are rationalized by first principle calculations. The remarkably high optical quality of the synthesized Janus monolayers is demonstrated by optical and magneto-optical measurements which reveal the strong exciton-phonon coupling and enable an exciton g-factor of -3.3.
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Affiliation(s)
- Ziyang Gan
- Institute of Physical Chemistry, Friedrich Schiller University Jena, 07743, Jena, Germany
| | | | - Ana Estrada-Real
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, Toulouse, 31077, France
| | - Julian Picker
- Institute of Physical Chemistry, Friedrich Schiller University Jena, 07743, Jena, Germany
| | - Emad Najafidehaghani
- Institute of Physical Chemistry, Friedrich Schiller University Jena, 07743, Jena, Germany
| | - Francis Davies
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Centre Dresden-Rossendorf, 01328, Dresden, Germany
| | - Christof Neumann
- Institute of Physical Chemistry, Friedrich Schiller University Jena, 07743, Jena, Germany
| | - Cedric Robert
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, Toulouse, 31077, France
| | - Peter Wiecha
- LAAS-CNRS, Université de Toulouse, Toulouse, 31400, France
| | - 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
| | - Xavier Marie
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, Toulouse, 31077, France
| | - Johannes Biskupek
- Central Facility of Electron Microscopy, Electron Microscopy Group of Material Science, University of Ulm, D-89081, Ulm, Germany
| | - Manuel Mundszinger
- Central Facility of Electron Microscopy, Electron Microscopy Group of Material Science, University of Ulm, D-89081, Ulm, Germany
| | - Robert Leiter
- Central Facility of Electron Microscopy, Electron Microscopy Group of Material Science, University of Ulm, D-89081, Ulm, Germany
| | - Ute Kaiser
- Central Facility of Electron Microscopy, Electron Microscopy Group of Material Science, University of Ulm, D-89081, Ulm, Germany
| | - Arkady V Krasheninnikov
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Centre Dresden-Rossendorf, 01328, Dresden, Germany
- Department of Applied Physics, Aalto University, Aalto, 00076, Finland
| | - Bernhard Urbaszek
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, Toulouse, 31077, France
- Department of Physics, Technische Universität Darmstadt, 64289, Darmstadt, Germany
| | - Antony George
- Institute of Physical Chemistry, Friedrich Schiller University Jena, 07743, Jena, Germany
- Abbe Center of Photonics, 07745, Jena, Germany
| | - Andrey Turchanin
- Institute of Physical Chemistry, Friedrich Schiller University Jena, 07743, Jena, Germany
- Abbe Center of Photonics, 07745, Jena, Germany
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17
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Bhatnagar M, Woźniak T, Kipczak Ł, Zawadzka N, Olkowska-pucko K, Grzeszczyk M, Pawłowski J, Watanabe K, Taniguchi T, Babiński A, Molas MR. Temperature induced modulation of resonant Raman scattering in bilayer 2H-MoS2. Sci Rep 2022; 12. [PMID: 35986062 PMCID: PMC9391345 DOI: 10.1038/s41598-022-18439-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 08/11/2022] [Indexed: 11/15/2022] Open
Abstract
The temperature evolution of the resonant Raman scattering from high-quality bilayer 2H-MoS\documentclass[12pt]{minimal}
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\begin{document}$$_{2}$$\end{document}2 encapsulated in hexagonal BN flakes is presented. The observed resonant Raman scattering spectrum as initiated by the laser energy of 1.96 eV, close to the A excitonic resonance, shows rich and distinct vibrational features that are otherwise not observed in non-resonant scattering. The appearance of 1st and 2nd order phonon modes is unambiguously observed in a broad range of temperatures from 5 to 320 K. The spectrum includes the Raman-active modes, i.e. E\documentclass[12pt]{minimal}
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\begin{document}$$\Gamma$$\end{document}Γ). The temperature evolution of the Raman scattering spectrum brings forward key observations, as the integrated intensity profiles of different phonon modes show diverse trends. The Raman-active A\documentclass[12pt]{minimal}
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\begin{document}$$\Gamma$$\end{document}Γ) mode, which dominates the Raman scattering spectrum at T = 5 K quenches with increasing temperature. Surprisingly, at room temperature the B\documentclass[12pt]{minimal}
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18
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Liu Y, Elbanna A, Gao W, Pan J, Shen Z, Teng J. Interlayer Excitons in Transition Metal Dichalcogenide Semiconductors for 2D Optoelectronics. Adv Mater 2022; 34:e2107138. [PMID: 34700359 DOI: 10.1002/adma.202107138] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 10/13/2021] [Indexed: 06/13/2023]
Abstract
Optoelectronic materials that allow on-chip integrated light signal emitting, routing, modulation, and detection are crucial for the development of high-speed and high-throughput optical communication and computing technologies. Interlayer excitons in 2D van der Waals heterostructures, where electrons and holes are bounded by Coulomb interaction but spatially localized in different 2D layers, have recently attracted intense attention for their enticing properties and huge potential in device applications. Here, a general view of these 2D-confined hydrogen-like bosonic particles and the state-of-the-art developments with respect to the frontier concepts and prototypes is presented. Staggered type-II band alignment enables expansion of the interlayer direct bandgap from the intrinsic visible in monolayers up to the near- or even mid-infrared spectrum. Owing to large exciton binding energy, together with ultralong lifetime, room-temperature exciton devices and observation of quantum behaviors are demonstrated. With the rapid advances, it can be anticipated that future studies of interlayer excitons will not only allow the construction of all-exciton information processing circuits but will also continue to enrich the panoply of ideas on quantum phenomena.
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Affiliation(s)
- Yuanda Liu
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore, 138634, Singapore
| | - Ahmed Elbanna
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore, 138634, Singapore
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 637371, Singapore
| | - Weibo Gao
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 637371, Singapore
- The Photonics Institute and Center for Disruptive Photonic Technologies, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Jisheng Pan
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore, 138634, Singapore
| | - Zexiang Shen
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 637371, Singapore
- The Photonics Institute and Center for Disruptive Photonic Technologies, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Jinghua Teng
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore, 138634, Singapore
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19
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Xiong L, Tang T, Fan X, Liu H, Zhu P, Zhang X, Qiao W, Wang Q, Wang Z, Niu B, Wang G. Twist Angle-Dependent Interlayer Exciton in MoS2 Bilayers Revealed by Room-Temperature Reflectance. Crystals 2022; 12:761. [DOI: 10.3390/cryst12060761] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
In 2H stacking bilayer MoS2, the exciton with an interlayer nature has been evidenced due to the hybridization of hole states among both layers. The transition energy of this interlayer exciton is located between the A and B excitons. In this work, we investigate the evolution of optical properties in stacking MoS2 bilayers with the twisted angles ranging from 0° to 60°, especially focusing on the interlayer exciton. The clear modulations of the exciton responses are observed by the room-temperature reflectance. The interlayer exciton transition is observed in the artificial stacking bilayer MoS2 with the twisted angle around 60°. We found that the interlayer exciton is very sensitive to the twisted angle. Once the stacking angle deviates the 2H stacking by a few degrees, the interlayer transition is quenched. This is due to the bilayer symmetry and interlayer coupling of this unique system.
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20
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Pimenta Martins LG, Carvalho BR, Occhialini CA, Neme NP, Park JH, Song Q, Venezuela P, Mazzoni MSC, Matos MJS, Kong J, Comin R. Electronic Band Tuning and Multivalley Raman Scattering in Monolayer Transition Metal Dichalcogenides at High Pressures. ACS Nano 2022; 16:8064-8075. [PMID: 35466673 DOI: 10.1021/acsnano.2c01065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Transition metal dichalcogenides (TMDs) possess spin-valley locking and spin-split K/K' valleys, which have led to many fascinating physical phenomena. However, the electronic structure of TMDs also exhibits other conduction band minima with similar properties, the Q/Q' valleys. The intervalley K-Q scattering enables interesting physical phenomena, including multivalley superconductivity, but those effects are typically hindered in monolayer TMDs due to the large K-Q energy difference (ΔEKQ). To unlock elusive multivalley phenomena in monolayer TMDs, it is desirable to reduce ΔEKQ, while being able to sensitively probe the valley shifts and the multivalley scattering processes. Here, we use high pressure to tune the electronic properties of monolayer MoS2 and WSe2 and probe K-Q crossing and multivalley scattering via double-resonance Raman (DRR) scattering. In both systems, we observed a pressure-induced enhancement of the double-resonance LA and 2LA Raman bands, which can be attributed to a band gap opening and ΔEKQ decrease. First-principles calculations and photoluminescence measurements corroborate this scenario. In our analysis, we also addressed the multivalley nature of the DRR bands for WSe2. Our work establishes the DRR 2LA and LA bands as sensitive probes of strain-induced modifications to the electronic structure of TMDs. Conversely, their intensity could potentially be used to monitor the presence of compressive or tensile strain in TMDs. Furthermore, the ability to probe K-K' and K-Q scattering as a function of strain shall advance our understanding of different multivalley phenomena in TMDs such as superconductivity, valley coherence, and valley transport.
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Affiliation(s)
- Luiz G Pimenta Martins
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Bruno R Carvalho
- Departamento de Física, Universidade Federal do Rio Grande do Norte, Natal, Rio Grande do Norte 59078-970, Brazil
| | - Connor A Occhialini
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Natália P Neme
- Zernike Institute for Advanced Materials and Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Ji-Hoon Park
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Qian Song
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Pedro Venezuela
- Instituto de Física, Universidade Federal Fluminense, Niterói, Rio de Janeiro 24210-346, Brazil
| | - Mário S C Mazzoni
- Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil
| | - Matheus J S Matos
- Departamento de Física, Universidade Federal de Ouro Preto, Ouro Preto, Minas Gerais 35400-000, Brazil
| | - Jing Kong
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Riccardo Comin
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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21
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Qiao W, Sun H, Fan X, Jin M, Liu H, Tang T, Xiong L, Niu B, Li X, Wang G. Interlayer Coupling and Pressure Engineering in Bilayer MoS2. Crystals 2022; 12:693. [DOI: 10.3390/cryst12050693] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Controlling the interlayer coupling by tuning lattice parameters through pressure engineering is an important route for tailoring the optoelectronic properties of two-dimensional materials. In this work, we report a pressure-dependent study on the exciton transitions of bilayer MoS2 exfoliated on a diamond anvil surface. The applied hydrostatic pressure changes from ambient pressure up to 11.05 GPa using a diamond anvil cell device. Raman, photoluminescence, and reflectivity spectra at room temperature are analyzed to characterize the interlayer coupling of this bilayer system. With the increase of pressure, the indirect exciton emission disappears completely at about 5 GPa. Importantly, we clearly observed the interlayer exciton from the reflectivity spectra, which becomes invisible at a low pressure around 1.26 GPa. This indicates that the interlayer exciton is very sensitive to the hydrostatic pressure due to the oscillator strength transfer from the direct transition to the indirect one.
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22
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Huang D, Choi J, Shih CK, Li X. Excitons in semiconductor moiré superlattices. Nat Nanotechnol 2022; 17:227-238. [PMID: 35288673 DOI: 10.1038/s41565-021-01068-y] [Citation(s) in RCA: 58] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 12/06/2021] [Indexed: 06/14/2023]
Abstract
Semiconductor moiré superlattices represent a rapidly developing area of engineered photonic materials and a new platform to explore correlated electron states and quantum simulation. In this Review, we briefly introduce early experiments that identified new exciton resonances in transition metal dichalcogenide heterobilayers and discuss several topics including two types of transition metal dichalcogenide moiré superlattice, new optical selection rules, early evidence of moiré excitons, and how the resonant energy, dynamics and diffusion properties of moiré excitons can be controlled via the twist angle. To interpret optical spectra, it is important to measure the energy modulation within a moiré supercell. In this context, we describe a few scanning tunnelling microscopy experiments that measure the moiré potential landscape directly. Finally, we review a few recent experiments that applied excitonic optical spectroscopy to probe correlated electron phenomena in transition metal dichalcogenide moiré superlattices.
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Affiliation(s)
- Di Huang
- Physics Department and Center for Complex Quantum Systems, The University of Texas-Austin, Austin, TX, USA.
| | - Junho Choi
- Physics Department and Center for Complex Quantum Systems, The University of Texas-Austin, Austin, TX, USA
- Texas Materials Institute and Center for Dynamics and Control of Materials, The University of Texas-Austin, Austin, TX, USA
| | - Chih-Kang Shih
- Physics Department and Center for Complex Quantum Systems, The University of Texas-Austin, Austin, TX, USA
- Texas Materials Institute and Center for Dynamics and Control of Materials, The University of Texas-Austin, Austin, TX, USA
| | - Xiaoqin Li
- Physics Department and Center for Complex Quantum Systems, The University of Texas-Austin, Austin, TX, USA.
- Texas Materials Institute and Center for Dynamics and Control of Materials, The University of Texas-Austin, Austin, TX, USA.
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23
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McCreary KM, Phillips M, Chuang HJ, Wickramaratne D, Rosenberger M, Hellberg CS, Jonker BT. Stacking-dependent optical properties in bilayer WSe 2. Nanoscale 2021; 14:147-156. [PMID: 34904621 DOI: 10.1039/d1nr06119d] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The twist angle between the monolayers in van der Waals heterostructures provides a new degree of freedom in tuning material properties. We compare the optical properties of WSe2 homobilayers with 2H and 3R stacking using photoluminescence, Raman spectroscopy, and reflectance contrast measurements under ambient and cryogenic temperatures. Clear stacking-dependent differences are evident for all temperatures, with both photoluminescence and reflectance contrast spectra exhibiting a blue shift in spectral features in 2H compared to 3R bilayers. Density functional theory (DFT) calculations elucidate the source of the variations and the fundamental differences between 2H and 3R stackings. DFT finds larger energies for both A and B excitonic features in 2H than in 3R, consistent with experimental results. In both stacking geometries, the intensity of the dominant A1g Raman mode exhibits significant changes as a function of laser excitation wavelength. These variations in intensity are intimately linked to the stacking- and temperature-dependent optical absorption through resonant enhancement effects. The strongest enhancement is achieved when the laser excitation coincides with the C excitonic feature, leading to the largest Raman intensity under 514 nm excitation in 2H stacking and at 520 nm in 3R stacked WSe2 bilayers.
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24
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Shree S, Lagarde D, Lombez L, Robert C, Balocchi A, Watanabe K, Taniguchi T, Marie X, Gerber IC, Glazov MM, Golub LE, Urbaszek B, Paradisanos I. Interlayer exciton mediated second harmonic generation in bilayer MoS 2. Nat Commun 2021; 12:6894. [PMID: 34824259 PMCID: PMC8617052 DOI: 10.1038/s41467-021-27213-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 11/04/2021] [Indexed: 11/09/2022] Open
Abstract
Second-harmonic generation (SHG) is a non-linear optical process, where two photons coherently combine into one photon of twice their energy. Efficient SHG occurs for crystals with broken inversion symmetry, such as transition metal dichalcogenide monolayers. Here we show tuning of non-linear optical processes in an inversion symmetric crystal. This tunability is based on the unique properties of bilayer MoS2, that shows strong optical oscillator strength for the intra- but also interlayer exciton resonances. As we tune the SHG signal onto these resonances by varying the laser energy, the SHG amplitude is enhanced by several orders of magnitude. In the resonant case the bilayer SHG signal reaches amplitudes comparable to the off-resonant signal from a monolayer. In applied electric fields the interlayer exciton energies can be tuned due to their in-built electric dipole via the Stark effect. As a result the interlayer exciton degeneracy is lifted and the bilayer SHG response is further enhanced by an additional two orders of magnitude, well reproduced by our model calculations. Since interlayer exciton transitions are highly tunable also by choosing twist angle and material combination our results open up new approaches for designing the SHG response of layered materials.
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Affiliation(s)
- Shivangi Shree
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077, Toulouse, France
- Department of Physics, University of Washington, Seattle, WA, USA
| | - Delphine Lagarde
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077, Toulouse, France
| | - Laurent Lombez
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077, Toulouse, France
| | - Cedric Robert
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077, Toulouse, France
| | - Andrea Balocchi
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077, Toulouse, France
| | - 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
| | - Xavier Marie
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077, Toulouse, France
| | - Iann C Gerber
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077, Toulouse, France
| | | | | | - Bernhard Urbaszek
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077, Toulouse, France.
| | - Ioannis Paradisanos
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077, Toulouse, France.
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25
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Ahmad K, Shinde MA, Kim H. Molybdenum disulfide/reduced graphene oxide: Progress in synthesis and electro-catalytic properties for electrochemical sensing and dye sensitized solar cells. Microchem J 2021; 169:106583. [DOI: 10.1016/j.microc.2021.106583] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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26
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Grzeszczyk M, Szpakowski J, Slobodeniuk AO, Kazimierczuk T, Bhatnagar M, Taniguchi T, Watanabe K, Kossacki P, Potemski M, Babiński A, Molas MR. The optical response of artificially twisted MoS[Formula: see text] bilayers. Sci Rep 2021; 11:17037. [PMID: 34426607 PMCID: PMC8382769 DOI: 10.1038/s41598-021-95700-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 07/27/2021] [Indexed: 11/17/2022] Open
Abstract
Two-dimensional layered materials offer the possibility to create artificial vertically stacked structures possessing an additional degree of freedom-the interlayer twist. We present a comprehensive optical study of artificially stacked bilayers (BLs) MoS[Formula: see text] encapsulated in hexagonal BN with interlayer twist angle ranging from 0[Formula: see text] to 60[Formula: see text] using Raman scattering and photoluminescence spectroscopies. It is found that the strength of the interlayer coupling in the studied BLs can be estimated using the energy dependence of indirect emission versus the A[Formula: see text]-E[Formula: see text] energy separation. Due to the hybridization of electronic states in the valence band, the emission line related to the interlayer exciton is apparent in both the natural (2H) and artificial (62[Formula: see text]) MoS[Formula: see text] BLs, while it is absent in the structures with other twist angles. The interlayer coupling energy is estimated to be of about 50 meV. The effect of temperature on energies and intensities of the direct and indirect emission lines in MoS[Formula: see text] BLs is also quantified.
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Affiliation(s)
- M. Grzeszczyk
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - J. Szpakowski
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - A. O. Slobodeniuk
- Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 121 16 Prague 2, Czech Republic
| | - T. Kazimierczuk
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - M. Bhatnagar
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - T. Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044 Japan
| | - K. Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044 Japan
| | - P. Kossacki
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - M. Potemski
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
- Laboratoire National des Champs Magnétiques Intenses, CNRS-UGA-UPS-INSA-EMFL, 25, Avenue des Martyrs, 38042 Grenoble, France
| | - A. Babiński
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - M. R. Molas
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
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27
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Zhang X, Zhou J, Li SQ, Wang Y, Zhang S, Liu Y, Gao J, Zhao J, Wang W, Yu R, Zhang W, Liu N, Nie J, He L, Dou R. Enhanced Valley Polarization of Bilayer MoSe 2 with Variable Stacking Order and Interlayer Coupling. J Phys Chem Lett 2021; 12:5879-5888. [PMID: 34143633 DOI: 10.1021/acs.jpclett.1c01578] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
In two-dimensional transitional metal dichalcogenides, tuning the spin-valley-layer coupling via changing layer numbers and stacking orders remains desirable for their application in valleytronics. Herein, six-point star-like MoSe2 nanoflakes simultaneously containing different atom registration regions from monolayer to bilayer with 2H and 3R stacking order were fabricated, and the valley polarizations were comparably investigated by circular polarized photoluminescent spectroscopy. The degree of valley polarization was detected to be about 12.5% in the monolayer and 10% in the 2H bilayer, but greatly upgraded to about 40% in the 3R bilayer MoSe2. This enhancement was attributed to the multiband spin splitting and generation of spin-dependent layer polarization for the 3R MoSe2 bilayer, which is well evidenced by our ab initio calculations of the energy band structures. Our results demonstrate that preparing TMD crystals with controllable stacking orders and interlayer coupling is a promising route to tune the valley index in TMDs for developing valleytronics technology.
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Affiliation(s)
- Xingli Zhang
- Department of Physics, Beijing Normal University, Beijing 100875, P. R. China
| | - Jun Zhou
- Department of Physics, Beijing Normal University, Beijing 100875, P. R. China
| | - Shi-Qi Li
- Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024, P. R. China
| | - Yuanye Wang
- Department of Physics, Beijing Normal University, Beijing 100875, P. R. China
| | - Shiping Zhang
- Department of Physics, Beijing Normal University, Beijing 100875, P. R. China
| | - Yalin Liu
- Department of Physics, Beijing Normal University, Beijing 100875, P. R. China
| | - Junfeng Gao
- Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024, P. R. China
| | - Jijun Zhao
- Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024, P. R. China
| | - Weipeng Wang
- Beijing National Laboratory for Condensed Mater Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, P. R. China
| | - Richeng Yu
- Beijing National Laboratory for Condensed Mater Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, P. R. China
| | - Weifeng Zhang
- Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
| | - Nan Liu
- Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
| | - Jiacai Nie
- Department of Physics, Beijing Normal University, Beijing 100875, P. R. China
| | - Lin He
- Department of Physics, Beijing Normal University, Beijing 100875, P. R. China
| | - Ruifen Dou
- Department of Physics, Beijing Normal University, Beijing 100875, P. R. China
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28
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Jiang Y, Chen S, Zheng W, Zheng B, Pan A. Interlayer exciton formation, relaxation, and transport in TMD van der Waals heterostructures. Light Sci Appl 2021; 10:72. [PMID: 33811214 PMCID: PMC8018964 DOI: 10.1038/s41377-021-00500-1] [Citation(s) in RCA: 89] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 02/08/2021] [Accepted: 02/24/2021] [Indexed: 05/06/2023]
Abstract
Van der Waals (vdW) heterostructures based on transition metal dichalcogenides (TMDs) generally possess a type-II band alignment that facilitates the formation of interlayer excitons between constituent monolayers. Manipulation of the interlayer excitons in TMD vdW heterostructures holds great promise for the development of excitonic integrated circuits that serve as the counterpart of electronic integrated circuits, which allows the photons and excitons to transform into each other and thus bridges optical communication and signal processing at the integrated circuit. As a consequence, numerous studies have been carried out to obtain deep insight into the physical properties of interlayer excitons, including revealing their ultrafast formation, long population recombination lifetimes, and intriguing spin-valley dynamics. These outstanding properties ensure interlayer excitons with good transport characteristics, and may pave the way for their potential applications in efficient excitonic devices based on TMD vdW heterostructures. At present, a systematic and comprehensive overview of interlayer exciton formation, relaxation, transport, and potential applications is still lacking. In this review, we give a comprehensive description and discussion of these frontier topics for interlayer excitons in TMD vdW heterostructures to provide valuable guidance for researchers in this field.
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Affiliation(s)
- Ying Jiang
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, School of Physics and Electronics, and College of Materials Science and Engineering, Hunan University, Changsha, China
| | - Shula Chen
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, School of Physics and Electronics, and College of Materials Science and Engineering, Hunan University, Changsha, China
- Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, China
| | - Weihao Zheng
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, School of Physics and Electronics, and College of Materials Science and Engineering, Hunan University, Changsha, China
| | - Biyuan Zheng
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, School of Physics and Electronics, and College of Materials Science and Engineering, Hunan University, Changsha, China
| | - Anlian Pan
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, School of Physics and Electronics, and College of Materials Science and Engineering, Hunan University, Changsha, China.
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29
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Abstract
Recent breakthrough in synthesizing arbitrary vertical heterostructures of Ruddlesden–Popper (RP) perovskites opens doors to myriad quantum optoelectronic applications. However, it is not clear whether moiré excitons and flat bands can be formed in such heterostructures. Here, we predict from first principles that twisted homobilayers of RP perovskite, MA2PbI4, can host moiré excitons and yield flat energy bands. The moiré excitons exhibit unique and hybridized characteristics with electrons confined in a single layer of a striped distribution while holes localized in both layers. Nearly flat valence bands can be formed in the bilayers with relatively large twist angles, thanks to the presence of hydrogen bonds that strengthen the interlayer coupling. External pressures can further increase the interlayer coupling, yielding more localized moiré excitons and flatter valence bands. Finally, electrostatic gating is predicted to tune the degree of hybridization, energy, position and localization of moiré excitons in twisted MA2PbI4 bilayers. Excitonic states in twisted MA2PbI4 bilayers were calculated by first-principles calculations.![]()
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Affiliation(s)
- Linghai Zhang
- Department of Physics and Astronomy, California State University Northridge California 91330-8268 USA
| | - Xu Zhang
- Department of Physics and Astronomy, California State University Northridge California 91330-8268 USA
| | - Gang Lu
- Department of Physics and Astronomy, California State University Northridge California 91330-8268 USA
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30
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Sarkar S, Mathew S, Chintalapati S, Rath A, Panahandeh-Fard M, Saha S, Goswami S, Tan SJR, Loh KP, Scott M, Venkatesan T. Direct Bandgap-like Strong Photoluminescence from Twisted Multilayer MoS 2 Grown on SrTiO 3. ACS Nano 2020; 14:16761-16769. [PMID: 33284605 DOI: 10.1021/acsnano.0c04801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
While direct bandgap monolayer 2D transition metal dichalcogenides (TMDs) have emerged as an important optoelectronic material due to strong light-matter interactions, their multilayer counterparts exhibit an indirect bandgap resulting in poor photon emission quantum yield. We report strong direct bandgap-like photoluminescence at ∼1.9 eV from multilayer MoS2 grown on SrTiO3, whose intensity is significantly higher than that observed in multilayer MoS2/SiO2. Using high-resolution electron microscopy we observe interlayer twist and >8% increase in the van der Waals gap, which leads to weaker interlayer coupling. This affects the evolution of the band structure in multilayer MoS2 as probed by transient absorption spectroscopy, causing higher photo carrier recombination at the direct gap. Our results provide a platform that could enable multilayer TMDs for robust optical device applications.
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Affiliation(s)
- Soumya Sarkar
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
| | - Sinu Mathew
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, S.B College, Mahatma Gandhi University, Kerala 686101, India
| | - Sandhya Chintalapati
- Tata Institute for Fundamental Research, Centre for Interdisciplinary Sciences, Hyderabad, 500107, India
| | - Ashutosh Rath
- CSIR-Institute of Minerals and Materials Technology, Bhubaneshwar, Odisha 751013, India
| | | | - Surajit Saha
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, Indian Institute of Science Education and Research, Bhopal 462066, India
| | - Sreetosh Goswami
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Sherman Jun Rong Tan
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
| | - Kian Ping Loh
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
| | - Mary Scott
- Department of Materials Science and Engineering, University of California Berkeley, Berkeley, California 94720, United States
| | - Thirumalai Venkatesan
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore
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31
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Tebyetekerwa M, Zhang J, Xu Z, Truong TN, Yin Z, Lu Y, Ramakrishna S, Macdonald D, Nguyen HT. Mechanisms and Applications of Steady-State Photoluminescence Spectroscopy in Two-Dimensional Transition-Metal Dichalcogenides. ACS Nano 2020; 14:14579-14604. [PMID: 33155803 DOI: 10.1021/acsnano.0c08668] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Two-dimensional (2D) transition-metal dichalcogenide (TMD) semiconductors exhibit many important structural and optoelectronic properties, such as strong light-matter interactions, direct bandgaps tunable from visible to near-infrared regions, flexibility and atomic thickness, quantum-confinement effects, valley polarization possibilities, and so on. Therefore, they are regarded as a very promising class of materials for next-generation state-of-the-art nano/micro optoelectronic devices. To explore different applications and device structures based on 2D TMDs, intrinsic material properties, their relationships, and evolutions with fabrication parameters need to be deeply understood, very often through a combination of various characterization techniques. Among them, steady-state photoluminescence (PL) spectroscopy has been extensively employed. This class of techniques is fast, contactless, and nondestructive and can provide very high spatial resolution. Therefore, it can be used to obtain optoelectronic properties from samples of various sizes (from microns to centimeters) during the fabrication process without complex sample preparation. In this article, the mechanism and applications of steady-state PL spectroscopy in 2D TMDs are reviewed. The first part of this review details the physics of PL phenomena in semiconductors and common techniques to acquire and analyze PL spectra. The second part introduces various applications of PL spectroscopy in 2D TMDs. Finally, a broader perspective is discussed to highlight some limitations and untapped opportunities of PL spectroscopy in characterizing 2D TMDs.
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Affiliation(s)
- Mike Tebyetekerwa
- Research School of Electrical, Energy, and Materials Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Jian Zhang
- Research School of Electrical, Energy, and Materials Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Zhen Xu
- Department of Chemical Engineering, Imperial College London, London SW7 2AZ, United Kingdom
| | - Thien N Truong
- Research School of Electrical, Energy, and Materials Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Zongyou Yin
- Research School of Chemistry, College of Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Yuerui Lu
- Research School of Electrical, Energy, and Materials Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Seeram Ramakrishna
- Department of Mechanical Engineering, National University of Singapore, Singapore 119260, Singapore
| | - Daniel Macdonald
- Research School of Electrical, Energy, and Materials Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Hieu T Nguyen
- Research School of Electrical, Energy, and Materials Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
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32
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Wei J, Huang JK, Du J, Bian B, Li S, Wang D. Effect of the geometry of precursor crucibles on the growth of MoS 2 flakes by chemical vapor deposition. NEW J CHEM 2020. [DOI: 10.1039/d0nj05486k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Chemical vapor deposition (CVD) employing a furnace with multiple temperature zones is still the best and most widely used method for preparing high-quality MoS2 flakes.
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Affiliation(s)
- Jinlei Wei
- School of Science, Jiangnan University
- Wuxi 214122
- China
- School of Materials Science and Engineering, The University of New South Wales
- Sydney
| | - Jing-Kai Huang
- School of Materials Science and Engineering, The University of New South Wales
- Sydney
- Australia
| | - Jianhao Du
- School of Materials Science and Engineering, The University of New South Wales
- Sydney
- Australia
| | - Baoan Bian
- School of Science, Jiangnan University
- Wuxi 214122
- China
| | - Sean Li
- School of Materials Science and Engineering, The University of New South Wales
- Sydney
- Australia
| | - Danyang Wang
- School of Materials Science and Engineering, The University of New South Wales
- Sydney
- Australia
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