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Kinoshita K, Lin YC, Moriya R, Okazaki S, Onodera M, Zhang Y, Senga R, Watanabe K, Taniguchi T, Sasagawa T, Suenaga K, Machida T. Crossover between rigid and reconstructed moiré lattice in h-BN-encapsulated twisted bilayer WSe 2 with different twist angles. NANOSCALE 2024; 16:14358-14365. [PMID: 38953240 DOI: 10.1039/d4nr01863j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/03/2024]
Abstract
A moiré lattice in a twisted-bilayer transition metal dichalcogenide (tBL-TMD) exhibits a complex atomic reconstruction effect when its twist angle is less than a few degrees. The influence of the atomic reconstruction on material properties of the tBL-TMD has been of particular interest. In this study, we performed scanning transmission electron microscopy (STEM) imaging of a moiré lattice in h-BN-encapsulated twisted bilayer WSe2 with various twist angles. Atomic-resolution imaging of the moiré lattice revealed a reconstructed moiré lattice below a crossover twist angle of ∼4° and a rigid moiré lattice above this angle. Our findings indicate that h-BN encapsulation has a considerable influence on lattice reconstruction, as the crossover twist angle was larger in h-BN-encapsulated devices compared to non-encapsulated devices. We believe that this difference is due to the improved flatness and uniformity of the twisted bilayers with h-BN encapsulation. Our results provide a foundation for a deeper understanding of the lattice reconstruction in twisted TMD materials with h-BN encapsulation.
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Affiliation(s)
- Kei Kinoshita
- Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505, Japan.
| | - Yung-Chang Lin
- National Institute of Advanced Industrial Science and Technology, 1-1-1 Higashi, Tsukuba 305-8565, Japan
| | - Rai Moriya
- Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505, Japan.
| | - Shota Okazaki
- Laboratory for Materials and Structures, Tokyo Institute of Technology, 4259 Nagatsuta, Yokohama, Kanagawa 226-8501, Japan
| | - Momoko Onodera
- Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505, Japan.
| | - Yijin Zhang
- Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505, Japan.
| | - Ryosuke Senga
- National Institute of Advanced Industrial Science and Technology, 1-1-1 Higashi, Tsukuba 305-8565, Japan
| | - 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
| | - Takao Sasagawa
- Laboratory for Materials and Structures, Tokyo Institute of Technology, 4259 Nagatsuta, Yokohama, Kanagawa 226-8501, Japan
| | - Kazu Suenaga
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - Tomoki Machida
- Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505, Japan.
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Soltero I, Kaliteevski MA, McHugh JG, Enaldiev V, Fal’ko VI. Competition of Moiré Network Sites to Form Electronic Quantum Dots in Reconstructed MoX 2/WX 2 Heterostructures. NANO LETTERS 2024; 24:1996-2002. [PMID: 38295286 PMCID: PMC10870774 DOI: 10.1021/acs.nanolett.3c04427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 01/26/2024] [Accepted: 01/26/2024] [Indexed: 02/02/2024]
Abstract
Twisted bilayers of two-dimensional semiconductors offer a versatile platform for engineering quantum states for charge carriers using moiré superlattice effects. Among the systems of recent interest are twistronic MoX2/WX2 heterostructures (X = Se or S), which undergo reconstruction into preferential stacking domains and highly strained domain wall networks, determining the electron/hole localization across moiré superlattices. Here, we present a catalogue of options for the formation of self-organized quantum dots and wires in lattice-reconstructed marginally twisted MoX2/WX2 bilayers with a relative lattice mismatch δ ≪ 1 for twist angles ranging from perfect alignment to θ ∼ 1°. On the basis of multiscale modeling taking into account twirling of domain wall networks, we analyze bilayers with both parallel and antiparallel orientations of their unit cells and describe crossovers between different positioning of band edges for electrons and holes across moiré superlattices when θ < δ and θ > δ.
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Affiliation(s)
- Isaac Soltero
- Department
of Physics and Astronomy, University of
Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
- National
Graphene Institute, University of Manchester, Booth Street East, Manchester M13 9PL, United Kingdom
| | - Mikhail A. Kaliteevski
- Department
of Physics and Astronomy, University of
Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
- National
Graphene Institute, University of Manchester, Booth Street East, Manchester M13 9PL, United Kingdom
| | - James G. McHugh
- Department
of Physics and Astronomy, University of
Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
- National
Graphene Institute, University of Manchester, Booth Street East, Manchester M13 9PL, United Kingdom
| | - Vladimir Enaldiev
- Department
of Physics and Astronomy, University of
Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
- National
Graphene Institute, University of Manchester, Booth Street East, Manchester M13 9PL, United Kingdom
| | - Vladimir I. Fal’ko
- Department
of Physics and Astronomy, University of
Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
- National
Graphene Institute, University of Manchester, Booth Street East, Manchester M13 9PL, United Kingdom
- Henry
Royce Institute for Advanced Materials, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
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