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Chatterjee S, Dandu M, Dasika P, Biswas R, Das S, Watanabe K, Taniguchi T, Raghunathan V, Majumdar K. Harmonic to anharmonic tuning of moiré potential leading to unconventional Stark effect and giant dipolar repulsion in WS 2/WSe 2 heterobilayer. Nat Commun 2023; 14:4679. [PMID: 37542024 PMCID: PMC10403536 DOI: 10.1038/s41467-023-40329-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 07/24/2023] [Indexed: 08/06/2023] Open
Abstract
Excitonic states trapped in harmonic moiré wells of twisted heterobilayers is an intriguing testbed for exploring many-body physics. However, the moiré potential is primarily governed by the twist angle, and its dynamic tuning remains a challenge. Here we demonstrate anharmonic tuning of moiré potential in a WS2/WSe2 heterobilayer through gate voltage and optical power. A gate voltage can result in a local in-plane perturbing field with odd parity around the high-symmetry points. This allows us to simultaneously observe the first (linear) and second (parabolic) order Stark shift for the ground state and first excited state, respectively, of the moiré trapped exciton - an effect opposite to conventional quantum-confined Stark shift. Depending on the degree of confinement, these excitons exhibit up to twenty-fold gate-tunability in the lifetime (100 to 5 ns). Also, exciton localization dependent dipolar repulsion leads to an optical power-induced blueshift of ~ 1 meV/μW - a five-fold enhancement over previous reports.
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Affiliation(s)
- Suman Chatterjee
- Department of Electrical Communication Engineering, Indian Institute of Science, Bangalore, 560012, India
| | - Medha Dandu
- Department of Electrical Communication Engineering, Indian Institute of Science, Bangalore, 560012, India
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Pushkar Dasika
- Department of Electrical Communication Engineering, Indian Institute of Science, Bangalore, 560012, India
| | - Rabindra Biswas
- Department of Electrical Communication Engineering, Indian Institute of Science, Bangalore, 560012, India
| | - Sarthak Das
- Department of Electrical Communication Engineering, Indian Institute of Science, Bangalore, 560012, India
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), Singapore, 138634, Republic of Singapore
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-044, Japan
| | - Varun Raghunathan
- Department of Electrical Communication Engineering, Indian Institute of Science, Bangalore, 560012, India
| | - Kausik Majumdar
- Department of Electrical Communication Engineering, Indian Institute of Science, Bangalore, 560012, India.
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2
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Zhu B, Xiao K, Yang S, Watanabe K, Taniguchi T, Cui X. In-Plane Electric-Field-Induced Orbital Hybridization of Excitonic States in Monolayer WSe_{2}. Phys Rev Lett 2023; 131:036901. [PMID: 37540882 DOI: 10.1103/physrevlett.131.036901] [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] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 05/06/2023] [Accepted: 06/06/2023] [Indexed: 08/06/2023]
Abstract
The giant exciton binding energy and the richness of degrees of freedom make monolayer transition metal dichalcogenide an unprecedented playground for exploring exciton physics in 2D systems. Thanks to the well-energetically separated excitonic states, the response of the discrete excitonic states to the electric field could be precisely examined. Here we utilize the photocurrent spectroscopy to probe excitonic states under a static in-plane electric field. We demonstrate that the in-plane electric field leads to a significant orbital hybridization of Rydberg excitonic states with different angular momentum (especially orbital hybridization of 2s and 2p) and, consequently, optically actives 2p-state exciton. Besides, the electric-field controlled mixing of the high lying exciton state and continuum band enhances the oscillator strength of the discrete excited exciton states. This electric field modulation of the excitonic states in monolayer TMDs provides a paradigm of the manipulation of 2D excitons for potential applications of the electro-optical modulation in 2D semiconductors.
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Affiliation(s)
- Bairen Zhu
- Key Laboratory of Quantum Precision Measurement of Zhejiang Province, Department of Applied Physics, Zhejiang University of Technology, Hangzhou 310023, China
| | - Ke Xiao
- Physics Department, University of Hong Kong, Hong Kong, China
| | - Siyuan Yang
- Physics Department, University of Hong Kong, Hong Kong, China
| | - 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
| | - Xiaodong Cui
- Physics Department, University of Hong Kong, Hong Kong, China
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3
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Lau CS, Das S, Verzhbitskiy IA, Huang D, Zhang Y, Talha-Dean T, Fu W, Venkatakrishnarao D, Johnson Goh KE. Dielectrics for Two-Dimensional Transition-Metal Dichalcogenide Applications. ACS Nano 2023. [PMID: 37257134 DOI: 10.1021/acsnano.3c03455] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Despite over a decade of intense research efforts, the full potential of two-dimensional transition-metal dichalcogenides continues to be limited by major challenges. The lack of compatible and scalable dielectric materials and integration techniques restrict device performances and their commercial applications. Conventional dielectric integration techniques for bulk semiconductors are difficult to adapt for atomically thin two-dimensional materials. This review provides a brief introduction into various common and emerging dielectric synthesis and integration techniques and discusses their applicability for 2D transition metal dichalcogenides. Dielectric integration for various applications is reviewed in subsequent sections including nanoelectronics, optoelectronics, flexible electronics, valleytronics, biosensing, quantum information processing, and quantum sensing. For each application, we introduce basic device working principles, discuss the specific dielectric requirements, review current progress, present key challenges, and offer insights into future prospects and opportunities.
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Affiliation(s)
- Chit Siong Lau
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis #08-03, Singapore 138634, Republic of Singapore
| | - Sarthak Das
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis #08-03, Singapore 138634, Republic of Singapore
| | - Ivan A Verzhbitskiy
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis #08-03, Singapore 138634, Republic of Singapore
| | - Ding Huang
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis #08-03, Singapore 138634, Republic of Singapore
| | - Yiyu Zhang
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis #08-03, Singapore 138634, Republic of Singapore
| | - Teymour Talha-Dean
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis #08-03, Singapore 138634, Republic of Singapore
- Department of Physics and Astronomy, Queen Mary University of London, London E1 4NS, United Kingdom
| | - Wei Fu
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis #08-03, Singapore 138634, Republic of Singapore
| | - Dasari Venkatakrishnarao
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis #08-03, Singapore 138634, Republic of Singapore
| | - Kuan Eng Johnson Goh
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis #08-03, Singapore 138634, Republic of Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117551, Singapore
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 50 Nanyang Avenue 639798, Singapore
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4
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Eghbali A, Vyshnevyy AA, Arsenin AV, Volkov VS. Optical Anisotropy and Excitons in MoS 2 Interfaces for Sensitive Surface Plasmon Resonance Biosensors. Biosensors (Basel) 2022; 12:582. [PMID: 36004977 PMCID: PMC9405904 DOI: 10.3390/bios12080582] [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] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 07/26/2022] [Accepted: 07/27/2022] [Indexed: 06/15/2023]
Abstract
The use of ultra-thin spacer layers above metal has become a popular approach to the enhancement of optical sensitivity and immobilization efficiency of label-free SPR sensors. At the same time, the giant optical anisotropy inherent to transition metal dichalcogenides may significantly affect characteristics of the studied sensors. Here, we present a systematic study of the optical sensitivity of an SPR biosensor platform with auxiliary layers of MoS2. By performing the analysis in a broad spectral range, we reveal the effect of exciton-driven dielectric response of MoS2 and its anisotropy on the sensitivity characteristics. The excitons are responsible for the decrease in the optimal thickness of MoS2. Furthermore, despite the anisotropy being at record height, it affects the sensitivity only slightly, although the effect becomes stronger in the near-infrared spectral range, where it may lead to considerable change in the optimal design of the biosensor.
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Wu Y, He J, Chen Y, Kong M, Zhang Y, Hu X, Lian J, Zhang H, Zhang R. Excellent response to near ultraviolet light and large intervalley scatterings of electrons in 2D SnS 2. Nanoscale 2022; 14:5462-5471. [PMID: 35322849 DOI: 10.1039/d2nr00416j] [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] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Tin disulfide (SnS2) has attracted much attention as a novel two dimensional material due to its potential applications in electronics and optoelectronics. In this work, we investigated the optical properties of ultra-thin SnS2 film samples (∼8 nm) via spectroscopic ellipsometry, and found that SnS2 maintains a relatively high imaginary part of the dielectric constant (ε2) in the range of 256-377 nm indicating high optical response. The carrier transport properties of SnS2 were investigated considering full mode-resolved electron-phonon couplings, which reveal that the intervalley scatterings between degenerate valley (peaks) states via the fifth optical branch phonons play a dominant role in electron scattering, while ZA phonons dominate the hole scattering. The calculated electron mobility is ∼50 cm2 V-1 s-1 which is close to previously reported experimental results. By considering full el-ph interactions based on the rigid-band approximation, the maximum value of the thermoelectric figure of merit zT reaches 0.43 at 700 K. Our work not only reveals the promising applications of SnS2 in the fields of electronics and optoelectronics, but also showcases the computational framework for precise calculations of thermoelectric performances.
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Affiliation(s)
- Yu Wu
- Key Laboratory of Micro and Nano Photonic Structures (MOE) and Department of Optical Science and Engineering, Fudan University, Shanghai 200433, China.
| | - Junbo He
- Key Laboratory of Micro and Nano Photonic Structures (MOE) and Department of Optical Science and Engineering, Fudan University, Shanghai 200433, China.
| | - Ying Chen
- Department of Light Sources and Illuminating Engineering, Fudan University, Shanghai 200433, China
| | - Mingran Kong
- Key Laboratory of Micro and Nano Photonic Structures (MOE) and Department of Optical Science and Engineering, Fudan University, Shanghai 200433, China.
| | - Yiming Zhang
- Key Laboratory of Micro and Nano Photonic Structures (MOE) and Department of Optical Science and Engineering, Fudan University, Shanghai 200433, China.
| | - Xiaobing Hu
- Stare Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai 200433, China
| | - Jianwei Lian
- Stare Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai 200433, China
| | - Hao Zhang
- Key Laboratory of Micro and Nano Photonic Structures (MOE) and Department of Optical Science and Engineering, Fudan University, Shanghai 200433, China.
- Yiwu Research Institute of Fudan University, Chengbei Road, Yiwu City, Zhejiang 322000, China
- Nanjing University, National Laboratory of Solid State Microstructure, Nanjing 210093, China
| | - Rongjun Zhang
- Key Laboratory of Micro and Nano Photonic Structures (MOE) and Department of Optical Science and Engineering, Fudan University, Shanghai 200433, China.
- Academy for Engineering & Technology, Fudan University, Shanghai, 200433, China.
- Yiwu Research Institute of Fudan University, Chengbei Road, Yiwu City, Zhejiang 322000, China
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6
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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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7
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Peimyoo N, Deilmann T, Withers F, Escolar J, Nutting D, Taniguchi T, Watanabe K, Taghizadeh A, Craciun MF, Thygesen KS, Russo S. Electrical tuning of optically active interlayer excitons in bilayer MoS 2. Nat Nanotechnol 2021; 16:888-893. [PMID: 34083771 DOI: 10.1038/s41565-021-00916-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 04/19/2021] [Indexed: 06/12/2023]
Abstract
Interlayer (IL) excitons, comprising electrons and holes residing in different layers of van der Waals bonded two-dimensional semiconductors, have opened new opportunities for room-temperature excitonic devices. So far, two-dimensional IL excitons have been realized in heterobilayers with type-II band alignment. However, the small oscillator strength of the resulting IL excitons and difficulties with producing heterostructures with definite crystal orientation over large areas have challenged the practical applicability of this design. Here, following the theoretical prediction and recent experimental confirmation of the existence of IL excitons in bilayer MoS2, we demonstrate the electrical control of such excitons up to room temperature. We find that the IL excitonic states preserve their large oscillator strength as their energies are manipulated by the electric field. We attribute this effect to the mixing of the pure IL excitons with intralayer excitons localized in a single layer. By applying an electric field perpendicular to the bilayer MoS2 crystal plane, excitons with IL character split into two peaks with an X-shaped field dependence as a clear fingerprint of the shift of the monolayer bands with respect to each other. Finally, we demonstrate the full control of the energies of IL excitons distributed homogeneously over a large area of our device.
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Affiliation(s)
- Namphung Peimyoo
- Centre for Graphene Science, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK
| | - Thorsten Deilmann
- Institut für Festkörpertheorie, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Freddie Withers
- Centre for Graphene Science, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK
| | - Janire Escolar
- Centre for Graphene Science, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK
| | - Darren Nutting
- Centre for Graphene Science, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Kenji Watanabe
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Alireza Taghizadeh
- Department of Materials and Production, Aalborg University, Aalborg, Denmark
- CAMD, Department of Physics, Technical University of Denmark, Kongens Lyngby, Denmark
- Center for Nanostructured Graphene (CNG), Department of Physics, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Monica Felicia Craciun
- Centre for Graphene Science, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK
| | - Kristian Sommer Thygesen
- CAMD, Department of Physics, Technical University of Denmark, Kongens Lyngby, Denmark
- Center for Nanostructured Graphene (CNG), Department of Physics, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Saverio Russo
- Centre for Graphene Science, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK.
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Datta K, Li Z, Lyu Z, Deotare PB. Piezoelectric Modulation of Excitonic Properties in Monolayer WSe 2 under Strong Dielectric Screening. ACS Nano 2021; 15:12334-12341. [PMID: 34181857 DOI: 10.1021/acsnano.1c04269] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We investigate the interaction of excitons in monolayer WSe2 with the piezoelectric field of surface acoustic wave (SAW) at room temperature using photoluminescence (PL) spectroscopy and report a large in-plane exciton polarizability of 8.43 ± 0.18 × 10-6 Dm/V. Such large polarizability arises due to the strong dielectric screening from the piezoelectric substrate. In addition, we show that the exciton-piezoelectric field interaction and population distribution between neutral excitons and trions can be optically manipulated by controlling the field screening using photogenerated free carriers. Finally, we model the broadening of the exciton PL line width and report that the interaction is dominated by type-II band edge modulation, because of the in-plane electric field in the system. The results help understand the interaction of excitons in monolayer transition-metal dichalcogenides that will aid in controlled manipulation of excitonic properties for applications in sensing, detection, and on-chip communication.
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Affiliation(s)
- Kanak Datta
- Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Zidong Li
- Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Zhengyang Lyu
- Applied Physics Program, University of Michigan Ann Arbor, Michigan 48109, United States
| | - Parag B Deotare
- Applied Physics Program, University of Michigan Ann Arbor, Michigan 48109, United States
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Leisgang N, Shree S, Paradisanos I, Sponfeldner L, Robert C, Lagarde D, Balocchi A, Watanabe K, Taniguchi T, Marie X, Warburton RJ, Gerber IC, Urbaszek B. Giant Stark splitting of an exciton in bilayer MoS 2. Nat Nanotechnol 2020; 15:901-907. [PMID: 32778806 DOI: 10.1038/s41565-020-0750-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 07/06/2020] [Indexed: 06/11/2023]
Abstract
Transition metal dichalcogenides (TMDs) constitute a versatile platform for atomically thin optoelectronics devices and spin-valley memory applications. In monolayer TMDs the optical absorption is strong, but the transition energy cannot be tuned as the neutral exciton has essentially no out-of-plane static electric dipole1,2. In contrast, interlayer exciton transitions in heterobilayers are widely tunable in applied electric fields, but their coupling to light is substantially reduced. In this work, we show tuning over 120 meV of interlayer excitons with a high oscillator strength in bilayer MoS2 due to the quantum-confined Stark effect3. We optically probed the interaction between intra- and interlayer excitons as they were energetically tuned into resonance. Interlayer excitons interact strongly with intralayer B excitons, as demonstrated by a clear avoided crossing, whereas the interaction with intralayer A excitons is substantially weaker. Our observations are supported by density functional theory (DFT) calculations, which include excitonic effects. In MoS2 trilayers, our experiments uncovered two types of interlayer excitons with and without in-built electric dipoles. Highly tunable excitonic transitions with large in-built dipoles and oscillator strengths will result in strong exciton-exciton interactions and therefore hold great promise for non-linear optics with polaritons.
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Affiliation(s)
- Nadine Leisgang
- Department of Physics, University of Basel, Basel, Switzerland
| | - Shivangi Shree
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, Toulouse, France
| | | | | | - Cedric Robert
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, Toulouse, France
| | | | - Andrea Balocchi
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, Toulouse, France
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Ibaraki, Japan
| | - Takashi Taniguchi
- International Center for Materials Anorthite, National Institute for Materials Science, Ibaraki, Japan
| | - Xavier Marie
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, Toulouse, France
| | | | - Iann C Gerber
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, Toulouse, France
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10
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Tian T, Scullion D, Hughes D, Li LH, Shih CJ, Coleman J, Chhowalla M, Santos EJG. Electronic Polarizability as the Fundamental Variable in the Dielectric Properties of Two-Dimensional Materials. Nano Lett 2020; 20:841-851. [PMID: 31888332 DOI: 10.1021/acs.nanolett.9b02982] [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: 05/27/2023]
Abstract
The dielectric constant, which defines the polarization of the media, is a key quantity in condensed matter. It determines several electronic and optoelectronic properties important for a plethora of modern technologies from computer memory to field effect transistors and communication circuits. Moreover, the importance of the dielectric constant in describing electromagnetic interactions through screening plays a critical role in understanding fundamental molecular interactions. Here, we show that despite its fundamental transcendence, the dielectric constant does not define unequivocally the dielectric properties of two-dimensional (2D) materials due to the locality of their electrostatic screening. Instead, the electronic polarizability correctly captures the dielectric nature of a 2D material which is united to other physical quantities in an atomically thin layer. We reveal a long-sought universal formalism where electronic, geometrical, and dielectric properties are intrinsically correlated through the polarizability, opening the door to probe quantities yet not directly measurable including the real covalent thickness of a layer. We unify the concept of dielectric properties in any material dimension finding a global dielectric anisotropy index defining their controllability through dimensionality.
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Affiliation(s)
- Tian Tian
- Institute for Chemical and Bioengineering , ETH Zürich , Vladimir Prelog Weg 1 , CH-8093 Zürich , Switzerland
| | - Declan Scullion
- School of Mathematics and Physics , Queen's University , Belfast BT7 1NN , United Kingdom
| | - Dale Hughes
- School of Mathematics and Physics , Queen's University , Belfast BT7 1NN , United Kingdom
| | - Lu Hua Li
- Institute for Frontier Materials , Deakin University , Waurn Ponds, Victoria 3216 , Australia
| | - Chih-Jen Shih
- Institute for Chemical and Bioengineering , ETH Zürich , Vladimir Prelog Weg 1 , CH-8093 Zürich , Switzerland
| | - Jonathan Coleman
- School of Physics, Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN) and Advanced Materials and BioEngineering Research (AMBER) , Trinity College Dublin , Dublin 2, Ireland
| | - Manish Chhowalla
- Department of Materials Science and Metallurgy , University of Cambridge , Cambridge CB3 0FS , United Kingdom
| | - Elton J G Santos
- School of Mathematics and Physics , Queen's University , Belfast BT7 1NN , United Kingdom
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11
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Wang J, Lin F, Verzhbitskiy I, Watanabe K, Taniguchi T, Martin J, Eda G. Polarity Tunable Trionic Electroluminescence in Monolayer WSe 2. Nano Lett 2019; 19:7470-7475. [PMID: 31517494 DOI: 10.1021/acs.nanolett.9b03215] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Monolayer WSe2 exhibits luminescence arising from various types of exciton complexes due to strong many-body effects. Here, we demonstrate selective electrical excitation of positive and negative trions in van der Waals metal-insulator-semiconductor (MIS) heterostructure consisting of few-layer graphene (FLG), hexagonal boron nitride (hBN), and monolayer WSe2. Intentional unbalanced injection of electrons and holes is achieved via field-emission tunneling and electrostatic accumulation. The device exhibits planar electroluminescence from either positive trion X+ or negative trion X- depending on the bias conditions. We show that hBN serves as a tunneling barrier material allowing selective injection of electron or holes into WSe2 from FLG layer. Our observation offers prospects for hot carrier injection, trion manipulation, and on-chip excitonic devices based on two-dimensional semiconductors.
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Affiliation(s)
- Junyong Wang
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542
- Centre for Advanced 2D Materials , National University of Singapore , 6 Science Drive 2 , Singapore 117546
| | - Fanrong Lin
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542
- Centre for Advanced 2D Materials , National University of Singapore , 6 Science Drive 2 , Singapore 117546
| | - Ivan Verzhbitskiy
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542
- Centre for Advanced 2D Materials , National University of Singapore , 6 Science Drive 2 , Singapore 117546
| | - Kenji Watanabe
- National Institute for Material Science , 1-1 Namiki , Tsukuba 305-0044 , Japan
| | - Takashi Taniguchi
- National Institute for Material Science , 1-1 Namiki , Tsukuba 305-0044 , Japan
| | - Jens Martin
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542
- Centre for Advanced 2D Materials , National University of Singapore , 6 Science Drive 2 , Singapore 117546
| | - Goki Eda
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542
- Centre for Advanced 2D Materials , National University of Singapore , 6 Science Drive 2 , Singapore 117546
- Department of Chemistry , National University of Singapore , 3 Science Drive 3 , Singapore 117543
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