1
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Graham AJ, Park H, Nguyen PV, Nunn J, Kandyba V, Cattelan M, Giampietri A, Barinov A, Watanabe K, Taniguchi T, Andreev A, Rudner M, Xu X, Wilson NR, Cobden DH. Conduction Band Replicas in a 2D Moiré Semiconductor Heterobilayer. NANO LETTERS 2024; 24:5117-5124. [PMID: 38629940 DOI: 10.1021/acs.nanolett.3c04866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
Stacking monolayer semiconductors creates moiré patterns, leading to correlated and topological electronic phenomena, but measurements of the electronic structure underpinning these phenomena are scarce. Here, we investigate the properties of the conduction band in moiré heterobilayers of WS2/WSe2 using submicrometer angle-resolved photoemission spectroscopy with electrostatic gating. We find that at all twist angles the conduction band edge is the K-point valley of the WS2, with a band gap of 1.58 ± 0.03 eV. From the resolved conduction band dispersion, we deduce an effective mass of 0.15 ± 0.02 me. Additionally, we observe replicas of the conduction band displaced by reciprocal lattice vectors of the moiré superlattice. We argue that the replicas result from the moiré potential modifying the conduction band states rather than final-state diffraction. Interestingly, the replicas display an intensity pattern with reduced 3-fold symmetry, which we show implicates the pseudo vector potential associated with in-plane strain in moiré band formation.
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Affiliation(s)
- Abigail J Graham
- Department of Physics, University of Warwick, Coventry CV4 7AL, U.K
| | - Heonjoon Park
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
| | - Paul V Nguyen
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
| | - James Nunn
- Department of Physics, University of Warwick, Coventry CV4 7AL, U.K
| | - Viktor Kandyba
- Elettra - Sincrotrone Trieste, S.C.p.A, Basovizza (TS), Friuli-Venezia Giulia 34149, Italy
| | - Mattia Cattelan
- Elettra - Sincrotrone Trieste, S.C.p.A, Basovizza (TS), Friuli-Venezia Giulia 34149, Italy
| | - Alessio Giampietri
- Elettra - Sincrotrone Trieste, S.C.p.A, Basovizza (TS), Friuli-Venezia Giulia 34149, Italy
| | - Alexei Barinov
- Elettra - Sincrotrone Trieste, S.C.p.A, Basovizza (TS), Friuli-Venezia Giulia 34149, Italy
| | - 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
| | - Anton Andreev
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
| | - Mark Rudner
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
| | - Xiaodong Xu
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
- Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, United States
| | - Neil R Wilson
- Department of Physics, University of Warwick, Coventry CV4 7AL, U.K
| | - David H Cobden
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
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2
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Li Y, Wan Q, Xu N. Recent Advances in Moiré Superlattice Systems by Angle-Resolved Photoemission Spectroscopy. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023:e2305175. [PMID: 37689836 DOI: 10.1002/adma.202305175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 08/16/2023] [Indexed: 09/11/2023]
Abstract
The last decade has witnessed a flourish in 2D materials including graphene and transition metal dichalcogenides (TMDs) as atomic-scale Legos. Artificial moiré superlattices via stacking 2D materials with a twist angle and/or a lattice mismatch have recently become a fertile playground exhibiting a plethora of emergent properties beyond their building blocks. These rich quantum phenomena stem from their nontrivial electronic structures that are effectively tuned by the moiré periodicity. Modern angle-resolved photoemission spectroscopy (ARPES) can directly visualize electronic structures with decent momentum, energy, and spatial resolution, thus can provide enlightening insights into fundamental physics in moiré superlattice systems and guides for designing novel devices. In this review, first, a brief introduction is given on advanced ARPES techniques and basic ideas of band structures in a moiré superlattice system. Then ARPES research results of various moiré superlattice systems are highlighted, including graphene on substrates with small lattice mismatches, twisted graphene/TMD moiré systems, and high-order moiré superlattice systems. Finally, it discusses important questions that remain open, challenges in current experimental investigations, and presents an outlook on this field of research.
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Affiliation(s)
- Yiwei Li
- Institute for Advanced Studies (IAS), Wuhan University, Wuhan, 430072, China
| | - Qiang Wan
- Institute for Advanced Studies (IAS), Wuhan University, Wuhan, 430072, China
| | - Nan Xu
- Institute for Advanced Studies (IAS), Wuhan University, Wuhan, 430072, China
- Wuhan Institute of Quantum Technology, Wuhan, 430206, China
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3
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Wang Q, Song Z, Tao J, Jin H, Li S, Wang Y, Liu X, Zhang L. Interface contact and modulated electronic properties by in-plain strains in a graphene-MoS 2 heterostructure. RSC Adv 2023; 13:2903-2911. [PMID: 36756432 PMCID: PMC9850458 DOI: 10.1039/d2ra07949f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 01/10/2023] [Indexed: 01/21/2023] Open
Abstract
Designing a specific heterojunction by assembling suitable two-dimensional (2D) semiconductors has shown significant potential in next-generation micro-nano electronic devices. In this paper, we study the structural and electronic properties of graphene-MoS2 (Gr-MoS2) heterostructures with in-plain biaxial strain using density functional theory. It is found that the interaction between graphene and monolayer MoS2 is characterized by a weak van der Waals interlayer coupling with the stable layer spacing of 3.39 Å and binding energy of 0.35 J m-2. In the presence of MoS2, the linear bands on the Dirac cone of graphene are slightly split. A tiny band gap about 1.2 meV opens in the Gr-MoS2 heterojunction due to the breaking of sublattice symmetry, and it could be effectively modulated by strain. Furthermore, an n-type Schottky contact is formed at the Gr-MoS2 interface with a Schottky barrier height of 0.33 eV, which can be effectively modulated by in-plane strain. Especially, an n-type ohmic contact is obtained when 6% tensile strain is imposed. The appearance of the non-zero band gap in graphene has opened up new possibilities for its application and the ohmic contact predicts the Gr-MoS2 van der Waals heterojunction nanocomposite as a competitive candidate in next-generation optoelectronics and Schottky devices.
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Affiliation(s)
- Qian Wang
- School of Physics and Mechanical & Electrical Engineering, Hubei Engineering Technology Research Center of Environmental Purification Materials, Hubei University of Education Wuhan 430000 China
| | - Zhenjun Song
- School of Parmaceutical and Materials Engineering, Taizhou UniversityTaizhou 318000PR China
| | - Junhui Tao
- School of Physics and Mechanical & Electrical Engineering, Hubei Engineering Technology Research Center of Environmental Purification Materials, Hubei University of Education Wuhan 430000 China
| | - Haiqin Jin
- School of Physics and Mechanical & Electrical Engineering, Hubei Engineering Technology Research Center of Environmental Purification Materials, Hubei University of Education Wuhan 430000 China
| | - Sha Li
- School of Physics and Mechanical & Electrical Engineering, Hubei Engineering Technology Research Center of Environmental Purification Materials, Hubei University of Education Wuhan 430000 China
| | - Yuran Wang
- School of Physics and Mechanical & Electrical Engineering, Hubei Engineering Technology Research Center of Environmental Purification Materials, Hubei University of Education Wuhan 430000 China
| | - Xuejuan Liu
- College of Physics and Engineering, Chengdu Normal UniversityChengdu 611130China
| | - Lin Zhang
- School of Physics and Mechanical & Electrical Engineering, Hubei Engineering Technology Research Center of Environmental Purification Materials, Hubei University of Education Wuhan 430000 China
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4
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Iordanidou K, Mitra R, Shetty N, Lara-Avila S, Dash S, Kubatkin S, Wiktor J. Electric Field and Strain Tuning of 2D Semiconductor van der Waals Heterostructures for Tunnel Field-Effect Transistors. ACS APPLIED MATERIALS & INTERFACES 2023; 15:1762-1771. [PMID: 36537996 PMCID: PMC9837817 DOI: 10.1021/acsami.2c13151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 11/21/2022] [Indexed: 06/17/2023]
Abstract
Heterostacks consisting of low-dimensional materials are attractive candidates for future electronic nanodevices in the post-silicon era. In this paper, using first-principles calculations based on density functional theory (DFT), we explore the structural and electronic properties of MoTe2/ZrS2 heterostructures with various stacking patterns and thicknesses. Our simulations show that the valence band (VB) edge of MoTe2 is almost aligned with the conduction band (CB) edge of ZrS2, and (MoTe2)m/(ZrS2)m (m = 1, 2) heterostructures exhibit the long-sought broken gap band alignment, which is pivotal for realizing tunneling transistors. Electrons are found to spontaneously flow from MoTe2 to ZrS2, and the system resembles an ultrascaled parallel plate capacitor with an intrinsic electric field pointed from MoTe2 to ZrS2. The effects of strain and external electric fields on the electronic properties are also investigated. For vertical compressive strains, the charge transfer increases due to the decreased coupling between the layers, whereas tensile strains lead to the opposite behavior. For negative electric fields a transition from the type-III to the type-II band alignment is induced. In contrast, by increasing the positive electric fields, a larger overlap between the valence and conduction bands is observed, leading to a larger band-to-band tunneling (BTBT) current. Low-strained heterostructures with various rotation angles between the constituent layers are also considered. We find only small variations in the energies of the VB and CB edges with respect to the Fermi level, for different rotation angles up to 30°. Overall, our simulations offer insights into the fundamental properties of low-dimensional heterostructures and pave the way for their future application in energy-efficient electronic nanodevices.
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Affiliation(s)
| | - Richa Mitra
- Department
of Microtechnology and Nanoscience, Chalmers
University of Technology, SE-412 96Gothenburg, Sweden
| | - Naveen Shetty
- Department
of Microtechnology and Nanoscience, Chalmers
University of Technology, SE-412 96Gothenburg, Sweden
| | - Samuel Lara-Avila
- Department
of Microtechnology and Nanoscience, Chalmers
University of Technology, SE-412 96Gothenburg, Sweden
| | - Saroj Dash
- Department
of Microtechnology and Nanoscience, Chalmers
University of Technology, SE-412 96Gothenburg, Sweden
| | - Sergey Kubatkin
- Department
of Microtechnology and Nanoscience, Chalmers
University of Technology, SE-412 96Gothenburg, Sweden
| | - Julia Wiktor
- Department
of Physics, Chalmers University of Technology, SE-412 96Gothenburg, Sweden
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5
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Recent Progress on Graphene Flexible Photodetectors. MATERIALS 2022; 15:ma15144820. [PMID: 35888288 PMCID: PMC9318373 DOI: 10.3390/ma15144820] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Revised: 06/18/2022] [Accepted: 06/29/2022] [Indexed: 01/02/2023]
Abstract
In recent years, optoelectronics and related industries have developed rapidly. As typical optoelectronics devices, photodetectors (PDs) are widely applied in various fields. The functional materials in traditional PDs exhibit high hardness, and the performance of these rigid detectors is thus greatly reduced upon their stretching or bending. Therefore, the development of new flexible PDs with bendable and foldable functions is of great significance and has much interest in wearable, implantable optoelectronic devices. Graphene with excellent electrical and optical performance constructed on various flexible and rigid substrates has great potential in PDs. In this review, recent research progress on graphene-based flexible PDs is outlined. The research states of graphene conductive films are summarized, focusing on PDs based on single-component graphene and mixed-structure graphene, with a systematic analysis of their optical and mechanical performance, and the techniques for optimizing the PDs are also discussed. Finally, a summary of the current applications of graphene flexible PDs and perspectives is provided, and the remaining challenges are discussed.
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6
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Bafekry A, Karbasizadeh S, Faraji M, Bagheri Khatibani A, Sarsari IA, Gogova D, Ghergherehchi M. Van der Waals heterostructure of graphene and germanane: tuning the ohmic contact by electrostatic gating and mechanical strain. Phys Chem Chem Phys 2021; 23:21196-21206. [PMID: 34532725 DOI: 10.1039/d1cp03632g] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Recent exciting developments in synthesis and properties study of the Germanane (GeH) monolayer have inspired us to investigate the structural and electronic properties of the van der Waals GeH/Graphene (Gr) heterostructure by the first-principle approach. The stability of the GeH/Gr heterostructure is verified by calculating the phonon dispersion curves as well as by thermodynamic binding energy calculations. According to the band structure calculation, the GeH/Gr interface is n-type Ohmic. The effects of different interlayer distances and strains between the layers and the applied electric field on the interface have been investigated to gain insight into the van der Waals heterostructure modifications. An interlayer distance of 2.11 Å and compressive strain of 6% alter the contact from Ohmic to Schottky status, while the electric field can tune the GeH/Gr contact as p- or n-type, Ohmic, or Schottky. The average electrostatic potential of GeH/Gr and the Bader charge analysis have been used to explain the results obtained. Our theoretical study could provide a promising approach for improving the electronic performance of GeH/Gr-based nano-rectifiers.
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Affiliation(s)
- A Bafekry
- Department of Radiation Application, Shahid Beheshti University, 19839 69411 Tehran, Iran.
| | - S Karbasizadeh
- Department of Physics, Isfahan University of Technology, Isfahan, 84156-83111, Iran
| | - M Faraji
- TOBB University of Economics and Technology, Sogutozu Caddesi No 43 Sogutozu, 06560, Ankara, Turkey
| | - A Bagheri Khatibani
- Nano Research Lab, Lahijan Branch, Islamic Azad University, 1616, Lahijan, Iran
| | | | - D Gogova
- Department of Electrical and Computer Engineering, Sungkyunkwan University, 16419 Suwon, Korea
| | - M Ghergherehchi
- Department of Physics, Chemistry and Biology, Linkoping University, 58183, Linköping, Sweden.
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7
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Li S, Wang Y, Cheng P, Feng B, Chen L, Wu K. Realization of Large Scale, 2D van der Waals Heterojunction of SnS 2 /SnS by Reversible Sulfurization. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2101154. [PMID: 34331375 DOI: 10.1002/smll.202101154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 05/25/2021] [Indexed: 06/13/2023]
Abstract
2D van der Waals heterojunction provides an attractive opportunity for realizing novel electronic or optoelectronic devices. It remains challenging to realize high-quality heterostructures through scalable methods such as molecular epitaxy growth (MBE). Here, growth of few-layer SnS thin films is reported on mica and Nb-doped SrTiO3 (100) substrates by MBE. Then the top layer of SnS film is uniformly sulfurized to monolayer SnS2 in a sulfur atmosphere, resulting in a high-quality SnS2 /SnS 2D heterojunction. Furthermore, the SnS2 layer can be recovered to SnS by annealing SnS2 /SnS without sulfur supply, indicating the heterojunction formation is reversible. The scanning tunneling spectroscopy measurements on SnS2 /SnS heterostructure indicate the type-II band alignment in SnS2 /SnS. The work provides a promising approach to construct artificial 2D heterojunctions with desired properties, which could be extended to other sulfide and selenide systems.
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Affiliation(s)
- Shuhui Li
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Yu Wang
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Peng Cheng
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Baojie Feng
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Lan Chen
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Kehui Wu
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
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8
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Jung J, Odobesko A, Boshuis R, Szczerbakow A, Story T, Bode M. Systematic Investigation of the Coupling between One-Dimensional Edge States of a Topological Crystalline Insulator. PHYSICAL REVIEW LETTERS 2021; 126:236402. [PMID: 34170152 DOI: 10.1103/physrevlett.126.236402] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 05/18/2021] [Indexed: 06/13/2023]
Abstract
The interaction of spin-polarized one-dimensional (1D) topological edge modes localized along single-atomic steps of the topological crystalline insulator Pb_{0.7}Sn_{0.3}Se(001) has been studied systematically by scanning tunneling spectroscopy. Our results reveal that the coupling of adjacent edge modes sets in at a step-to-step distance d_{ss}≤25 nm, resulting in a characteristic splitting of a single peak at the Dirac point in tunneling spectra. Whereas the energy splitting exponentially increases with decreasing d_{ss} for single-atomic steps running almost parallel, we find no splitting for single-atomic step edges under an angle of 90°. The results are discussed in terms of overlapping wave functions with p_{x}, p_{y} orbital character.
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Affiliation(s)
- Johannes Jung
- Physikalisches Institut, Experimentelle Physik II, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Artem Odobesko
- Physikalisches Institut, Experimentelle Physik II, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Robin Boshuis
- Physikalisches Institut, Experimentelle Physik II, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Andrzej Szczerbakow
- Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02-668 Warsaw, Poland
| | - Tomasz Story
- Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02-668 Warsaw, Poland
- International Research Centre MagTop, Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, 02-668 Warsaw, Poland
| | - Matthias Bode
- Physikalisches Institut, Experimentelle Physik II, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
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9
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Silva A, Claerbout VEP, Polcar T, Kramer D, Nicolini P. Exploring the Stability of Twisted van der Waals Heterostructures. ACS APPLIED MATERIALS & INTERFACES 2020; 12:45214-45221. [PMID: 32894936 DOI: 10.1021/acsami.0c13971] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Recent research showed that the rotational degree of freedom in stacking 2D materials yields great changes in the electronic properties. Here, we focus on an often overlooked question: are twisted geometries stable and what defines their rotational energy landscape? Our simulations show how epitaxy theory breaks down in these systems, and we explain the observed behavior in terms of an interplay between flexural phonons and the interlayer coupling, governed by the moiré superlattice. Our argument, applied to the well-studied MoS2/graphene system, rationalizes experimental results and could serve as guidance to design twistronic devices.
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Affiliation(s)
- Andrea Silva
- Engineering Materials, University of Southampton, Southampton SO17 1BJ, U.K
- national Centre for Advanced Tribology Study at University of Southampton, Southampton SO17 1BJ, U.K
| | - Victor E P Claerbout
- Department of Control Engineering, Faculty of Electrical Engineering, Czech Technical University in Prague, Technicka 2, Prague 6 16627, Czech Republic
| | - Tomas Polcar
- Engineering Materials, University of Southampton, Southampton SO17 1BJ, U.K
- Department of Control Engineering, Faculty of Electrical Engineering, Czech Technical University in Prague, Technicka 2, Prague 6 16627, Czech Republic
| | - Denis Kramer
- Engineering Materials, University of Southampton, Southampton SO17 1BJ, U.K
- Mechanical Engineering, Helmut Schmidt University, Hamburg 22043, Germany
| | - Paolo Nicolini
- Department of Control Engineering, Faculty of Electrical Engineering, Czech Technical University in Prague, Technicka 2, Prague 6 16627, Czech Republic
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10
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Dai TJ, Chen YQ, Zhou ZY, Sun J, Peng XS, Liu XZ. Two-dimensional MoSe2/graphene heterostructure thin film with wafer-scale continuity via van der Waals epitaxy. Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2020.137762] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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11
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Li C, Han X, Zi Y, Hao D, Wu J, Wang F, Niu CY, Cho JH, Jia Y. Realization of asymmetric spin splitting Dirac cones in antiferromagnetic graphene/CrAs 2/graphene heterotrilayer. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:435503. [PMID: 32677626 DOI: 10.1088/1361-648x/aba6e5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 07/16/2020] [Indexed: 06/11/2023]
Abstract
Nonmagnetic graphene-based van der Waals heterotrilayers exhibit peculiar electronic features such as energetically and/or spatially resolved Dirac rings/cones. Here, using first-principles calculations we study the effect of magnetic proximity effect and mirror symmetry of antiferromagnetic CrAs2monolayer sandwiched between graphene on the Dirac cones. We clearly identify the common vertical shift of the Dirac bands in the spin up channel. While in the spin down channel, we surprisingly observe the remarkable transverse splitting Dirac cones. The underling mechanism can be attributed to the static electric field caused by the charge transfer between the interlayers, and the polarized field arising from the weakly magnetized graphene. Both fields collectively give rise to an inequivalent space inversion broken between graphene and CrAs2layers. Such unique Dirac states are absent in its nonmagnetic or ferromagnetic counterpart, ferromagnetic heterotrilayer with the glide symmetry, and graphene/CrAs2heterobilayer. Our findings would provide a new insight into the correlation between Dirac cones and magnetic monolayer sandwiched between graphene.
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Affiliation(s)
- Chong Li
- School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, People's Republic of China
| | - Xiaoyu Han
- Department of Chemistry, University of Manchester, Manchester M13 9PL, United Kingdom
- Department of Chemistry, University College London, London WC1H 0AJ, United Kingdom
| | - Yanbo Zi
- School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, People's Republic of China
| | - Dongfeng Hao
- School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, People's Republic of China
| | - Junhui Wu
- School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, People's Republic of China
| | - Fei Wang
- School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, People's Republic of China
| | - Chun-Yao Niu
- School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, People's Republic of China
| | - Jun-Hyung Cho
- School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, People's Republic of China
- Department of Physics and Research Institute for National Sciences, Hanyang University, 17 Haengdang-Dong, Seongdong-Ku, Seoul 133-791, Korea
| | - Yu Jia
- School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, People's Republic of China
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12
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Choi BK, Ulstrup S, Gunasekera SM, Kim J, Lim SY, Moreschini L, Oh JS, Chun SH, Jozwiak C, Bostwick A, Rotenberg E, Cheong H, Lyo IW, Mucha-Kruczynski M, Chang YJ. Visualizing Orbital Content of Electronic Bands in Anisotropic 2D Semiconducting ReSe 2. ACS NANO 2020; 14:7880-7891. [PMID: 32463224 DOI: 10.1021/acsnano.0c01054] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Many properties of layered materials change as they are thinned from their bulk forms down to single layers, with examples including indirect-to-direct band gap transition in 2H semiconducting transition metal dichalcogenides as well as thickness-dependent changes in the valence band structure in post-transition-metal monochalcogenides and black phosphorus. Here, we use angle-resolved photoemission spectroscopy to study the electronic band structure of monolayer ReSe2, a semiconductor with a distorted 1T structure and in-plane anisotropy. By changing the polarization of incoming photons, we demonstrate that for ReSe2, in contrast to the 2H materials, the out-of-plane transition metal dz2 and chalcogen pz orbitals do not contribute significantly to the top of the valence band, which explains the reported weak changes in the electronic structure of this compound as a function of layer number. We estimate a band gap of 1.7 eV in pristine ReSe2 using scanning tunneling spectroscopy and explore the implications on the gap following surface doping with potassium. A lower bound of 1.4 eV is estimated for the gap in the fully doped case, suggesting that doping-dependent many-body effects significantly affect the electronic properties of ReSe2. Our results, supported by density functional theory calculations, provide insight into the mechanisms behind polarization-dependent optical properties of rhenium dichalcogenides and highlight their place among two-dimensional crystals.
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Affiliation(s)
- Byoung Ki Choi
- Department of Physics, University of Seoul, Seoul 02504, Republic of Korea
| | - Søren Ulstrup
- Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
- Advanced Light Source (ALS), E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Surani M Gunasekera
- Centre for Nanoscience and Nanotechnology and Department of Physics, University of Bath, Bath BA2 7AY, United Kingdom
| | - Jiho Kim
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
| | - Soo Yeon Lim
- Department of Physics, Sogang University, Seoul 04107, Republic of Korea
| | - Luca Moreschini
- Advanced Light Source (ALS), E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Ji Seop Oh
- Advanced Light Source (ALS), E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - Seung-Hyun Chun
- Department of Physics, Sejong University, Seoul 05006, Republic of Korea
| | - Chris Jozwiak
- Advanced Light Source (ALS), E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Aaron Bostwick
- Advanced Light Source (ALS), E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Eli Rotenberg
- Advanced Light Source (ALS), E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Hyeonsik Cheong
- Department of Physics, Sogang University, Seoul 04107, Republic of Korea
| | - In-Whan Lyo
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
| | - Marcin Mucha-Kruczynski
- Centre for Nanoscience and Nanotechnology and Department of Physics, University of Bath, Bath BA2 7AY, United Kingdom
| | - Young Jun Chang
- Department of Physics, University of Seoul, Seoul 02504, Republic of Korea
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13
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Wan G, Panditharatne S, Fox NA, Cattelan M. Graphene-diamond junction photoemission microscopy and electronic interactions. NANO EXPRESS 2020. [DOI: 10.1088/2632-959x/aba443] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Abstract
Polycrystalline graphene was transferred onto differently terminated epitaxial layers of boron-doped diamond deposited onto single crystal substrates. Chemical and electronic characterisation was performed using energy-filtered photoemission electron microscopy and angle-resolved photoemission spectroscopy. Electronic interaction between the diamond and graphene was observed, where doping of the graphene on the hydrogen and oxygen terminated diamond was n-doping of 250 meV and 0 meV respectively. We found that the wide window of achievable graphene doping is effectively determined by the diamond surface dipole, easily tuneable with a varying surface functionalisation. A Schottky junction using the graphene-diamond structure was clearly observed and shown to reduce downward band bending of the hydrogen terminated diamond, producing a Schottky barrier height of 330 meV.
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14
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Yun FF, Cortie DL, Wang XL. Interactions in stanene centred van der Waals trilayers structures of boron-nitride and graphene: effect of mirror symmetry on electronic interactions. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:265001. [PMID: 32143209 DOI: 10.1088/1361-648x/ab7d62] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Dispersion-corrected density functional theory was used to investigate structures consisting of a stanene layer sandwiched between atomically-thin boron nitride and graphene. The parameters controlling the mirror symmetry, lattice rotation and stacking sequences were varied systematically to generate fifteen candidate trilayers. Two types of structural buckling occur in the heterostructures depending on whether the lattice vectors are co-aligned or non-collinear. The configurations with the honeycomb lattices rotated by π/6 with respect to the stanene generally have lower binding energy. In the majority of the trilayers, the electronic structures deviate strongly from the band structures of the isolated components. The boron nitride/stanene/boron nitride structure is identified as a special case where stanene has an electronic structure that is not perturbed by interlayer interactions and resembles the ideal monolayer form. For the other candidate structures, however, interlayer interactions drive significant modifications in the electronic structure thus indicating emergent features that go beyond the pure van der Waals description.
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Affiliation(s)
- Frank F Yun
- Spintronic and Electronic Materials Group, Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, North Wollongong, New South Wales 2500, Australia. Australian Research Council Centre of Excellence in Future Low Energy Electronics Technologies, University of Wollongong, North Wollongong, New South Wales 2500, Australia
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15
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Shen NF, Yang XD, Wang XX, Wang GH, Wan JG. Two-dimensional van der Waals heterostructure of indium selenide/hexagonal boron nitride with strong interlayer coupling. Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2020.137430] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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16
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de Andrade Deus DP, de Oliveira ISS. Tuning the Schottky barrier height in graphene/monolayer-GeI 2van der Waals heterostructure. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:355501. [PMID: 32320968 DOI: 10.1088/1361-648x/ab8bf8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 04/22/2020] [Indexed: 06/11/2023]
Abstract
We use first-principles simulations to investigate the structural and electronic properties of a heterostructure formed by graphene and monolayer GeI2(m-GeI2). While graphene has been extensively studied in the last 15 years, m-GeI2has been recently proposed to be a stable 2D semiconductor with a wide-band gap, Liuet al(2018J. Phys. Chem.C12222137). By staking both structures we obtain a metal-semiconductor junction, with great potential for applications in the designing of new (opto)electronic devices. The results show that the graphene Dirac cone is preserved in the graphene/m-GeI2heterostructure. We find that there are no chemical bonds at the graphene and m-GeI2interface, thus the heterostructure interactions are ruled by van der Waals (vdW) forces. The interface between graphene and m-GeI2results in a n-type Schottky contact. Furthermore, we show that a transition from n-type to p-type Schottky contact can be obtained by decreasing the interlayer distance. We also modulated the Schottky barrier heights by applying a perpendicular external electric field through the vdW heterostructure. In particular, positive values resulted in an increase of the n-type Schottky barrier height, while negative electric field values induced a transition from n-type to p-type Schottky contact. From our results, we show that m-GeI2is an interesting material to design new electronic Schottky devices based on graphene vdW heterostructures.
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Affiliation(s)
- D P de Andrade Deus
- Instituto Federal de Educação, Ciência e Tecnologia de Goiás, Departamento de Áreas Acadêmicas, Campus Jataí, 775 Orminda Vieira de Freitas, Jataí, GO, Brazil
| | - I S S de Oliveira
- Departamento de Física, Universidade Federal de Lavras, C.P. 3037, 37200-000, Lavras, MG, Brazil
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17
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Brem S, Lin KQ, Gillen R, Bauer JM, Maultzsch J, Lupton JM, Malic E. Hybridized intervalley moiré excitons and flat bands in twisted WSe 2 bilayers. NANOSCALE 2020; 12:11088-11094. [PMID: 32400821 DOI: 10.1039/d0nr02160a] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The large surface-to-volume ratio in atomically thin 2D materials allows to efficiently tune their properties through modifications of their environment. Artificial stacking of two monolayers into a bilayer leads to an overlap of layer-localized wave functions giving rise to a twist angle-dependent hybridization of excitonic states. In this joint theory-experiment study, we demonstrate the impact of interlayer hybridization on bright and momentum-dark excitons in twisted WSe2 bilayers. In particular, we show that the strong hybridization of electrons at the Λ point leads to a drastic redshift of the momentum-dark K-Λ exciton, accompanied by the emergence of flat moiré exciton bands at small twist angles. We directly compare theoretically predicted and experimentally measured optical spectra allowing us to identify photoluminescence signals stemming from phonon-assisted recombination of layer-hybridized dark excitons. Moreover, we predict the emergence of additional spectral features resulting from the moiré potential of the twisted bilayer lattice.
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Affiliation(s)
- Samuel Brem
- Chalmers University of Technology, Department of Physics, Gothenburg, Sweden.
| | - Kai-Qiang Lin
- University of Regensburg, Institute of Experimental and Applied Physics, Regensburg, Germany.
| | - Roland Gillen
- Friedrich-Alexander University Erlangen-Nuernberg, Institute of Condensed Matter Physics, Germany
| | - Jonas M Bauer
- University of Regensburg, Institute of Experimental and Applied Physics, Regensburg, Germany.
| | - Janina Maultzsch
- Friedrich-Alexander University Erlangen-Nuernberg, Institute of Condensed Matter Physics, Germany
| | - John M Lupton
- University of Regensburg, Institute of Experimental and Applied Physics, Regensburg, Germany.
| | - Ermin Malic
- Chalmers University of Technology, Department of Physics, Gothenburg, Sweden.
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18
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Ahmed T, Bellare P, Debnath R, Roy A, Ravishankar N, Ghosh A. Thermal History-Dependent Current Relaxation in hBN/MoS 2 van der Waals Dimers. ACS NANO 2020; 14:5909-5916. [PMID: 32310636 DOI: 10.1021/acsnano.0c01079] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Combining atomically thin layers of van der Waals (vdW) materials in a chosen vertical sequence is an emerging route to create devices with desired functionalities. While this method aims to exploit the individual properties of partnering layers, strong interlayer coupling can significantly alter their electronic and optical properties. Here we explored the impact of the vdW epitaxy on electrical transport in atomically thin molybdenum disulfide (MoS2) when it forms a vdW dimer with crystalline films of hexagonal boron nitride (hBN). We observe a thermal history-dependent long-term (over ∼40 h) current relaxation in the overlap region of MoS2/hBN heterostructures, which is absent in bare MoS2 layers (or homoepitaxial MoS2/MoS2 dimers) on the same substrate. Concurrent relaxation in the low-frequency Raman modes in MoS2 in the heterostructure region suggests a slow structural relaxation between trigonal and octahedral polymorphs of MoS2 as a likely driving mechanism that also results in inhomogeneous charge distribution in the MoS2 layer. Our experiment yields an aspect of vdW heteroepitaxy that can be generic to electrical devices with atomically thin transition-metal dichalcogenides.
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Affiliation(s)
- Tanweer Ahmed
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Pavithra Bellare
- Materials Research Centre, Indian Institute of Science, Bangalore 560012, India
| | - Rahul Debnath
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Ahin Roy
- Materials Research Centre, Indian Institute of Science, Bangalore 560012, India
| | | | - Arindam Ghosh
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
- Centre for Nano Science and Engineering, Indian Institute of Science, Bangalore 560012, India
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19
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Vo DD, Idrees M, Pham VT, Vu TV, Nguyen ST, Phuc HV, Hieu NN, Binh NT, Amin B, Nguyen CV. Electronic structure and optical performance of PbI2/SnSe2 heterostructure. Chem Phys 2020. [DOI: 10.1016/j.chemphys.2020.110736] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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20
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Xie WJ, Li X, Zhang FJ. Mo-vacancy induced high performance for photocatalytic hydrogen production over MoS2 nanosheets cocatalyst. Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2020.137276] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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21
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Nguyen HTT, Vu TV, Pham VT, Hieu NN, Phuc HV, Hoi BD, Binh NTT, Idrees M, Amin B, Nguyen CV. Computational insights into structural, electronic and optical characteristics of GeC/C 2N van der Waals heterostructures: effects of strain engineering and electric field. RSC Adv 2020; 10:2967-2974. [PMID: 35496107 PMCID: PMC9048868 DOI: 10.1039/c9ra08749d] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 01/03/2020] [Indexed: 01/14/2023] Open
Abstract
Vertical heterostructures from two or more than two two-dimensional materials are recently considered as an effective tool for tuning the electronic properties of materials and for designing future high-performance nanodevices. Here, using first principles calculations, we propose a GeC/C2N van der Waals heterostructure and investigate its electronic and optical properties. We demonstrate that the intrinsic electronic properties of both GeC and C2N monolayers are quite preserved in GeC/C2N HTS owing to the weak forces. At the equilibrium configuration, GeC/C2N HTS forms the type-II band alignment with an indirect band gap of 0.42 eV, which can be considered to improve the effective separation of electrons and holes. Besides, GeC/C2N vdW-HTS exhibits strong absorption in both visible and near ultra-violet regions with an intensity of 105 cm−1. The electronic properties of GeC/C2N HTS can be tuned by applying an electric field and vertical strains. The semiconductor to metal transition can be achieved in GeC/C2N HTS in the case when the positive electric field of +0.3 V Å−1 or the tensile vertical strain of −0.9 Å is applied. These findings demonstrate that GeC/C2N HTS can be used to design future high-performance multifunctional devices. Vertical heterostructures from two or more than two two-dimensional materials are recently considered as an effective tool for tuning the electronic properties of materials and for designing future high-performance nanodevices.![]()
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Affiliation(s)
- Hong T T Nguyen
- Division of Computational Physics, Institute for Computational Science, Ton Duc Thang University Ho Chi Minh City Vietnam .,Faculty of Electrical & Electronics Engineering, Ton Duc Thang University Ho Chi Minh City Vietnam
| | - Tuan V Vu
- Division of Computational Physics, Institute for Computational Science, Ton Duc Thang University Ho Chi Minh City Vietnam .,Faculty of Electrical & Electronics Engineering, Ton Duc Thang University Ho Chi Minh City Vietnam
| | - Van Thinh Pham
- Center of Excellence for Green Energy and Environmental Nanomaterials, Nguyen Tat Thanh University Ho Chi Minh City Vietnam
| | - Nguyen N Hieu
- Institute of Research and Development, Duy Tan University Da Nang 550000 Vietnam
| | - Huynh V Phuc
- Division of Theoretical Physics, Dong Thap University Cao Lanh 870000 Vietnam
| | - Bui D Hoi
- Department of Physics, University of Education, Hue University Hue Vietnam
| | - Nguyen T T Binh
- Institute of Research and Development, Duy Tan University Da Nang 550000 Vietnam
| | - M Idrees
- Department of Physics, Hazara University Mansehra 21300 Pakistan
| | - B Amin
- Department of Physics, Abbottabad University of Science and Technology Abbottabad 22010 Pakistan
| | - Chuong V Nguyen
- Department of Materials Science and Engineering, Le Quy Don Technical University Ha Noi 100000 Vietnam
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22
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Sánchez-Ochoa F, Hidalgo F, Pruneda M, Noguez C. Unfolding method for periodic twisted systems with commensurate Moiré patterns. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:025501. [PMID: 31530768 DOI: 10.1088/1361-648x/ab44f0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We present a general unfolding method for the electronic bands of systems with double-periodicity. Within density functional theory with atomic orbitals as basis-set, our method takes into account two symmetry operations of the primitive cell: a standard expansion and a single rotation, letting to elucidate the physical effects associated to the mutual interactions between systems with more than one periodicity. As a result, our unfolding method allows studying the electronic properties of vertically stacked two-dimensional homo- or heterostructures. We apply our method to study [Formula: see text] single-layer graphene, [Formula: see text] twisted single-layer graphene, and [Formula: see text] graphene- [Formula: see text] tungsten disulfide heterostructure with an interlayer angle of [Formula: see text]. Our unfolding method allows observing typical mini gaps reported in heterostructures, as well as other electronic deviations from pristine structures, impossible to distinguish without an unfolding method. We anticipate that this unfolding method can be useful to compare with experiments to elucidate the electronic properties of two-dimensional homo- or heterostructures, where the interlayer angle can be considered as an additional parameter.
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Affiliation(s)
- F Sánchez-Ochoa
- Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20-364, Cd. de México C.P. 01000, Mexico
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23
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Sung D, Min KA, Hong S. Investigation of atomic and electronic properties of 2D-MoS 2/3D-GaN mixed-dimensional heterostructures. NANOTECHNOLOGY 2019; 30:404002. [PMID: 31234153 DOI: 10.1088/1361-6528/ab2c16] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We have performed density functional theory calculations to study the effects caused by the interfacial structure between 2D-MoS2 and 3D-GaN. Two different surface terminations of GaN are considered: Ga-terminated (0001) (Ga-GaN) and N-terminated ([Formula: see text]) (N-GaN) configurations. We confirm that Rashba spin splitting occurs in band structure of MoS2 on GaN. We also find that the surface states of GaN move to the deep position in band structure in the MoS2/Ga-GaN case, while the surface states of GaN are hybridized with MoS2 near the Fermi level for the MoS2/N-GaN case. Furthermore, we investigate the variation in electronic structure of MoS2/GaN heterostructures depending on the number of MoS2 layers. Especially, the top layer MoS2 of the 2L-MoS2/GaN structures shows both n-type and p-type properties depending on the GaN surface termination. As a result, we suggest that the electrical characteristics of the 2D/3D heterostructures could be controlled by the surface terminations of substrate materials.
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Affiliation(s)
- Dongchul Sung
- Graphene Research Institute, Department of Physics and Astronomy, Sejong University, Seoul 05006, Republic of Korea
| | - Kyung-Ah Min
- Graphene Research Institute, Department of Physics and Astronomy, Sejong University, Seoul 05006, Republic of Korea
| | - Suklyun Hong
- Graphene Research Institute, Department of Physics and Astronomy, Sejong University, Seoul 05006, Republic of Korea
- Graphene Research Institute-Texas Photonics Center International Research Center (GRI-TPC IRC), Sejong University, Seoul 05006, Republic of Korea
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24
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Lee K, Li J, Cheng L, Wang J, Kumar D, Wang Q, Chen M, Wu Y, Eda G, Chia EEM, Chang H, Yang H. Sub-Picosecond Carrier Dynamics Induced by Efficient Charge Transfer in MoTe 2/WTe 2 van der Waals Heterostructures. ACS NANO 2019; 13:9587-9594. [PMID: 31322858 DOI: 10.1021/acsnano.9b04701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Demonstration of van der Waals (vdW) semiconductor/metal heterostructures (SMHs) based on transition metal dichalcogenides has been a central approach in high-speed electronics by introducing ultrafast carrier dynamics. In this regard, a Weyl semimetal WTe2 is of great interest due to its vdW layered nature, low work function, and superior electrical properties. However, little is still known about its heterostructures, and a few picoseconds photocarrier lifetimes hinder its applications in high-speed electronics. Here, we propose a SMH: semimetallic Td phase WTe2 with its sister compound of semiconducting 2H phase MoTe2. Time-resolved terahertz (THz) spectroscopy demonstrated that WTe2 exhibited the significantly shorter carrier lifetimes of sub-picosecond when forming a junction with MoTe2. We provided explicit characteristic signatures, revealing charge transfer across the interface and the subsequent interlayer exciton decay. This work not only offers the extension of the THz detection scope of ultrafast phenomena from atomically thin materials but also provides a building block of vertical SMHs for high-speed electronic devices with sub-picosecond photocarrier lifetimes.
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Affiliation(s)
- Kyusup Lee
- Department of Electrical and Computer Engineering and NUSNNI , National University of Singapore , 117576 Singapore
| | - Jie Li
- Center for Joining and Electronic Packaging, State Key Laboratory of Material Processing and Die & Mould Technology, School of Materials Science and Engineering , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Liang Cheng
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences , Nanyang Technological University , 637371 Singapore
| | - Junyong Wang
- Department of Physics , National University of Singapore , 119077 Singapore
| | - Dushyant Kumar
- Department of Electrical and Computer Engineering and NUSNNI , National University of Singapore , 117576 Singapore
| | - Qisheng Wang
- Department of Electrical and Computer Engineering and NUSNNI , National University of Singapore , 117576 Singapore
| | - Mengji Chen
- Department of Electrical and Computer Engineering and NUSNNI , National University of Singapore , 117576 Singapore
| | - Yang Wu
- Department of Electrical and Computer Engineering and NUSNNI , National University of Singapore , 117576 Singapore
| | - Goki Eda
- Department of Physics , National University of Singapore , 119077 Singapore
| | - Elbert E M Chia
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences , Nanyang Technological University , 637371 Singapore
| | - Haixin Chang
- Center for Joining and Electronic Packaging, State Key Laboratory of Material Processing and Die & Mould Technology, School of Materials Science and Engineering , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Hyunsoo Yang
- Department of Electrical and Computer Engineering and NUSNNI , National University of Singapore , 117576 Singapore
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25
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Mashhadi S, Kim Y, Kim J, Weber D, Taniguchi T, Watanabe K, Park N, Lotsch B, Smet JH, Burghard M, Kern K. Spin-Split Band Hybridization in Graphene Proximitized with α-RuCl 3 Nanosheets. NANO LETTERS 2019; 19:4659-4665. [PMID: 31241971 DOI: 10.1021/acs.nanolett.9b01691] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Proximity effects induced in the two-dimensional Dirac material graphene potentially open access to novel and intriguing physical phenomena. Thus far, the coupling between graphene and ferromagnetic insulators has been experimentally established. However, only very little is known about graphene's interaction with antiferromagnetic insulators. Here, we report a low-temperature study of the electronic properties of high quality van der Waals heterostructures composed of a single graphene layer proximitized with α-RuCl3. The latter is known to become antiferromagnetically ordered below 10 K. Shubnikov-de Haas oscillations in the longitudinal resistance together with Hall resistance measurements provide clear evidence for a band realignment that is accompanied by a transfer of electrons originally occupying the graphene's spin degenerate Dirac cones into α-RuCl3 band states with in-plane spin polarization. Left behind are holes in two separate Fermi pockets, only the dispersion of one of which is distorted near the Fermi energy due to spin selective hybridization with these spin polarized α-RuCl3 band states. This interpretation is supported by our density functional theory calculations. An unexpected damping of the quantum oscillations as well as a zero-field resistance upturn close to the Néel temperature of α-RuCl3 suggest the onset of additional spin scattering due to spin fluctuations in the α-RuCl3.
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Affiliation(s)
- Soudabeh Mashhadi
- Max-Planck-Institut für Festkörperforschung , Heisenbergstrasse 1 , D-70569 Stuttgart , Germany
| | - Youngwook Kim
- Max-Planck-Institut für Festkörperforschung , Heisenbergstrasse 1 , D-70569 Stuttgart , Germany
- Department of Emerging Materials Science , DGIST , 333 Techno-Jungang-daero, Hyeonpung-Myun, Dalseong-Gun, Daegu 42988 Korea
| | - Jeongwoo Kim
- Department of Physics , Incheon National University , Incheon 22012 , Republic of Korea
- Department of Physics , Ulsan National Institute of Science and Technology, UNIST-gil 50 , Ulsan 44919 , Republic of Korea
| | - Daniel Weber
- Department of Chemistry and Biochemistry , The Ohio State University , Columbus , Ohio 43210 , United States
| | - Takashi Taniguchi
- National Institute for Materials Science , 1-1 Namiki, Tsukuba , 305-0044 , Japan
| | - Kenji Watanabe
- National Institute for Materials Science , 1-1 Namiki, Tsukuba , 305-0044 , Japan
| | - Noejung Park
- Department of Physics , Ulsan National Institute of Science and Technology, UNIST-gil 50 , Ulsan 44919 , Republic of Korea
| | - Bettina Lotsch
- Max-Planck-Institut für Festkörperforschung , Heisenbergstrasse 1 , D-70569 Stuttgart , Germany
| | - Jurgen H Smet
- Max-Planck-Institut für Festkörperforschung , Heisenbergstrasse 1 , D-70569 Stuttgart , Germany
| | - Marko Burghard
- Max-Planck-Institut für Festkörperforschung , Heisenbergstrasse 1 , D-70569 Stuttgart , Germany
| | - Klaus Kern
- Max-Planck-Institut für Festkörperforschung , Heisenbergstrasse 1 , D-70569 Stuttgart , Germany
- Institut de Physique , Ecole Polytechnique Fédérale de Lausanne , CH-1015 Lausanne , Switzerland
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26
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Jin S, Wang X, Han P, Sun W, Feng S, Ye J, Zhang C, Zhang Y. Modulation of terahertz radiation from graphene surface plasmon polaritons via surface acoustic wave. OPTICS EXPRESS 2019; 27:11137-11151. [PMID: 31052962 DOI: 10.1364/oe.27.011137] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 03/17/2019] [Indexed: 06/09/2023]
Abstract
We present a theoretical study of terahertz (THz) radiation induced by surface plasmon polaritons (SPPs) on a graphene layer under modulation by a surface acoustic wave (SAW). In our gedanken experiment, SPPs are excited by an electron beam moving on a graphene layer situated on a piezoelectric MoS2 flake. Under modulation by the SAW field, charge carriers are periodically distributed over the MoS2 flake, and this causes periodically distributed permittivity. The periodic permittivity structure of the MoS2 flake folds the SPP dispersion curve back into the center of the first Brillouin zone, in a manner analogous to a crystal, leading to THz radiation emission with conservation of the wavevectors between the SPPs and the electromagnetic waves. Both the frequency and the intensity of the THz radiation are tuned by adjusting the chemical potential of the graphene layer, the MoS2 flake doping density, and the wavelength and period of the external SAW field. A maximum energy conversion efficiency as high as ninety percent was obtained from our model calculations. These results indicate an opportunity to develop highly tunable and integratable THz sources based on graphene devices.
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27
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Cucchi I, Gutiérrez-Lezama I, Cappelli E, McKeown Walker S, Bruno FY, Tenasini G, Wang L, Ubrig N, Barreteau C, Giannini E, Gibertini M, Tamai A, Morpurgo AF, Baumberger F. Microfocus Laser-Angle-Resolved Photoemission on Encapsulated Mono-, Bi-, and Few-Layer 1T'-WTe 2. NANO LETTERS 2019; 19:554-560. [PMID: 30570259 DOI: 10.1021/acs.nanolett.8b04534] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Two-dimensional crystals of semi-metallic van der Waals materials hold much potential for the realization of novel phases, as exemplified by the recent discoveries of a polar metal in few-layer 1T'-WTe2 and of a quantum spin Hall state in monolayers of the same material. Understanding these phases is particularly challenging because little is known from experiments about the momentum space electronic structure of ultrathin crystals. Here, we report direct electronic structure measurements of exfoliated mono-, bi-, and few-layer 1T'-WTe2 by laser-based microfocus angle-resolved photoemission. This is achieved by encapsulating with monolayer graphene a flake of WTe2 comprising regions of different thickness. Our data support the recent identification of a quantum spin Hall state in monolayer 1T'-WTe2 and reveal strong signatures of the broken inversion symmetry in the bilayer. We finally discuss the sensitivity of encapsulated samples to contaminants following exposure to ambient atmosphere.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Marco Gibertini
- National Centre for Computational Design and Discovery of Novel Materials (MARVEL) , École Polytechnique Fedérale de Lausanne , CH-1015 Lausanne , Switzerland
| | | | | | - Felix Baumberger
- Swiss Light Source , Paul Scherrer Institute , CH-5232 Villigen , Switzerland
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28
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Shu H, Wang Y, Sun M. Enhancing electronic and optical properties of monolayer MoSe2via a MoSe2/blue phosphorene heterobilayer. Phys Chem Chem Phys 2019; 21:15760-15766. [DOI: 10.1039/c9cp02743b] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Type-II heterostructures are appealing for application in optoelectronics due to their effective separation of photogenerated charge carriers.
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Affiliation(s)
- Huabing Shu
- School of Science
- Jiangsu University of Science and Technology
- Zhenjiang 212001
- China
| | - Ying Wang
- School of Science
- Jiangsu University of Science and Technology
- Zhenjiang 212001
- China
| | - Minglei Sun
- School of Mechanical Engineering
- Southeast University
- Nanjing 211189
- China
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Deng Z, Wang X. Strain engineering on the electronic states of two-dimensional GaN/graphene heterostructure. RSC Adv 2019; 9:26024-26029. [PMID: 35531004 PMCID: PMC9070312 DOI: 10.1039/c9ra03175h] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 08/05/2019] [Indexed: 11/21/2022] Open
Abstract
Combining two different layered structures to form a van der Waals (vdW) heterostructure has recently emerged as an intriguing way of designing electronic and optoelectronic devices. Effects of the strain on the electronic properties of GaN/graphene heterostructure are investigated by using first-principles calculation. In the GaN/graphene heterostructure, the strain can control not only the Schottky barrier, but also contact types at the interface. Moreover, when the uniaxial strain is above −1% or the biaxial strain is above 0%, the contact type transforms to ohmic contact. These results provide a detailed understanding of the interfacial properties of GaN/graphene and help to predict the performance of the GaN/graphene heterostructure on nanoelectronics and nanocomposites. Combining two different layered structures to form a van der Waals (vdW) heterostructure has recently emerged as an intriguing way of designing electronic and optoelectronic devices.![]()
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Affiliation(s)
- Zhongxun Deng
- Shanxi Province Key Laboratory of Electrical Materials and Infiltration Technology
- School of Materials Science and Engineering
- Xi'an University of Technology
- Xi'an 710048
- P. R. China
| | - Xianhui Wang
- Shanxi Province Key Laboratory of Electrical Materials and Infiltration Technology
- School of Materials Science and Engineering
- Xi'an University of Technology
- Xi'an 710048
- P. R. China
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30
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Wang J, Li L, Shen Z, Guo P, Li M, Zhao B, Fang L, Yang L. Ultralow Interlayer Friction of Layered Electride Ca₂N: A Potential Two-Dimensional Solid Lubricant Material. MATERIALS 2018; 11:ma11122462. [PMID: 30518136 PMCID: PMC6317045 DOI: 10.3390/ma11122462] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 11/28/2018] [Accepted: 12/03/2018] [Indexed: 11/28/2022]
Abstract
Dispersion-corrected density functional theory (DFT) calculations reveal that the layered electride of dicalcium nitride (Ca2N) exhibits stronger interlayer binding interactions but lower interlayer friction behavior than that of traditional layered lubricants weakly bonded by van der Waals (vdW) interactions, such as graphite, h-BN, and MoS2. These results are attributed to the two-dimensional (2D) homogeneous conduction electrons distribution in the middle of the interlayer space of Ca2N, which yields a smooth sliding barrier and hence ultralow friction behavior. The interesting results obtained in this study have not only broadened the scope of 2D solid lubricants but also enriched the physical understanding of ultralow friction mechanism for 2D systems.
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Affiliation(s)
- Jianjun Wang
- Computational and Design Center for Low-dimensional Quantum Material, and College of Science, Zhongyuan University of Technology, Zhengzhou 450007, China.
| | - Lin Li
- Delivery Devices and Connected Solutions, Eli Lilly and Company, Indianapolis, IN 46285, USA.
| | - Ziting Shen
- Computational and Design Center for Low-dimensional Quantum Material, and College of Science, Zhongyuan University of Technology, Zhengzhou 450007, China.
| | - Peng Guo
- Computational and Design Center for Low-dimensional Quantum Material, and College of Science, Zhongyuan University of Technology, Zhengzhou 450007, China.
| | - Meng Li
- Computational and Design Center for Low-dimensional Quantum Material, and College of Science, Zhongyuan University of Technology, Zhengzhou 450007, China.
| | - Bin Zhao
- Computational and Design Center for Low-dimensional Quantum Material, and College of Science, Zhongyuan University of Technology, Zhengzhou 450007, China.
| | - Lili Fang
- Computational and Design Center for Low-dimensional Quantum Material, and College of Science, Zhongyuan University of Technology, Zhengzhou 450007, China.
| | - Linfeng Yang
- Computational and Design Center for Low-dimensional Quantum Material, and College of Science, Zhongyuan University of Technology, Zhengzhou 450007, China.
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31
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Le PTT, Hieu NN, Bui LM, Phuc HV, Hoi BD, Amin B, Nguyen CV. Structural and electronic properties of a van der Waals heterostructure based on silicene and gallium selenide: effect of strain and electric field. Phys Chem Chem Phys 2018; 20:27856-27864. [PMID: 30398248 DOI: 10.1039/c8cp05588b] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Combining van der Waals heterostructures by stacking different two-dimensional materials on top of each other layer-by-layer can enhance their desired properties and greatly extend the applications of the parent materials. In this work, by means of first principles calculations, we investigate systematically the structural and electronic properties of six different stacking configurations of a Si/GaSe heterostructure. The effect of biaxial strain and electric field on the electronic properties of the most energetically stable configuration of the Si/GaSe heterostructure has also been discussed. At the equilibrium state, the electronic properties of the Si/GaSe heterostructure in all its stacking configurations are well kept as compared with that of single layers owing to their weak van der Waals interactions. Interestingly, we find that a sizable band gap is opened at the Dirac K point of silicene in the Si/GaSe heterostructure, which could be further controlled by biaxial strain or electric field. These findings open up a possibility for designing silicene-based electronic devices, which exhibit a controllable band gap. Furthermore, the Si/GaSe heterostructure forms an n-type Schottky contact with a small Schottky barrier height of 0.23 eV. A transformation from the n-type Schottky contact to a p-type one, or from the Schottky contact to an ohmic contact may occur in the Si/GaSe heterostructure when strain or an electric field is applied.
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Affiliation(s)
- P T T Le
- Theoretical Physics Research Group, Advanced Institute of Materials Science, Ton Duc Thang University, Ho Chi Minh City, Viet Nam.
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32
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Kim D, Jung JH, Ihm J. Theoretical Study of Aluminum Hydroxide as a Hydrogen-Bonded Layered Material. NANOMATERIALS 2018; 8:nano8060375. [PMID: 29843410 PMCID: PMC6027226 DOI: 10.3390/nano8060375] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 05/23/2018] [Accepted: 05/25/2018] [Indexed: 12/02/2022]
Abstract
In many layer-structured materials, constituent layers are bound through van der Waals (vdW) interactions. However, hydrogen bonding is another type of weak interaction which can contribute to the formation of multi-layered materials. In this work, we investigate aluminum hydroxide [Al(OH)3] having hydrogen bonding as an interlayer binding mechanism. We study the crystal structures and electronic band structures of bulk, single-layer, and multi-layer Al(OH)3 using density functional theory calculations. We find that hydrogen bonds across the constituent layers indeed give rise to interlayer binding stronger than vdW interactions, and a reduction of the band gap occurs for an isolated layer as compared to bulk Al(OH)3 which is attributed to the emergence of surface states. We also consider the alkali-halide intercalation between layers and examine how the intercalated atoms affect the atomic and electronic structures of Al(OH)3.
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Affiliation(s)
- Dongwook Kim
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea.
| | - Jong Hyun Jung
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea.
| | - Jisoon Ihm
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, Korea.
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33
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Cattelan M, Fox NA. A Perspective on the Application of Spatially Resolved ARPES for 2D Materials. NANOMATERIALS (BASEL, SWITZERLAND) 2018; 8:E284. [PMID: 29702567 PMCID: PMC5977298 DOI: 10.3390/nano8050284] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 04/20/2018] [Accepted: 04/23/2018] [Indexed: 12/13/2022]
Abstract
In this paper, a perspective on the application of Spatially- and Angle-Resolved PhotoEmission Spectroscopy (ARPES) for the study of two-dimensional (2D) materials is presented. ARPES allows the direct measurement of the electronic band structure of materials generating extremely useful insights into their electronic properties. The possibility to apply this technique to 2D materials is of paramount importance because these ultrathin layers are considered fundamental for future electronic, photonic and spintronic devices. In this review an overview of the technical aspects of spatially localized ARPES is given along with a description of the most advanced setups for laboratory and synchrotron-based equipment. This technique is sensitive to the lateral dimensions of the sample. Therefore, a discussion on the preparation methods of 2D material is presented. Some of the most interesting results obtained by ARPES are reported in three sections including: graphene, transition metal dichalcogenides (TMDCs) and 2D heterostructures. Graphene has played a key role in ARPES studies because it inspired the use of this technique with other 2D materials. TMDCs are presented for their peculiar transport, optical and spin properties. Finally, the section featuring heterostructures highlights a future direction for research into 2D material structures.
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Affiliation(s)
- Mattia Cattelan
- School of Chemistry, University of Bristol, Cantocks Close, Bristol BS8 1TS, UK; .
| | - Neil A Fox
- School of Chemistry, University of Bristol, Cantocks Close, Bristol BS8 1TS, UK; .
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK.
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34
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Dau MT, Gay M, Di Felice D, Vergnaud C, Marty A, Beigné C, Renaud G, Renault O, Mallet P, Le Quang T, Veuillen JY, Huder L, Renard VT, Chapelier C, Zamborlini G, Jugovac M, Feyer V, Dappe YJ, Pochet P, Jamet M. Beyond van der Waals Interaction: The Case of MoSe 2 Epitaxially Grown on Few-Layer Graphene. ACS NANO 2018; 12:2319-2331. [PMID: 29384649 DOI: 10.1021/acsnano.7b07446] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Van der Waals heterojunctions composed of graphene and transition metal dichalcogenides have gain much attention because of the possibility to control and tailor band structure, promising applications in two-dimensional optoelectronics and electronics. In this report, we characterized the van der Waals heterojunction MoSe2/few-layer graphene with a high-quality interface using cutting-edge surface techniques scaling from atomic to microscopic range. These surface analyses gave us a complete picture of the atomic structure and electronic properties of the heterojunction. In particular, we found two important results: the commensurability between the MoSe2 and few-layer graphene lattices and a band-gap opening in the few-layer graphene. The band gap is as large as 250 meV, and we ascribed it to an interface charge transfer that results in an electronic depletion in the few-layer graphene. This conclusion is well supported by electron spectroscopy data and density functional theory calculations. The commensurability between the MoSe2 and graphene lattices as well as the band-gap opening clearly show that the interlayer interaction goes beyond the simple van der Waals interaction. Hence, stacking two-dimensional materials in van der Waals heterojunctions enables us to tailor the atomic and electronic properties of individual layers. It also permits the introduction of a band gap in few-layer graphene by interface charge transfer.
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Affiliation(s)
- Minh Tuan Dau
- Université Grenoble Alpes , CEA, CNRS, Grenoble INP, INAC-SPINTEC, 38000 Grenoble , France
| | - Maxime Gay
- Université Grenoble Alpes , CEA, LETI, Minatec Campus, F-38054 Grenoble , France
| | - Daniela Di Felice
- SPEC, CEA, CNRS, Université Paris Saclay , CEA Saclay, 91191 Gif-sur-Yvette Cedex , France
| | - Céline Vergnaud
- Université Grenoble Alpes , CEA, CNRS, Grenoble INP, INAC-SPINTEC, 38000 Grenoble , France
| | - Alain Marty
- Université Grenoble Alpes , CEA, CNRS, Grenoble INP, INAC-SPINTEC, 38000 Grenoble , France
| | - Cyrille Beigné
- Université Grenoble Alpes , CEA, CNRS, Grenoble INP, INAC-SPINTEC, 38000 Grenoble , France
| | - Gilles Renaud
- Université Grenoble Alpes , CEA, INAC, MEM, 38000 Grenoble , France
| | - Olivier Renault
- Université Grenoble Alpes , CEA, LETI, Minatec Campus, F-38054 Grenoble , France
| | - Pierre Mallet
- Université Grenoble Alpes, CNRS, Institut Néel , F-38000 Grenoble , France
| | - Toai Le Quang
- Université Grenoble Alpes, CNRS, Institut Néel , F-38000 Grenoble , France
| | - Jean-Yves Veuillen
- Université Grenoble Alpes, CNRS, Institut Néel , F-38000 Grenoble , France
| | - Loïc Huder
- Université Grenoble Alpes , CEA, INAC, PHELIQS, 38000 Grenoble , France
| | - Vincent T Renard
- Université Grenoble Alpes , CEA, INAC, PHELIQS, 38000 Grenoble , France
| | - Claude Chapelier
- Université Grenoble Alpes , CEA, INAC, PHELIQS, 38000 Grenoble , France
| | - Giovanni Zamborlini
- Peter Grünberg Institute (PGI-6), Forschungszentrum Jülich GmbH , D-52425 , Jülich , Germany
| | - Matteo Jugovac
- Peter Grünberg Institute (PGI-6), Forschungszentrum Jülich GmbH , D-52425 , Jülich , Germany
| | - Vitaliy Feyer
- Peter Grünberg Institute (PGI-6), Forschungszentrum Jülich GmbH , D-52425 , Jülich , Germany
| | - Yannick J Dappe
- SPEC, CEA, CNRS, Université Paris Saclay , CEA Saclay, 91191 Gif-sur-Yvette Cedex , France
| | - Pascal Pochet
- Université Grenoble Alpes , CEA, INAC, MEM, 38000 Grenoble , France
| | - Matthieu Jamet
- Université Grenoble Alpes , CEA, CNRS, Grenoble INP, INAC-SPINTEC, 38000 Grenoble , France
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35
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Solís-Fernández P, Bissett M, Ago H. Synthesis, structure and applications of graphene-based 2D heterostructures. Chem Soc Rev 2018; 46:4572-4613. [PMID: 28691726 DOI: 10.1039/c7cs00160f] [Citation(s) in RCA: 100] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
With the profuse amount of two-dimensional (2D) materials discovered and the improvements in their synthesis and handling, the field of 2D heterostructures has gained increased interest in recent years. Such heterostructures not only overcome the inherent limitations of each of the materials, but also allow the realization of novel properties by their proper combination. The physical and mechanical properties of graphene mean it has a prominent place in the area of 2D heterostructures. In this review, we will discuss the evolution and current state in the synthesis and applications of graphene-based 2D heterostructures. In addition to stacked and in-plane heterostructures with other 2D materials and their potential applications, we will also cover heterostructures realized with lower dimensionality materials, along with intercalation in few-layer graphene as a special case of a heterostructure. Finally, graphene heterostructures produced using liquid phase exfoliation techniques and their applications to energy storage will be reviewed.
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36
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Chen C, Avila J, Wang S, Wang Y, Mucha-Kruczyński M, Shen C, Yang R, Nosarzewski B, Devereaux TP, Zhang G, Asensio MC. Emergence of Interfacial Polarons from Electron-Phonon Coupling in Graphene/h-BN van der Waals Heterostructures. NANO LETTERS 2018; 18:1082-1087. [PMID: 29302973 DOI: 10.1021/acs.nanolett.7b04604] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
van der Waals heterostructures, vertical stacks of layered materials, offer new opportunities for novel quantum phenomena which are absent in their constituent components. Here we report the emergence of polaron quasiparticles at the interface of graphene/hexagonal boron nitride (h-BN) heterostructures. Using nanospot angle-resolved photoemission spectroscopy, we observe zone-corner replicas of h-BN valence band maxima, with energy spacing coincident with the highest phonon energy of the heterostructure, an indication of Fröhlich polaron formation due to forward-scattering electron-phonon coupling. Parabolic fitting of the h-BN bands yields an effective mass enhancement of ∼2.3, suggesting an intermediate coupling strength. Our theoretical simulations based on Migdal-Eliashberg theory corroborate the experimental results, allowing the extraction of microscopic physical parameters. Moreover, renormalization of graphene π-band is observed due to the hybridization with the h-BN band. Our work generalizes the polaron study from transition metal oxides to van der Waals heterostructures with higher material flexibility, highlighting interlayer coupling as an extra degree of freedom to explore emergent phenomena.
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Affiliation(s)
- Chaoyu Chen
- ANTARES Beamline, Synchrotron SOLEIL and Université Paris-Saclay , L'Orme des Merisiers, Saint Aubin-BP 48, 91192 Gif sur Yvette Cedex, France
| | - José Avila
- ANTARES Beamline, Synchrotron SOLEIL and Université Paris-Saclay , L'Orme des Merisiers, Saint Aubin-BP 48, 91192 Gif sur Yvette Cedex, France
| | - Shuopei Wang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences , Beijing 100190, China
| | - Yao Wang
- Department of Applied Physics, Stanford University , California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Laboratory and Stanford University , Menlo Park, California 94025, United States
- Department of Physics, Harvard University , Cambridge, Massachussetts 02138, United States
| | - Marcin Mucha-Kruczyński
- Department of Physics, University of Bath , Claverton Down, Bath BA2 7AY, United Kingdom
- Centre for Nanoscience and Nanotechnology, University of Bath , Claverton Down, Bath BA2 7AY, United Kingdom
| | - Cheng Shen
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences , Beijing 100190, China
| | - Rong Yang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences , Beijing 100190, China
| | - Benjamin Nosarzewski
- Department of Applied Physics, Stanford University , California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Laboratory and Stanford University , Menlo Park, California 94025, United States
| | - Thomas P Devereaux
- Stanford Institute for Materials and Energy Sciences, SLAC National Laboratory and Stanford University , Menlo Park, California 94025, United States
- Geballe Laboratory for Advanced Materials, Stanford University , California 94305, United States
| | - Guangyu Zhang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences , Beijing 100190, China
| | - Maria Carmen Asensio
- ANTARES Beamline, Synchrotron SOLEIL and Université Paris-Saclay , L'Orme des Merisiers, Saint Aubin-BP 48, 91192 Gif sur Yvette Cedex, France
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37
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Yuan L, Chung TF, Kuc A, Wan Y, Xu Y, Chen YP, Heine T, Huang L. Photocarrier generation from interlayer charge-transfer transitions in WS 2-graphene heterostructures. SCIENCE ADVANCES 2018; 4:e1700324. [PMID: 29423439 PMCID: PMC5804583 DOI: 10.1126/sciadv.1700324] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 01/02/2018] [Indexed: 05/23/2023]
Abstract
Efficient interfacial carrier generation in van der Waals heterostructures is critical for their electronic and optoelectronic applications. We demonstrate broadband photocarrier generation in WS2-graphene heterostructures by imaging interlayer coupling-dependent charge generation using ultrafast transient absorption microscopy. Interlayer charge-transfer (CT) transitions and hot carrier injection from graphene allow carrier generation by excitation as low as 0.8 eV below the WS2 bandgap. The experimentally determined interlayer CT transition energies are consistent with those predicted from the first-principles band structure calculation. CT interactions also lead to additional carrier generation in the visible spectral range in the heterostructures compared to that in the single-layer WS2 alone. The lifetime of the charge-separated states is measured to be ~1 ps. These results suggest that interlayer interactions make graphene-two-dimensional semiconductor heterostructures very attractive for photovoltaic and photodetector applications because of the combined benefits of high carrier mobility and enhanced broadband photocarrier generation.
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Affiliation(s)
- Long Yuan
- Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Ting-Fung Chung
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA
- Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907, USA
| | - Agnieszka Kuc
- Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, 04103 Leipzig, Germany
- Department of Physics & Earth Science, Jacobs University Bremen, 28759 Bremen, Germany
| | - Yan Wan
- Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Yang Xu
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA
- Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907, USA
| | - Yong P Chen
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA
- Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907, USA
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Thomas Heine
- Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, 04103 Leipzig, Germany
- Department of Physics & Earth Science, Jacobs University Bremen, 28759 Bremen, Germany
| | - Libai Huang
- Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA
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38
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Phuc HV, Hieu NN, Hoi BD, Nguyen CV. Interlayer coupling and electric field tunable electronic properties and Schottky barrier in a graphene/bilayer-GaSe van der Waals heterostructure. Phys Chem Chem Phys 2018; 20:17899-17908. [DOI: 10.1039/c8cp02190b] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
In this work, using density functional theory we investigated systematically the electronic properties and Schottky barrier modulation in a multilayer graphene/bilayer-GaSe heterostructure by varying the interlayer spacing and by applying an external electric field.
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Affiliation(s)
- Huynh V. Phuc
- Institute of Research and Development
- Duy Tan University
- Da Nang
- Vietnam
| | - Nguyen N. Hieu
- Institute of Research and Development
- Duy Tan University
- Da Nang
- Vietnam
| | - Bui D. Hoi
- Department of Physics
- Hue University of Education
- Hue
- Vietnam
| | - Chuong V. Nguyen
- Department of Materials Science and Engineering
- Le Quy Don Technical University
- 100000 Ha Noi
- Vietnam
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39
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Tong Y, Guo Y, Mu K, Shan H, Dai J, Liu Y, Sun Z, Zhao A, Zeng XC, Wu C, Xie Y. Half-Metallic Behavior in 2D Transition Metal Dichalcogenides Nanosheets by Dual-Native-Defects Engineering. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1703123. [PMID: 28861927 DOI: 10.1002/adma.201703123] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 07/30/2017] [Indexed: 06/07/2023]
Abstract
Two-dimensional transition metal dichalcogenides (TMDs) have been regarded as one of the best nonartificial low-dimensional building blocks for developing spintronic nanodevices. However, the lack of spin polarization in the vicinity of the Fermi surface and local magnetic moment in pristine TMDs has greatly hampered the exploitation of magnetotransport properties. Herein, a half-metallic structure of TMDs is successfully developed by a simple chemical defect-engineering strategy. Dual native defects decorate titanium diselenides with the coexistence of metal-Ti-atom incorporation and Se-anion defects, resulting in a high-spin-polarized current and local magnetic moment of 2D Ti-based TMDs toward half-metallic room-temperature ferromagnetism character. Arising from spin-polarization transport, the as-obtained T-TiSe1.8 nanosheets exhibit a large negative magnetoresistance phenomenon with a value of -40% (5T, 10 K), representing one of the highest negative magnetoresistance effects among TMDs. It is anticipated that this dual regulation strategy will be a powerful tool for optimizing the intrinsic physical properties of TMD systems.
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Affiliation(s)
- Yun Tong
- Hefei National Laboratory for Physical Science at the Microscale, CAS Center for Excellence in Nanoscience and CAS Key Laboratory of Mechanical Behavior and Design of Materials, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
| | - Yuqiao Guo
- Hefei National Laboratory for Physical Science at the Microscale, CAS Center for Excellence in Nanoscience and CAS Key Laboratory of Mechanical Behavior and Design of Materials, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
| | - Kejun Mu
- Hefei National Laboratory for Physical Science at the Microscale, CAS Center for Excellence in Nanoscience and CAS Key Laboratory of Mechanical Behavior and Design of Materials, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
| | - Huan Shan
- Hefei National Laboratory for Physical Science at the Microscale, CAS Center for Excellence in Nanoscience and CAS Key Laboratory of Mechanical Behavior and Design of Materials, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
| | - Jun Dai
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA
| | - Yi Liu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
| | - Zhe Sun
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
| | - Aidi Zhao
- Hefei National Laboratory for Physical Science at the Microscale, CAS Center for Excellence in Nanoscience and CAS Key Laboratory of Mechanical Behavior and Design of Materials, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
| | - Xiao Cheng Zeng
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA
| | - Changzheng Wu
- Hefei National Laboratory for Physical Science at the Microscale, CAS Center for Excellence in Nanoscience and CAS Key Laboratory of Mechanical Behavior and Design of Materials, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
| | - Yi Xie
- Hefei National Laboratory for Physical Science at the Microscale, CAS Center for Excellence in Nanoscience and CAS Key Laboratory of Mechanical Behavior and Design of Materials, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
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40
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Gehlmann M, Aguilera I, Bihlmayer G, Nemšák S, Nagler P, Gospodarič P, Zamborlini G, Eschbach M, Feyer V, Kronast F, Młyńczak E, Korn T, Plucinski L, Schüller C, Blügel S, Schneider CM. Direct Observation of the Band Gap Transition in Atomically Thin ReS 2. NANO LETTERS 2017; 17:5187-5192. [PMID: 28759250 DOI: 10.1021/acs.nanolett.7b00627] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
ReS2 is considered as a promising candidate for novel electronic and sensor applications. The low crystal symmetry of this van der Waals compound leads to a highly anisotropic optical, vibrational, and transport behavior. However, the details of the electronic band structure of this fascinating material are still largely unexplored. We present a momentum-resolved study of the electronic structure of monolayer, bilayer, and bulk ReS2 using k-space photoemission microscopy in combination with first-principles calculations. We demonstrate that the valence electrons in bulk ReS2 are-contrary to assumptions in recent literature-significantly delocalized across the van der Waals gap. Furthermore, we directly observe the evolution of the valence band dispersion as a function of the number of layers, revealing the transition from an indirect band gap in bulk ReS2 to a direct gap in the bilayer and the monolayer. We also find a significantly increased effective hole mass in single-layer crystals. Our results establish bilayer ReS2 as an advantageous building block for two-dimensional devices and van der Waals heterostructures.
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Affiliation(s)
- Mathias Gehlmann
- Peter Grünberg Institut PGI-6, Forschungszentrum Jülich and JARA , 52425 Jülich, Germany
| | - Irene Aguilera
- Peter Grünberg Institut PGI-1 and Institute for Advanced Simulation IAS-1, Forschungszentrum Jülich and JARA , 52425 Jülich, Germany
| | - Gustav Bihlmayer
- Peter Grünberg Institut PGI-1 and Institute for Advanced Simulation IAS-1, Forschungszentrum Jülich and JARA , 52425 Jülich, Germany
| | - Slavomír Nemšák
- Peter Grünberg Institut PGI-6, Forschungszentrum Jülich and JARA , 52425 Jülich, Germany
| | - Philipp Nagler
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg , 93053 Regensburg, Germany
| | - Pika Gospodarič
- Peter Grünberg Institut PGI-6, Forschungszentrum Jülich and JARA , 52425 Jülich, Germany
| | - Giovanni Zamborlini
- Peter Grünberg Institut PGI-6, Forschungszentrum Jülich and JARA , 52425 Jülich, Germany
| | - Markus Eschbach
- Peter Grünberg Institut PGI-6, Forschungszentrum Jülich and JARA , 52425 Jülich, Germany
| | - Vitaliy Feyer
- Peter Grünberg Institut PGI-6, Forschungszentrum Jülich and JARA , 52425 Jülich, Germany
| | - Florian Kronast
- Abteilung Materialien für grüne Spintronik, Helmholtz-Zentrum Berlin , 14109 Berlin, Germany
| | - Ewa Młyńczak
- Peter Grünberg Institut PGI-6, Forschungszentrum Jülich and JARA , 52425 Jülich, Germany
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology , 30-059 Kraków, Poland
| | - Tobias Korn
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg , 93053 Regensburg, Germany
| | - Lukasz Plucinski
- Peter Grünberg Institut PGI-6, Forschungszentrum Jülich and JARA , 52425 Jülich, Germany
| | - Christian Schüller
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg , 93053 Regensburg, Germany
| | - Stefan Blügel
- Peter Grünberg Institut PGI-1 and Institute for Advanced Simulation IAS-1, Forschungszentrum Jülich and JARA , 52425 Jülich, Germany
| | - Claus M Schneider
- Peter Grünberg Institut PGI-6, Forschungszentrum Jülich and JARA , 52425 Jülich, Germany
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41
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Chen C, Avila J, Asensio MC. Chemical and electronic structure imaging of graphene on Cu: a NanoARPES study. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:183001. [PMID: 28260698 DOI: 10.1088/1361-648x/aa6487] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Electronic structure, which describes the distribution of electronic states in reciprocal space, is one of the most fundamental concepts in condensed matter physics, since it determines the electrical, optical and magnetic behaviours of materials. Graphene has great promise for both fundamental physics and future applications. Chemical vapour deposition (CVD) is currently the dominant technology for its scaled growth on metal foils. The polycrystalline nature of metal foil makes NanoARPES, one energy-momentum dispersion probe with spatial resolution down to a few tens of nanometers, a unique tool to study the intrinsic electronic structure of polycrystalline graphene films. In this topical review, we present the latest NanoARPES studies on graphene grains and films grown on copper foil by CVD. The comprehensive chemical and electronic images probed by NanoARPES provide deep insight about graphene and point out potential ways to functionalize graphene properties. This knowledge may stimulate us to look into the future of this field from both the material synthesis and the instrumental characterisation.
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Affiliation(s)
- Chaoyu Chen
- ANTARES Beamline, Synchrotron SOLEIL, Université Paris-Saclay, L'Orme des Merisiers, Saint Aubin-BP 48, 91192 Gif sur Yvette Cedex, France
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42
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Mo SK. Angle-resolved photoemission spectroscopy for the study of two-dimensional materials. NANO CONVERGENCE 2017; 4:6. [PMCID: PMC6141890 DOI: 10.1186/s40580-017-0100-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 03/15/2017] [Indexed: 05/26/2023]
Abstract
Quantum systems in confined geometries allow novel physical properties that cannot easily be attained in their bulk form. These properties are governed by the changes in the band structure and the lattice symmetry, and most pronounced in their single layer limit. Angle-resolved photoemission spectroscopy (ARPES) is a direct tool to investigate the underlying changes of band structure to provide essential information for understanding and controlling such properties. In this review, recent progresses in ARPES as a tool to study two-dimensional atomic crystals have been presented. ARPES results from few-layer and bulk crystals of material class often referred as “beyond graphene” are discussed along with the relevant developments in the instrumentation.
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Affiliation(s)
- Sung-Kwan Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
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43
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Pierucci D, Henck H, Ben Aziza Z, Naylor CH, Balan A, Rault JE, Silly MG, Dappe YJ, Bertran F, Le Fèvre P, Sirotti F, Johnson ATC, Ouerghi A. Tunable Doping in Hydrogenated Single Layered Molybdenum Disulfide. ACS NANO 2017; 11:1755-1761. [PMID: 28146631 DOI: 10.1021/acsnano.6b07661] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Structural defects in the molybdenum disulfide (MoS2) monolayer are widely known for strongly altering its properties. Therefore, a deep understanding of these structural defects and how they affect MoS2 electronic properties is of fundamental importance. Here, we report on the incorporation of atomic hydrogen in monolayered MoS2 to tune its structural defects. We demonstrate that the electronic properties of single layer MoS2 can be tuned from the intrinsic electron (n) to hole (p) doping via controlled exposure to atomic hydrogen at room temperature. Moreover, this hydrogenation process represents a viable technique to completely saturate the sulfur vacancies present in the MoS2 flakes. The successful incorporation of hydrogen in MoS2 leads to the modification of the electronic properties as evidenced by high resolution X-ray photoemission spectroscopy and density functional theory calculations. Micro-Raman spectroscopy and angle resolved photoemission spectroscopy measurements show the high quality of the hydrogenated MoS2 confirming the efficiency of our hydrogenation process. These results demonstrate that the MoS2 hydrogenation could be a significant and efficient way to achieve tunable doping of transition metal dichalcogenides (TMD) materials with non-TMD elements.
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Affiliation(s)
- Debora Pierucci
- Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Université Paris-Saclay , C2N - Marcoussis, F91460 Marcoussis, France
| | - Hugo Henck
- Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Université Paris-Saclay , C2N - Marcoussis, F91460 Marcoussis, France
| | - Zeineb Ben Aziza
- Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Université Paris-Saclay , C2N - Marcoussis, F91460 Marcoussis, France
| | - Carl H Naylor
- Department of Physics and Astronomy, University of Pennsylvania , 209S 33rd Street, Philadelphia, Pennsylvania 19104, United States
| | - Adrian Balan
- Department of Physics and Astronomy, University of Pennsylvania , 209S 33rd Street, Philadelphia, Pennsylvania 19104, United States
| | - Julien E Rault
- Synchrotron-SOLEIL , Saint-Aubin, BP48, F91192 Gif sur Yvette Cedex, France
| | - Mathieu G Silly
- Synchrotron-SOLEIL , Saint-Aubin, BP48, F91192 Gif sur Yvette Cedex, France
| | - Yannick J Dappe
- SPEC, CEA, CNRS, Université Paris-Saclay , CEA Saclay, F91191 Gif-sur-Yvette Cedex, France
| | - François Bertran
- Synchrotron-SOLEIL , Saint-Aubin, BP48, F91192 Gif sur Yvette Cedex, France
| | - Patrick Le Fèvre
- Synchrotron-SOLEIL , Saint-Aubin, BP48, F91192 Gif sur Yvette Cedex, France
| | - Fausto Sirotti
- Synchrotron-SOLEIL , Saint-Aubin, BP48, F91192 Gif sur Yvette Cedex, France
| | - A T Charlie Johnson
- Department of Physics and Astronomy, University of Pennsylvania , 209S 33rd Street, Philadelphia, Pennsylvania 19104, United States
| | - Abdelkarim Ouerghi
- Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Université Paris-Saclay , C2N - Marcoussis, F91460 Marcoussis, France
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44
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Wilson NR, Nguyen PV, Seyler K, Rivera P, Marsden AJ, Laker ZP, Constantinescu GC, Kandyba V, Barinov A, Hine ND, Xu X, Cobden DH. Determination of band offsets, hybridization, and exciton binding in 2D semiconductor heterostructures. SCIENCE ADVANCES 2017; 3:e1601832. [PMID: 28246636 PMCID: PMC5298850 DOI: 10.1126/sciadv.1601832] [Citation(s) in RCA: 127] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 12/19/2016] [Indexed: 05/21/2023]
Abstract
Combining monolayers of different two-dimensional semiconductors into heterostructures creates new phenomena and device possibilities. Understanding and exploiting these phenomena hinge on knowing the electronic structure and the properties of interlayer excitations. We determine the key unknown parameters in MoSe2/WSe2 heterobilayers by using rational device design and submicrometer angle-resolved photoemission spectroscopy (μ-ARPES) in combination with photoluminescence. We find that the bands in the K-point valleys are weakly hybridized, with a valence band offset of 300 meV, implying type II band alignment. We deduce that the binding energy of interlayer excitons is more than 200 meV, an order of magnitude higher than that in analogous GaAs structures. Hybridization strongly modifies the bands at Γ, but the valence band edge remains at the K points. We also find that the spectrum of a rotationally aligned heterobilayer reflects a mixture of commensurate and incommensurate domains. These results directly answer many outstanding questions about the electronic nature of MoSe2/WSe2 heterobilayers and demonstrate a practical approach for high spectral resolution in ARPES of device-scale structures.
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Affiliation(s)
- Neil R. Wilson
- Department of Physics, University of Warwick, Coventry CV4 7AL, U.K
- Corresponding author. (D.H.C.); (N.R.W.); (X.X.)
| | - Paul V. Nguyen
- Department of Physics, University of Washington, Seattle, WA 98195, USA
| | - Kyle Seyler
- Department of Physics, University of Washington, Seattle, WA 98195, USA
| | - Pasqual Rivera
- Department of Physics, University of Washington, Seattle, WA 98195, USA
| | | | | | - Gabriel C. Constantinescu
- Theory of Condensed Matter Group, Cavendish Laboratory, University of Cambridge, 19 JJ Thomson Avenue, Cambridge CB3 0HE, U.K
| | - Viktor Kandyba
- Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, 34149 Trieste, Italy
- Physics Department, University of Trieste, Via Valerio 2, 34127 Trieste, Italy
| | - Alexei Barinov
- Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, 34149 Trieste, Italy
| | | | - Xiaodong Xu
- Department of Physics, University of Washington, Seattle, WA 98195, USA
- Department of Materials Science and Engineering, University of Washington, Seattle, WA 98195, USA
- Corresponding author. (D.H.C.); (N.R.W.); (X.X.)
| | - David H. Cobden
- Department of Physics, University of Washington, Seattle, WA 98195, USA
- Corresponding author. (D.H.C.); (N.R.W.); (X.X.)
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45
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Quantifying electronic band interactions in van der Waals materials using angle-resolved reflected-electron spectroscopy. Nat Commun 2016; 7:13621. [PMID: 27897180 PMCID: PMC5141287 DOI: 10.1038/ncomms13621] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 10/17/2016] [Indexed: 11/10/2022] Open
Abstract
High electron mobility is one of graphene's key properties, exploited for applications and fundamental research alike. Highest mobility values are found in heterostructures of graphene and hexagonal boron nitride, which consequently are widely used. However, surprisingly little is known about the interaction between the electronic states of these layered systems. Rather pragmatically, it is assumed that these do not couple significantly. Here we study the unoccupied band structure of graphite, boron nitride and their heterostructures using angle-resolved reflected-electron spectroscopy. We demonstrate that graphene and boron nitride bands do not interact over a wide energy range, despite their very similar dispersions. The method we use can be generally applied to study interactions in van der Waals systems, that is, artificial stacks of layered materials. With this we can quantitatively understand the ‘chemistry of layers' by which novel materials are created via electronic coupling between the layers they are composed of. Heterostructures of graphene and hexagonal boron nitride have great potential for high-mobility electronics, yet little is known about the electronic interaction between these two atomically thin materials. Here, the authors perform angle-resolved reflected-electron spectroscopy to unveil their interplay.
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46
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Dirac Cones in Graphene, Interlayer Interaction in Layered Materials, and the Band Gap in MoS2. CRYSTALS 2016. [DOI: 10.3390/cryst6110143] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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47
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Van Der Waals Heterostructures between Small Organic Molecules and Layered Substrates. CRYSTALS 2016. [DOI: 10.3390/cryst6090113] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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48
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Arango YC, Huang L, Chen C, Avila J, Asensio MC, Grützmacher D, Lüth H, Lu JG, Schäpers T. Quantum Transport and Nano Angle-resolved Photoemission Spectroscopy on the Topological Surface States of Single Sb2Te3 Nanowires. Sci Rep 2016; 6:29493. [PMID: 27581169 PMCID: PMC5007488 DOI: 10.1038/srep29493] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 06/07/2016] [Indexed: 11/09/2022] Open
Abstract
We report on low-temperature transport and electronic band structure of p-type Sb2Te3 nanowires, grown by chemical vapor deposition. Magnetoresistance measurements unravel quantum interference phenomena, which depend on the cross-sectional dimensions of the nanowires. The observation of periodic Aharonov-Bohm-type oscillations is attributed to transport in topologically protected surface states in the Sb2Te3 nanowires. The study of universal conductance fluctuations demonstrates coherent transport along the Aharonov-Bohm paths encircling the rectangular cross-section of the nanowires. We use nanoscale angle-resolved photoemission spectroscopy on single nanowires (nano-ARPES) to provide direct experimental evidence on the nontrivial topological character of those surface states. The compiled study of the bandstructure and the magnetotransport response unambiguosly points out the presence of topologically protected surface states in the nanowires and their substantial contribution to the quantum transport effects, as well as the hole doping and Fermi velocity among other key issues. The results are consistent with the theoretical description of quantum transport in intrinsically doped quasi-one-dimensional topological insulator nanowires.
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Affiliation(s)
- Yulieth C Arango
- Peter Grünberg Institute (PGI-9) and JARA Jülich-Aachen Research Alliance, Research Centre Jülich GmbH, 52425 Jülich, Germany
| | - Liubing Huang
- Department of Physics and Astronomy and Department of Electrophysics, University of Southern California, CA 90089, Los Angeles, USA
| | - Chaoyu Chen
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin-BP 48, Gif sur Yvette 91192, France
| | - Jose Avila
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin-BP 48, Gif sur Yvette 91192, France
| | - Maria C Asensio
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin-BP 48, Gif sur Yvette 91192, France
| | - Detlev Grützmacher
- Peter Grünberg Institute (PGI-9) and JARA Jülich-Aachen Research Alliance, Research Centre Jülich GmbH, 52425 Jülich, Germany
| | - Hans Lüth
- Peter Grünberg Institute (PGI-9) and JARA Jülich-Aachen Research Alliance, Research Centre Jülich GmbH, 52425 Jülich, Germany
| | - Jia Grace Lu
- Department of Physics and Astronomy and Department of Electrophysics, University of Southern California, CA 90089, Los Angeles, USA.,Peter Grünberg Institute (PGI-9) and JARA Jülich-Aachen Research Alliance, Research Centre Jülich GmbH, 52425 Jülich, Germany
| | - Thomas Schäpers
- Peter Grünberg Institute (PGI-9) and JARA Jülich-Aachen Research Alliance, Research Centre Jülich GmbH, 52425 Jülich, Germany
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49
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Pierucci D, Henck H, Avila J, Balan A, Naylor CH, Patriarche G, Dappe YJ, Silly MG, Sirotti F, Johnson ATC, Asensio MC, Ouerghi A. Band Alignment and Minigaps in Monolayer MoS2-Graphene van der Waals Heterostructures. NANO LETTERS 2016; 16:4054-4061. [PMID: 27281693 DOI: 10.1021/acs.nanolett.6b00609] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Two-dimensional layered MoS2 shows great potential for nanoelectronic and optoelectronic devices due to its high photosensitivity, which is the result of its indirect to direct band gap transition when the bulk dimension is reduced to a single monolayer. Here, we present an exhaustive study of the band alignment and relativistic properties of a van der Waals heterostructure formed between single layers of MoS2 and graphene. A sharp, high-quality MoS2-graphene interface was obtained and characterized by micro-Raman spectroscopy, high-resolution X-ray photoemission spectroscopy (HRXPS), and scanning high-resolution transmission electron microscopy (STEM/HRTEM). Moreover, direct band structure determination of the MoS2/graphene van der Waals heterostructure monolayer was carried out using angle-resolved photoemission spectroscopy (ARPES), shedding light on essential features such as doping, Fermi velocity, hybridization, and band-offset of the low energy electronic dynamics found at the interface. We show that, close to the Fermi level, graphene exhibits a robust, almost perfect, gapless, and n-doped Dirac cone and no significant charge transfer doping is detected from MoS2 to graphene. However, modification of the graphene band structure occurs at rather larger binding energies, as the opening of several miniband-gaps is observed. These miniband-gaps resulting from the overlay of MoS2 and the graphene layer lattice impose a superperiodic potential.
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Affiliation(s)
- Debora Pierucci
- Centre de Nanosciences et de Nanotechnologies, CNRS Univ. Paris-Sud, Université Paris-Saclay , C2N - Marcoussis, 91460 Marcoussis, France
| | - Hugo Henck
- Centre de Nanosciences et de Nanotechnologies, CNRS Univ. Paris-Sud, Université Paris-Saclay , C2N - Marcoussis, 91460 Marcoussis, France
| | - Jose Avila
- Synchrotron-SOLEIL , Saint-Aubin, BP48, F91192 Gif sur Yvette Cedex, France
| | - Adrian Balan
- Department of Physics and Astronomy, University of Pennsylvania , 209S 33rd Street, Philadelphia, Pennsylvania 19104 6396, United States
- LICSEN, NIMBE, CEA, CNRS, Université Paris Saclay , CEA Saclay, 91191 Gif-sur-Yvette, France
| | - Carl H Naylor
- Department of Physics and Astronomy, University of Pennsylvania , 209S 33rd Street, Philadelphia, Pennsylvania 19104 6396, United States
| | - Gilles Patriarche
- Centre de Nanosciences et de Nanotechnologies, CNRS Univ. Paris-Sud, Université Paris-Saclay , C2N - Marcoussis, 91460 Marcoussis, France
| | - Yannick J Dappe
- SPEC, CEA, CNRS, Université Paris Saclay , CEA Saclay, 91191 Gif-sur-Yvette Cedex, France
| | - Mathieu G Silly
- Synchrotron-SOLEIL , Saint-Aubin, BP48, F91192 Gif sur Yvette Cedex, France
| | - Fausto Sirotti
- Synchrotron-SOLEIL , Saint-Aubin, BP48, F91192 Gif sur Yvette Cedex, France
| | - A T Charlie Johnson
- Department of Physics and Astronomy, University of Pennsylvania , 209S 33rd Street, Philadelphia, Pennsylvania 19104 6396, United States
| | - Maria C Asensio
- Synchrotron-SOLEIL , Saint-Aubin, BP48, F91192 Gif sur Yvette Cedex, France
| | - Abdelkarim Ouerghi
- Centre de Nanosciences et de Nanotechnologies, CNRS Univ. Paris-Sud, Université Paris-Saclay , C2N - Marcoussis, 91460 Marcoussis, France
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50
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Pierucci D, Henck H, Naylor CH, Sediri H, Lhuillier E, Balan A, Rault JE, Dappe YJ, Bertran F, Fèvre PL, Johnson ATC, Ouerghi A. Large area molybdenum disulphide- epitaxial graphene vertical Van der Waals heterostructures. Sci Rep 2016; 6:26656. [PMID: 27246929 PMCID: PMC4894673 DOI: 10.1038/srep26656] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 05/03/2016] [Indexed: 11/09/2022] Open
Abstract
Two-dimensional layered transition metal dichalcogenides (TMDCs) show great potential for optoelectronic devices due to their electronic and optical properties. A metal-semiconductor interface, as epitaxial graphene - molybdenum disulfide (MoS2), is of great interest from the standpoint of fundamental science, as it constitutes an outstanding platform to investigate the interlayer interaction in van der Waals heterostructures. Here, we study large area MoS2-graphene-heterostructures formed by direct transfer of chemical-vapor deposited MoS2 layer onto epitaxial graphene/SiC. We show that via a direct transfer, which minimizes interface contamination, we can obtain high quality and homogeneous van der Waals heterostructures. Angle-resolved photoemission spectroscopy (ARPES) measurements combined with Density Functional Theory (DFT) calculations show that the transition from indirect to direct bandgap in monolayer MoS2 is maintained in these heterostructures due to the weak van der Waals interaction with epitaxial graphene. A downshift of the Raman 2D band of the graphene, an up shift of the A1g peak of MoS2 and a significant photoluminescence quenching are observed for both monolayer and bilayer MoS2 as a result of charge transfer from MoS2 to epitaxial graphene under illumination. Our work provides a possible route to modify the thin film TDMCs photoluminescence properties via substrate engineering for future device design.
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Affiliation(s)
- Debora Pierucci
- Laboratoire de Photonique et de Nanostructures (CNRS- LPN),
Route de Nozay, 91460
Marcoussis, France
| | - Hugo Henck
- Laboratoire de Photonique et de Nanostructures (CNRS- LPN),
Route de Nozay, 91460
Marcoussis, France
| | - Carl H. Naylor
- Department of Physics and Astronomy, University of
Pennsylvania, 209S 33rd Street, Philadelphia,
Pennsylvania
19104, USA
| | - Haikel Sediri
- Laboratoire de Photonique et de Nanostructures (CNRS- LPN),
Route de Nozay, 91460
Marcoussis, France
| | - Emmanuel Lhuillier
- Institut des Nanosciences de Paris, UPMC, 4 place Jussieu,
boîte courrier 840, 75252
Paris cedex 05, France
| | - Adrian Balan
- Department of Physics and Astronomy, University of
Pennsylvania, 209S 33rd Street, Philadelphia,
Pennsylvania
19104, USA
- Laboratoire d’Innovation en Chimie des Surfaces et
Nanosciences, DSM/NIMBE/LICSEN (CNRS UMR 3685), CEA Saclay,
91191
Gif-sur-Yvette Cedex, France
| | - Julien E. Rault
- Synchrotron-SOLEIL, Saint-Aubin, BP48,
F91192 Gif sur Yvette Cedex, France
| | - Yannick J. Dappe
- SPEC, CEA, CNRS, Universite Paris-Saclay, CEA Saclay,
91191 Gif-sur-Yvette Cedex, France
| | - François Bertran
- Synchrotron-SOLEIL, Saint-Aubin, BP48,
F91192 Gif sur Yvette Cedex, France
| | - Patrick Le Fèvre
- Synchrotron-SOLEIL, Saint-Aubin, BP48,
F91192 Gif sur Yvette Cedex, France
| | - A. T. Charlie Johnson
- Department of Physics and Astronomy, University of
Pennsylvania, 209S 33rd Street, Philadelphia,
Pennsylvania
19104, USA
| | - Abdelkarim Ouerghi
- Laboratoire de Photonique et de Nanostructures (CNRS- LPN),
Route de Nozay, 91460
Marcoussis, France
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