1
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Dosenovic D, Dechamps S, Sharma K, Rouviere JL, Lu Y, den Hertog MI, Genovese L, Dubois SMM, Charlier JC, Jamet M, Marty A, Okuno H. Imaging Negative Charge around Single Vanadium Dopant Atoms in Monolayer Tungsten Diselenide Using 4D Scanning Transmission Electron Microscopy. ACS NANO 2024; 18:23354-23364. [PMID: 39145421 DOI: 10.1021/acsnano.4c06561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/16/2024]
Abstract
There has been extensive activity exploring the doping of semiconducting two-dimensional (2D) transition metal dichalcogenides in order to tune their electronic and magnetic properties. The outcome of doping depends on various factors, including the intrinsic properties of the host material, the nature of the dopants used, their spatial distribution, as well as their interactions with other types of defects. A thorough atomic-level analysis is essential to fully understand these mechanisms. In this work, the vanadium-doped WSe2 monolayer grown by molecular beam epitaxy is investigated using four-dimensional scanning transmission electron microscopy (4D-STEM). Through center-of-mass-based reconstruction, atomic-scale maps are produced, allowing the visualization of both the electric field and the electrostatic potential around individual V atoms. To provide quantitative insights, these results are successfully compared to multislice image simulations based on ab initio calculations, accounting for lens aberrations. Finally, a negative charge around the V dopants is detected as a drop in the electrostatic potential, unambiguously demonstrating that 4D-STEM can be used to detect and to accurately analyze single-dopant charge states in semiconducting 2D materials.
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Affiliation(s)
| | - Samuel Dechamps
- Univ. Grenoble Alpes, CEA, IRIG-MEM, 38000 Grenoble, France
- Institute of Condensed Matter and Nanosciences, Université catholique de Louvain (UCLouvain), 1348 Louvain-la-Neuve, Belgium
| | - Kshipra Sharma
- Univ. Grenoble Alpes, CEA, IRIG-MEM, 38000 Grenoble, France
| | | | - Yiran Lu
- Univ. Grenoble Alpes, CNRS-Institut Néel, F-38000 Grenoble, France
| | | | - Luigi Genovese
- Univ. Grenoble Alpes, CEA, IRIG-MEM, 38000 Grenoble, France
| | - Simon Mutien-Marie Dubois
- Institute of Condensed Matter and Nanosciences, Université catholique de Louvain (UCLouvain), 1348 Louvain-la-Neuve, Belgium
| | - Jean-Christophe Charlier
- Institute of Condensed Matter and Nanosciences, Université catholique de Louvain (UCLouvain), 1348 Louvain-la-Neuve, Belgium
| | - Matthieu Jamet
- Univ. Grenoble Alpes, CEA, CNRS, Grenoble INP, IRIG-SPINTEC, 38000 Grenoble, France
| | - Alain Marty
- Univ. Grenoble Alpes, CEA, CNRS, Grenoble INP, IRIG-SPINTEC, 38000 Grenoble, France
| | - Hanako Okuno
- Univ. Grenoble Alpes, CEA, IRIG-MEM, 38000 Grenoble, France
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2
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Stolz S, Hou B, Wang D, Kozhakhmetov A, Dong C, Gröning O, Robinson JA, Qiu DY, Schuler B. Spin-Stabilization by Coulomb Blockade in a Vanadium Dimer in WSe 2. ACS NANO 2023. [PMID: 37976219 DOI: 10.1021/acsnano.3c04841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
Abstract
Charged dopants in 2D transition metal dichalcogenides (TMDs) have been associated with the formation of hydrogenic bound states, defect-bound trions, and gate-controlled magnetism. Charge-transfer at the TMD-substrate interface and the proximity to other charged defects can be used to regulate the occupation of the dopant's energy levels. In this study, we examine vanadium-doped WSe2 monolayers on quasi-freestanding epitaxial graphene, by high-resolution scanning probe microscopy and ab initio calculations. Vanadium atoms substitute W atoms and adopt a negative charge state through charge donation from the graphene substrate. VW-1 dopants exhibit a series of occupied p-type defect states, accompanied by an intriguing electronic fine-structure that we attribute to hydrogenic states bound to the charged impurity. We systematically studied the hybridization in V dimers with different separations. For large dimer separations, the 2e- charge state prevails, and the magnetic moment is quenched. However, the Coulomb blockade in the nearest-neighbor dimer configuration stabilizes a 1e- charge state. The nearest-neighbor V-dimer exhibits an open-shell character for the frontier defect orbital, giving rise to a paramagnetic ground state. Our findings provide microscopic insights into the charge stabilization and many-body effects of single dopants and dopant pairs in a TMD host material.
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Affiliation(s)
- Samuel Stolz
- nanotech@surfaces Laboratory, Empa - Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
- Department of Physics, University of California, Berkeley, California 94720, United States
| | - Bowen Hou
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06511, United States
| | - Dan Wang
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06511, United States
| | - Azimkhan Kozhakhmetov
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16082, United States
- Two-Dimensional Crystal Consortium, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Chengye Dong
- Two-Dimensional Crystal Consortium, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Oliver Gröning
- nanotech@surfaces Laboratory, Empa - Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
| | - Joshua A Robinson
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16082, United States
- Two-Dimensional Crystal Consortium, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Chemistry and Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Diana Y Qiu
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06511, United States
| | - Bruno Schuler
- nanotech@surfaces Laboratory, Empa - Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
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3
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Vu NTT, Loh L, Chen Y, Wu Q, Verzhbitskiy IA, Watanabe K, Taniguchi T, Bosman M, Ang YS, Ang LK, Trushin M, Eda G. Single Atomic Defect Conductivity for Selective Dilute Impurity Imaging in 2D Semiconductors. ACS NANO 2023; 17:15648-15655. [PMID: 37565985 DOI: 10.1021/acsnano.3c02758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
Precisely controlled impurity doping is of fundamental significance in modern semiconductor technologies. Desired physical properties are often achieved at impurity concentrations well below parts per million level. For emergent two-dimensional semiconductors, development of reliable doping strategies is hindered by the inherent difficulty in identifying and quantifying impurities in such a dilute limit where the absolute number of atoms to be detected is insufficient for common analytical techniques. Here we report rapid high-contrast imaging of dilute single atomic impurities by using conductive atomic force microscopy. We show that the local conductivity is enhanced by more than 100-fold by a single impurity atom due to resonance-assisted tunneling. Unlike the closely related scanning tunneling microscopy, the local conductivity sensitively depends on the impurity energy level, allowing minority defects to be selectively imaged. We further demonstrate subsurface impurity detection with single monolayer depth resolution in multilayer materials.
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Affiliation(s)
- Nam Thanh Trung Vu
- Physics Department, National University of Singapore, Singapore 117551, Singapore
| | - Leyi Loh
- Physics Department, National University of Singapore, Singapore 117551, Singapore
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117575, Singapore
| | - Yuan Chen
- Chemistry Department, National University of Singapore, Singapore 117543, Singapore
| | - Qingyun Wu
- Science, Mathematics, and Technology, Singapore University of Technology and Design (SUTD), Singapore 487372, Singapore
| | - Ivan A Verzhbitskiy
- Physics Department, National University of Singapore, Singapore 117551, Singapore
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis #08-03, Singapore 138634, Singapore
| | - Kenji Watanabe
- Research Centre for Functional Materials, National Institute for Materials Science, Tsukuba 305-0047, Japan
| | - Takashi Taniguchi
- International Centre for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba 305-0047, Japan
| | - Michel Bosman
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117575, Singapore
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis #08-03, Singapore 138634, Singapore
| | - Yee Sin Ang
- Science, Mathematics, and Technology, Singapore University of Technology and Design (SUTD), Singapore 487372, Singapore
| | - Lay Kee Ang
- Science, Mathematics, and Technology, Singapore University of Technology and Design (SUTD), Singapore 487372, Singapore
| | - Maxim Trushin
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117575, Singapore
- Centre for Advanced 2D Materials, National University of Singapore, Singapore 117546, Singapore
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore 117544, Singapore
| | - Goki Eda
- Physics Department, National University of Singapore, Singapore 117551, Singapore
- Chemistry Department, National University of Singapore, Singapore 117543, Singapore
- Centre for Advanced 2D Materials, National University of Singapore, Singapore 117546, Singapore
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4
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Khalil L, Ernandes C, Avila J, Rousseau A, Dudin P, Zhigadlo ND, Cassabois G, Gil B, Oehler F, Chaste J, Ouerghi A. High p doped and robust band structure in Mg-doped hexagonal boron nitride. NANOSCALE ADVANCES 2023; 5:3225-3232. [PMID: 37325527 PMCID: PMC10262975 DOI: 10.1039/d2na00843b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 04/05/2023] [Indexed: 06/17/2023]
Abstract
In two dimensional materials, substitutional doping during growth can be used to alter the electronic properties. Here, we report on the stable growth of p-type hexagonal boron nitride (h-BN) using Mg-atoms as substitutional impurities in the h-BN honeycomb lattice. We use micro-Raman spectroscopy, angle-resolved photoemission measurements (nano-ARPES) and Kelvin probe force microscopy (KPFM) to study the electronic properties of Mg-doped h-BN grown by solidification from a ternary Mg-B-N system. Besides the observation of a new Raman line at ∼1347 cm-1 in Mg-doped h-BN, nano-ARPES reveals p-type carrier concentration. Our nano-ARPES experiments demonstrate that the Mg dopants can significantly alter the electronic properties of h-BN by shifting the valence band maximum about 150 meV toward higher binding energies with respect to pristine h-BN. We further show that, Mg doped h-BN exhibits a robust, almost unaltered, band structure compared to pristine h-BN, with no significant deformation. Kelvin probe force microscopy (KPFM) confirms the p-type doping, with a reduced Fermi level difference between pristine and Mg-doped h-BN crystals. Our findings demonstrate that conventional semiconductor doping by Mg as substitutional impurities is a promising route to high-quality p-type doped h-BN films. Such stable p-type doping of large band h-BN is a key feature for 2D materials applications in deep ultra-violet light emitting diodes or wide bandgap optoelectronic devices.
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Affiliation(s)
- Lama Khalil
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies 91120 Palaiseau France
| | - Cyrine Ernandes
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies 91120 Palaiseau France
| | - José Avila
- Université Paris-Saclay, Synchrotron SOLEIL L'Orme des Merisiers, BP48 91190 Saint-Aubin France
| | - Adrien Rousseau
- Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS 34095 Montpellier France
| | - Pavel Dudin
- Université Paris-Saclay, Synchrotron SOLEIL L'Orme des Merisiers, BP48 91190 Saint-Aubin France
| | | | - Guillaume Cassabois
- Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS 34095 Montpellier France
| | - Bernard Gil
- Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS 34095 Montpellier France
| | - Fabrice Oehler
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies 91120 Palaiseau France
| | - Julien Chaste
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies 91120 Palaiseau France
| | - Abdelkarim Ouerghi
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies 91120 Palaiseau France
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5
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Połczyńska KE, Le Denmat S, Taniguchi T, Watanabe K, Potemski M, Kossacki P, Pacuski W, Kasprzak J. Coherent imaging and dynamics of excitons in MoSe 2 monolayers epitaxially grown on hexagonal boron nitride. NANOSCALE 2023; 15:6941-6946. [PMID: 37010358 DOI: 10.1039/d2nr04844b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Using four-wave mixing microscopy, we measure the coherent response and ultrafast dynamics of excitons and trions in MoSe2 monolayers grown by molecular beam epitaxy on thin films of hexagonal boron nitride. We assess inhomogeneous and homogeneous broadenings in the transition spectral lineshape. The impact of phonons on the homogeneous dephasing is inferred via the temperature dependence of the dephasing. Four-wave mixing mapping, combined with atomic force microscopy, reveals spatial correlations between exciton oscillator strength, inhomogeneous broadening and the sample morphology. The quality of the coherent optical response of epitaxially grown transition metal dichalcogenides now becomes comparable to the samples produced by mechanical exfoliation, enabling the coherent nonlinear spectroscopy of innovative materials, like magnetic layers or Janus semiconductors.
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Affiliation(s)
| | - Simon Le Denmat
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 25 rue des Martyrs, 38000 Grenoble, France
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Kenji Watanabe
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Marek Potemski
- Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warszawa, Poland.
- Laboratoire National des Champs Magnétiques Intenses, CNRS-UGA-UPS-INSA-EMFL, 25 Av. des Martyrs, 38042 Grenoble, France
- CENTERA Labs, Institute of High Pressure Physics, PAS, PL-01-142 Warsaw, Poland
| | - Piotr Kossacki
- Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warszawa, Poland.
| | - Wojciech Pacuski
- Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warszawa, Poland.
| | - Jacek Kasprzak
- Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warszawa, Poland.
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 25 rue des Martyrs, 38000 Grenoble, France
- Walter Schottky Institut and TUM School of Natural Sciences, Technische Universität München, 85748 Garching, Germany
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6
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Su S, Liu Y, Li M, Huang H, Xue J. Long-Term Evolution of Vacancies in Large-Area Graphene. ACS OMEGA 2022; 7:36379-36386. [PMID: 36278062 PMCID: PMC9583090 DOI: 10.1021/acsomega.2c04121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 09/20/2022] [Indexed: 06/16/2023]
Abstract
Devices based on two-dimensional (2D) materials such as graphene and molybdenum disulfide have shown extraordinary potential in physics, nanotechnology, and electronics. The performances of these applications are heavily affected by defects in utilized materials. Although great efforts have been spent in studying the formation and property of various defects in 2D materials, the long-term evolution of vacancies is still unclear. Here, using a designed program based on the kinetic Monte Carlo method, we systematically investigate the vacancy evolution in monolayer graphene on a long-time and large spatial scale, focusing on the variation of the distribution of different vacancy types. In most cases, the vacancy distribution remains nearly unchanged during the whole evolution, and most of the evolution events are vacancy migrations with a few being coalescences, while it is extremely difficult for multiple vacancies to dissolve. The probabilities of different categories of vacancy evolutions are determined by their reaction rates, which, in turn, depend on corresponding energy barriers. We further study the influences of different factors such as the energy barrier for vacancy migration, coalescence, and dissociation on the evolution, and the coalescence energy barrier is found to be dominant. These findings indicate that vacancies (also subnanopores) in graphene are thermodynamically stable for a long period of time, conducive to subsequent characterizations or applications. Besides, this work provides hints to tune the ultimate vacancy distribution by changing related factors and suggests ways to study the evolution of other defects in various 2D materials.
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Affiliation(s)
- Shihao Su
- State
Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing100871, P. R. China
- CAPT,
HEDPS and IFSA, College of Engineering, Peking University, Beijing100871, P. R. China
| | - Yong Liu
- State
Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing100871, P. R. China
- CAPT,
HEDPS and IFSA, College of Engineering, Peking University, Beijing100871, P. R. China
| | - Man Li
- State
Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing100871, P. R. China
- CAPT,
HEDPS and IFSA, College of Engineering, Peking University, Beijing100871, P. R. China
| | - Huaqing Huang
- State
Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing100871, P. R. China
- CAPT,
HEDPS and IFSA, College of Engineering, Peking University, Beijing100871, P. R. China
| | - Jianming Xue
- State
Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing100871, P. R. China
- CAPT,
HEDPS and IFSA, College of Engineering, Peking University, Beijing100871, P. R. China
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7
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Kwon IS, Kwak IH, Zewdie GM, Lee SJ, Kim JY, Yoo SJ, Kim JG, Park J, Kang HS. WSe 2-VSe 2 Alloyed Nanosheets to Enhance the Catalytic Performance of Hydrogen Evolution Reaction. ACS NANO 2022; 16:12569-12579. [PMID: 35940577 DOI: 10.1021/acsnano.2c04113] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Tuning the electronic structures of transition metal dichalcogenides (TMD) is essential for their implementation in next-generation energy technologies. In this study, we synthesized composition-tuned WSe2-VSe2 (W1-xVxSe2, x = 0-1) alloyed nanosheets using a colloidal reaction. Alloying the semiconducting WSe2 with VSe2 converts the material into a metallic one, followed by a 2H-to-1T phase transition at x = 0.7. Over a wide composition range, WSe2 and VSe2 are atomically immiscible and form separate ordered domains. The miscible alloy at x = 0.1 displayed enhanced electrocatalytic activity toward the hydrogen evolution reaction (HER) in an acidic electrolyte. This trend was correlated with the d-band center via a volcano-type relationship. Spin-polarized density functional theory calculations consistently predicted the atomic immiscibility, which became more significant at the 2H-1T phase transition composition. The Gibbs free energy of H adsorption on the basal planes (Se or hole sites) and the activation barriers along the Volmer-Heyrovsky reaction pathway supported the enhanced HER performance of the alloy phase, suggesting that the dispersed V-doped structures were responsible for the best HER catalytic activity. Our study demonstrates how the atomic structure of TMD alloy nanosheets plays a crucial role in enhancing catalytic activity.
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Affiliation(s)
- Ik Seon Kwon
- Department of Advanced Materials Chemistry, Korea University, Sejong 339-700, Republic of Korea
| | - In Hye Kwak
- Department of Advanced Materials Chemistry, Korea University, Sejong 339-700, Republic of Korea
| | - Getasew Mulualem Zewdie
- Institute for Application of Advanced Materials, Jeonju University, Chonju, Chonbuk 55069, Republic of Korea
| | - Seung Jae Lee
- Department of Advanced Materials Chemistry, Korea University, Sejong 339-700, Republic of Korea
| | - Ju Yeon Kim
- Department of Advanced Materials Chemistry, Korea University, Sejong 339-700, Republic of Korea
| | - Seung Jo Yoo
- Division of Electron Microscopic Research, Korea Basic Science Institute, Daejeon 305-806, Republic of Korea
| | - Jin-Gyu Kim
- Division of Electron Microscopic Research, Korea Basic Science Institute, Daejeon 305-806, Republic of Korea
| | - Jeunghee Park
- Department of Advanced Materials Chemistry, Korea University, Sejong 339-700, Republic of Korea
| | - Hong Seok Kang
- Department of Nano and Advanced Materials, Jeonju University, Chonju, Chonbuk 55069, Republic of Korea
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8
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Wan W, Wickramaratne D, Dreher P, Harsh R, Mazin II, Ugeda MM. Nontrivial Doping Evolution of Electronic Properties in Ising-Superconducting Alloys. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2200492. [PMID: 35243698 DOI: 10.1002/adma.202200492] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 02/16/2022] [Indexed: 06/14/2023]
Abstract
Transition metal dichalcogenides offer unprecedented versatility to engineer 2D materials with tailored properties to explore novel structural and electronic phase transitions. In this work, the atomic-scale evolution of the electronic ground state of a monolayer of Nb1- δ Moδ Se2 across the entire alloy composition range (0 < δ < 1) is investigated using low-temperature (300 mK) scanning tunneling microscopy and spectroscopy (STM/STS). In particular, the atomic and electronic structure of this 2D alloy throughout the metal to semiconductor transition (monolayer NbSe2 to MoSe2 ) is studied. The measurements enable extraction of the effective doping of Mo atoms, the bandgap evolution and the band shifts, which are monotonic with δ. Furthermore, it is demonstrated that collective electronic phases (charge density wave and superconductivity) are remarkably robust against disorder and further shown that the superconducting TC changes non-monotonically with doping. This contrasting behavior in the normal and superconducting state is explained using first-principles calculations. Mo doping is shown to decrease the density of states at the Fermi level and the magnitude of pair-breaking spin fluctuations as a function of Mo content. These results paint a detailed picture of the electronic structure evolution in 2D TMD alloys, which is of utmost relevance for future 2D materials design.
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Affiliation(s)
- Wen Wan
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizábal 4, San Sebastián, 20018, Spain
| | - Darshana Wickramaratne
- Center for Computational Materials Science, U.S. Naval Research Laboratory, Washington, DC 20375, USA
| | - Paul Dreher
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizábal 4, San Sebastián, 20018, Spain
| | - Rishav Harsh
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizábal 4, San Sebastián, 20018, Spain
| | - Igor I Mazin
- Department of Physics and Astronomy, George Mason University, Fairfax, VA, 22030, USA
- Quantum Science and Engineering Center, George Mason University, Fairfax, VA, 22030, USA
| | - Miguel M Ugeda
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizábal 4, San Sebastián, 20018, Spain
- Centro de Física de Materiales (CSIC-UPV-EHU), Paseo Manuel de Lardizábal 5, San Sebastián, 20018, Spain
- Ikerbasque, Basque Foundation for Science, Bilbao, 48013, Spain
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9
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Two-dimensional materials prospects for non-volatile spintronic memories. Nature 2022; 606:663-673. [PMID: 35732761 DOI: 10.1038/s41586-022-04768-0] [Citation(s) in RCA: 63] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 04/19/2022] [Indexed: 01/12/2023]
Abstract
Non-volatile magnetic random-access memories (MRAMs), such as spin-transfer torque MRAM and next-generation spin-orbit torque MRAM, are emerging as key to enabling low-power technologies, which are expected to spread over large markets from embedded memories to the Internet of Things. Concurrently, the development and performances of devices based on two-dimensional van der Waals heterostructures bring ultracompact multilayer compounds with unprecedented material-engineering capabilities. Here we provide an overview of the current developments and challenges in regard to MRAM, and then outline the opportunities that can arise by incorporating two-dimensional material technologies. We highlight the fundamental properties of atomically smooth interfaces, the reduced material intermixing, the crystal symmetries and the proximity effects as the key drivers for possible disruptive improvements for MRAM at advanced technology nodes.
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10
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Pierucci D, Mahmoudi A, Silly M, Bisti F, Oehler F, Patriarche G, Bonell F, Marty A, Vergnaud C, Jamet M, Boukari H, Lhuillier E, Pala M, Ouerghi A. Evidence for highly p-type doping and type II band alignment in large scale monolayer WSe 2/Se-terminated GaAs heterojunction grown by molecular beam epitaxy. NANOSCALE 2022; 14:5859-5868. [PMID: 35362486 DOI: 10.1039/d2nr00458e] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Two-dimensional materials (2D) arranged in hybrid van der Waals (vdW) heterostructures provide a route toward the assembly of 2D and conventional III-V semiconductors. Here, we report the structural and electronic properties of single layer WSe2 grown by molecular beam epitaxy on Se-terminated GaAs(111)B. Reflection high-energy electron diffraction images exhibit sharp streaky features indicative of a high-quality WSe2 layer produced via vdW epitaxy. This is confirmed by in-plane X-ray diffraction. The single layer of WSe2 and the absence of interdiffusion at the interface are confirmed by high resolution X-ray photoemission spectroscopy and high-resolution transmission microscopy. Angle-resolved photoemission investigation revealed a well-defined WSe2 band dispersion and a high p-doping coming from the charge transfer between the WSe2 monolayer and the Se-terminated GaAs substrate. By comparing our results with local and hybrid functionals theoretical calculation, we find that the top of the valence band of the experimental heterostructure is close to the calculations for free standing single layer WSe2. Our experiments demonstrate that the proximity of the Se-terminated GaAs substrate can significantly tune the electronic properties of WSe2. The valence band maximum (VBM, located at the K point of the Brillouin zone) presents an upshift of about 0.56 eV toward the Fermi level with respect to the VBM of the WSe2 on graphene layer, which is indicative of high p-type doping and a key feature for applications in nanoelectronics and optoelectronics.
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Affiliation(s)
- Debora Pierucci
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120, Palaiseau, France.
| | - Aymen Mahmoudi
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120, Palaiseau, France.
| | - Mathieu Silly
- Synchrotron-SOLEIL, Université Paris-Saclay, Saint-Aubin, BP48, F91192 Gif sur Yvette, France
| | - Federico Bisti
- Dipartimento di Scienze Fisiche e Chimiche, Università dell'Aquila, Via Vetoio 10, 67100 L'Aquila, Italy
| | - Fabrice Oehler
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120, Palaiseau, France.
| | - Gilles Patriarche
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120, Palaiseau, France.
| | - Frédéric Bonell
- Université Grenoble Alpes, CNRS, CEA, Grenoble INP, IRIG-Spintec, 38054, Grenoble, France
| | - Alain Marty
- Université Grenoble Alpes, CNRS, CEA, Grenoble INP, IRIG-Spintec, 38054, Grenoble, France
| | - Céline Vergnaud
- Université Grenoble Alpes, CNRS, CEA, Grenoble INP, IRIG-Spintec, 38054, Grenoble, France
| | - Matthieu Jamet
- Université Grenoble Alpes, CNRS, CEA, Grenoble INP, IRIG-Spintec, 38054, Grenoble, France
| | - Hervé Boukari
- Université Grenoble Alpes, CNRS and Grenoble INP, Institut Néel, F-38000 Grenoble, France
| | - Emmanuel Lhuillier
- Sorbonne Université, CNRS, Institut des NanoSciences de Paris, INSP, F-75005 Paris, France
| | - Marco Pala
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120, Palaiseau, France.
| | - Abdelkarim Ouerghi
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120, Palaiseau, France.
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11
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Duan H, Wang C, Li G, Tan H, Hu W, Cai L, Liu W, Li N, Ji Q, Wang Y, Lu Y, Yan W, Hu F, Zhang W, Sun Z, Qi Z, Song L, Wei S. Single-Atom-Layer Catalysis in a MoS 2 Monolayer Activated by Long-Range Ferromagnetism for the Hydrogen Evolution Reaction: Beyond Single-Atom Catalysis. Angew Chem Int Ed Engl 2021; 60:7251-7258. [PMID: 33400363 DOI: 10.1002/anie.202014968] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Indexed: 11/07/2022]
Abstract
Single-atom-layer catalysts with fully activated basal-atoms will provide a solution to the low loading-density bottleneck of single-atom catalysts. Herein, we activate the majority of the basal sites of monolayer MoS2 , by doping Co ions to induce long-range ferromagnetic order. This strategy, as revealed by in situ synchrotron radiation microscopic infrared spectroscopy and electrochemical measurements, could activate more than 50 % of the originally inert basal-plane S atoms in the ferromagnetic monolayer for the hydrogen evolution reaction (HER). Consequently, on a single monolayer of ferromagnetic MoS2 measured by on-chip micro-cell, a current density of 10 mA cm-2 could be achieved at the overpotential of 137 mV, corresponding to a mass activity of 28, 571 Ag-1 , which is two orders of magnitude higher than the multilayer counterpart. Its exchange current density of 75 μA cm-2 also surpasses most other MoS2 -based catalysts. Experimental results and theoretical calculations show the activation of basal plane S atoms arises from an increase of electronic density around the Fermi level, promoting the H adsorption ability of basal-plane S atoms.
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Affiliation(s)
- Hengli Duan
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, 230029, Hefei, Anhui, China
| | - Chao Wang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, 230029, Hefei, Anhui, China
| | - Guinan Li
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, 230029, Hefei, Anhui, China
| | - Hao Tan
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, 230029, Hefei, Anhui, China
| | - Wei Hu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, 230029, Hefei, Anhui, China
| | - Liang Cai
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, 230029, Hefei, Anhui, China
| | - Wei Liu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, 230029, Hefei, Anhui, China
| | - Na Li
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, 230029, Hefei, Anhui, China
| | - Qianqian Ji
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, 230029, Hefei, Anhui, China
| | - Yao Wang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, 230029, Hefei, Anhui, China
| | - Ying Lu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, 230029, Hefei, Anhui, China
| | - Wensheng Yan
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, 230029, Hefei, Anhui, China
| | - Fengchun Hu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, 230029, Hefei, Anhui, China
| | - Wenhua Zhang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, 230029, Hefei, Anhui, China
| | - Zhihu Sun
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, 230029, Hefei, Anhui, China
| | - Zeming Qi
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, 230029, Hefei, Anhui, China
| | - Li Song
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, 230029, Hefei, Anhui, China
| | - Shiqiang Wei
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, 230029, Hefei, Anhui, China
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12
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Duan H, Wang C, Li G, Tan H, Hu W, Cai L, Liu W, Li N, Ji Q, Wang Y, Lu Y, Yan W, Hu F, Zhang W, Sun Z, Qi Z, Song L, Wei S. Single‐Atom‐Layer Catalysis in a MoS
2
Monolayer Activated by Long‐Range Ferromagnetism for the Hydrogen Evolution Reaction: Beyond Single‐Atom Catalysis. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202014968] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Hengli Duan
- National Synchrotron Radiation Laboratory University of Science and Technology of China 230029 Hefei Anhui China
| | - Chao Wang
- National Synchrotron Radiation Laboratory University of Science and Technology of China 230029 Hefei Anhui China
| | - Guinan Li
- National Synchrotron Radiation Laboratory University of Science and Technology of China 230029 Hefei Anhui China
| | - Hao Tan
- National Synchrotron Radiation Laboratory University of Science and Technology of China 230029 Hefei Anhui China
| | - Wei Hu
- National Synchrotron Radiation Laboratory University of Science and Technology of China 230029 Hefei Anhui China
| | - Liang Cai
- National Synchrotron Radiation Laboratory University of Science and Technology of China 230029 Hefei Anhui China
| | - Wei Liu
- National Synchrotron Radiation Laboratory University of Science and Technology of China 230029 Hefei Anhui China
| | - Na Li
- National Synchrotron Radiation Laboratory University of Science and Technology of China 230029 Hefei Anhui China
| | - Qianqian Ji
- National Synchrotron Radiation Laboratory University of Science and Technology of China 230029 Hefei Anhui China
| | - Yao Wang
- National Synchrotron Radiation Laboratory University of Science and Technology of China 230029 Hefei Anhui China
| | - Ying Lu
- National Synchrotron Radiation Laboratory University of Science and Technology of China 230029 Hefei Anhui China
| | - Wensheng Yan
- National Synchrotron Radiation Laboratory University of Science and Technology of China 230029 Hefei Anhui China
| | - Fengchun Hu
- National Synchrotron Radiation Laboratory University of Science and Technology of China 230029 Hefei Anhui China
| | - Wenhua Zhang
- National Synchrotron Radiation Laboratory University of Science and Technology of China 230029 Hefei Anhui China
| | - Zhihu Sun
- National Synchrotron Radiation Laboratory University of Science and Technology of China 230029 Hefei Anhui China
| | - Zeming Qi
- National Synchrotron Radiation Laboratory University of Science and Technology of China 230029 Hefei Anhui China
| | - Li Song
- National Synchrotron Radiation Laboratory University of Science and Technology of China 230029 Hefei Anhui China
| | - Shiqiang Wei
- National Synchrotron Radiation Laboratory University of Science and Technology of China 230029 Hefei Anhui China
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