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Qi J, Dai Y, Ma C, Ke C, Wang W, Wu Z, Wang X, Bao K, Xu Y, Huang H, Wang L, Wu J, Luo G, Chen Y, Lin Z, He Q. Surfactant-Free Ultrasonication-Assisted Synthesis of 2d Tellurium Based on Metastable 1T'-MoTe 2. Adv Mater 2024; 36:e2306962. [PMID: 37652747 DOI: 10.1002/adma.202306962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 08/21/2023] [Indexed: 09/02/2023]
Abstract
Elemental 2D materials (E2DMs) have been attracting considerable attention owing to their chemical simplicity and excellent/exotic properties. However, the lack of robust chemical synthetic methods seriously limits their potential. Here, a surfactant-free liquid-phase synthesis of high-quality 2D tellurium is reported based on ultrasonication-assisted exfoliation of metastable 1T'-MoTe2. The as-grown 2D tellurium nanosheets exhibit excellent single crystallinity, ideal 2D morphology, surfactant-free surface, and negligible 1D by-products. Furthermore, a unique growth mechanism based on the atomic escape of Te atoms from metastable transition metal dichalcogenides and guided 2D growth in the liquid phase is proposed and verified. 2D tellurium-based field-effect transistors show ultrahigh hole mobility exceeding 1000 cm2 V-1 s-1 at room temperature attributing to the high crystallinity and surfactant-free surface, and exceptional chemical and operational stability using both solid-state dielectric and liquid-state electrical double layer. The facile ultrasonication-assisted synthesis of high-quality 2D tellurium paves the way for further exploration of E2DMs and expands the scope of liquid-phase exfoliation (LPE) methodology toward the controlled wet-chemical synthesis of functional nanomaterials.
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Affiliation(s)
- Junlei Qi
- Department of Materials Science and Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong, 999077, China
| | - Yongping Dai
- Department of Chemistry, Engineering Research Center of Advanced Rare Earth Materials (Ministry of Education), Tsinghua University, Beijing, 100084, China
| | - Chen Ma
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, NT, Hong Kong, 999077, China
| | - Chengxuan Ke
- Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Wenbin Wang
- Department of Materials Science and Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong, 999077, China
| | - Zongxiao Wu
- Department of Materials Science and Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong, 999077, China
| | - Xiang Wang
- Department of Materials Science and Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong, 999077, China
| | - Kai Bao
- Department of Materials Science and Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong, 999077, China
| | - Yue Xu
- Department of Materials Science and Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong, 999077, China
| | - Haoxin Huang
- Department of Electrical Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong, 999077, China
| | - Lingzhi Wang
- Department of Materials Science and Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong, 999077, China
| | - Jingkun Wu
- Department of Materials Science and Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong, 999077, China
| | - Guangfu Luo
- Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Ye Chen
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, NT, Hong Kong, 999077, China
| | - Zhaoyang Lin
- Department of Chemistry, Engineering Research Center of Advanced Rare Earth Materials (Ministry of Education), Tsinghua University, Beijing, 100084, China
| | - Qiyuan He
- Department of Materials Science and Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong, 999077, China
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Dai B, Su Y, Guo Y, Wu C, Xie Y. Recent Strategies for the Synthesis of Phase-Pure Ultrathin 1T/1T' Transition Metal Dichalcogenide Nanosheets. Chem Rev 2024; 124:420-454. [PMID: 38146851 DOI: 10.1021/acs.chemrev.3c00422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2023]
Abstract
The past few decades have witnessed a notable increase in transition metal dichalcogenide (TMD) related research not only because of the large family of TMD candidates but also because of the various polytypes that arise from the monolayer configuration and layer stacking order. The peculiar physicochemical properties of TMD nanosheets enable an enormous range of applications from fundamental science to industrial technologies based on the preparation of high-quality TMDs. For polymorphic TMDs, the 1T/1T' phase is particularly intriguing because of the enriched density of states, and thus facilitates fruitful chemistry. Herein, we comprehensively discuss the most recent strategies for direct synthesis of phase-pure 1T/1T' TMD nanosheets such as mechanical exfoliation, chemical vapor deposition, wet chemical synthesis, atomic layer deposition, and more. We also review frequently adopted methods for phase engineering in TMD nanosheets ranging from chemical doping and alloying, to charge injection, and irradiation with optical or charged particle beams. Prior to the synthesis methods, we discuss the configuration of TMDs as well as the characterization tools mostly used in experiments. Finally, we discuss the current challenges and opportunities as well as emphasize the promising fields for the future development.
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Affiliation(s)
- Baohu Dai
- Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Yueqi Su
- Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Yuqiao Guo
- Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Changzheng Wu
- Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Yi Xie
- Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
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Cao C, Melegari M, Philippi M, Domaretskiy D, Ubrig N, Gutiérrez-Lezama I, Morpurgo AF. Full Control of Solid-State Electrolytes for Electrostatic Gating. Adv Mater 2023; 35:e2211993. [PMID: 36812653 DOI: 10.1002/adma.202211993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 02/10/2023] [Indexed: 05/05/2023]
Abstract
Ionic gating is a powerful technique to realize field-effect transistors (FETs) enabling experiments not possible otherwise. So far, ionic gating has relied on the use of top electrolyte gates, which pose experimental constraints and make device fabrication complex. Promising results obtained recently in FETs based on solid-state electrolytes remain plagued by spurious phenomena of unknown origin, preventing proper transistor operation, and causing limited control and reproducibility. Here, a class of solid-state electrolytes for gating (Lithium-ion conducting glass-ceramics, LICGCs) is explored, the processes responsible for the spurious phenomena and irreproducible behavior are identified, and properly functioning transistors exhibiting high density ambipolar operation with gate capacitance of ≈ 20 - 50 µ F c m - 2 \[20{\bm{ - }}50\;\mu F c{m^{{\bm{ - }}2}}\] (depending on the polarity of the accumulated charges) are demonstrated. Using 2D semiconducting transition-metal dichalcogenides, the ability to implement ionic-gate spectroscopy to determine the semiconducting bandgap, and to accumulate electron densities above 1014 cm-2 are demostrated, resulting in gate-induced superconductivity in MoS2 multilayers. As LICGCs are implemented in a back-gate configuration, they leave the surface of the material exposed, enabling the use of surface-sensitive techniques (such as scanning tunneling microscopy and photoemission spectroscopy) impossible so far in ionic-gated devices. They also allow double ionic gated devices providing independent control of charge density and electric field.
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Affiliation(s)
- Chuanwu Cao
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, Geneva, CH-1211, Switzerland
- Department of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, Geneva, CH-1211, Switzerland
| | - Margherita Melegari
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, Geneva, CH-1211, Switzerland
- Department of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, Geneva, CH-1211, Switzerland
| | - Marc Philippi
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, Geneva, CH-1211, Switzerland
- Department of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, Geneva, CH-1211, Switzerland
| | - Daniil Domaretskiy
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, Geneva, CH-1211, Switzerland
- Department of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, Geneva, CH-1211, Switzerland
| | - Nicolas Ubrig
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, Geneva, CH-1211, Switzerland
- Department of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, Geneva, CH-1211, Switzerland
| | - Ignacio Gutiérrez-Lezama
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, Geneva, CH-1211, Switzerland
- Department of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, Geneva, CH-1211, Switzerland
| | - Alberto F Morpurgo
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, Geneva, CH-1211, Switzerland
- Department of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, Geneva, CH-1211, Switzerland
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4
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Yang S, Chen W, Sa B, Guo Z, Zheng J, Pei J, Zhan H. Strain-Dependent Band Splitting and Spin-Flip Dynamics in Monolayer WS 2. Nano Lett 2023; 23:3070-3077. [PMID: 36995751 DOI: 10.1021/acs.nanolett.3c00771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Triggered by the expanding demands of semiconductor devices, strain engineering of two-dimensional transition metal dichalcogenides (TMDs) has garnered considerable research interest. Through steady-state measurements, strain has been proved in terms of its modulation of electronic energy bands and optoelectronic properties in TMDs. However, the influence of strain on the spin-orbit coupling as well as its related valley excitonic dynamics remains elusive. Here, we demonstrate the effect of strain on the excitonic dynamics of monolayer WS2 via steady-state fluorescence and transient absorption spectroscopy. Combined with theoretical calculations, we found that tensile strain can reduce the spin-splitting value of the conduction band and lead to transitions between different exciton states via spin-flip mechanism. Our findings suggest that the spin-flip process is strain-dependent, provides a reference for application of valleytronic devices, where tensile strain is usually existing during their design and fabrication.
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Affiliation(s)
- Shichao Yang
- College of Materials Science and Engineering, Fuzhou University, Fuzhou 350108, China
| | - Wenwei Chen
- College of Materials Science and Engineering, Fuzhou University, Fuzhou 350108, China
| | - Baisheng Sa
- College of Materials Science and Engineering, Fuzhou University, Fuzhou 350108, China
| | - Zhiyong Guo
- College of Materials Science and Engineering, Fuzhou University, Fuzhou 350108, China
| | - Jingying Zheng
- College of Materials Science and Engineering, Fuzhou University, Fuzhou 350108, China
| | - Jiajie Pei
- College of Materials Science and Engineering, Fuzhou University, Fuzhou 350108, China
| | - Hongbing Zhan
- College of Materials Science and Engineering, Fuzhou University, Fuzhou 350108, China
- Fujian Science & Technology Innovatation Laboratory for Optoelectronic Information, Fuzhou 350108, Fujian, Peoples Republic of China
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5
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Abstract
Electronic properties of two-dimensional (2D) materials can be significantly tuned by an external electric field. Ferroelectric gates can provide a strong polarization electric field. Here, we report the measurements of the band structure of few-layer MoS2 modulated by a ferroelectric P(VDF-TrFE) gate with contact-mode scanning tunneling spectroscopy. When P(VDF-TrFE) is fully polarized, an electric field up to ∼0.62 V/nm through the MoS2 layers is inferred from the measured band edges, which affects the band structure significantly. First, strong band bending in the vertical direction signifies the Franz-Keldysh effect and a large extension of the optical absorption edge. Photons with energy of half the band gap are still absorbed with 20% of the absorption probability of photons at the band gap. Second, the electric field greatly enlarges the energy separations between the quantum-well subbands. Our study intuitively demonstrates the great potential of ferroelectric gates in band structure manipulation of 2D materials.
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Affiliation(s)
- Xinzuo Sun
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yan Chen
- Shanghai Frontiers Science Research Base of Intelligent Optoelectronics and Perception, Institute of Optoelectronics, Fudan University, Shanghai 200433, China
- Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 20083, China
| | - Dongyang Zhao
- Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 20083, China
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Jianlu Wang
- Shanghai Frontiers Science Research Base of Intelligent Optoelectronics and Perception, Institute of Optoelectronics, Fudan University, Shanghai 200433, China
- Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 20083, China
- Frontier Institute of Chip and System, Fudan University, Shanghai 200433, China
| | - Jiamin Xue
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
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6
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Kausar A. Nanoporous graphene in polymeric nanocomposite membranes for gas separation and water purification—standings and headways. Journal of Macromolecular Science, Part A 2023. [DOI: 10.1080/10601325.2023.2177170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Affiliation(s)
- Ayesha Kausar
- NPU-NCP Joint International Research Center on Advanced Nanomaterials and Defects Engineering, National Centre for Physics, Islamabad, Pakistan
- NPU-NCP Joint International Research Center on Advanced Nanomaterials and Defects Engineering, Northwestern Polytechnical University, Xi’an, China
- UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, iThemba LABS, Somerset West, South Africa
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7
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Wang W, Song Y, Ke C, Li Y, Liu Y, Ma C, Wu Z, Qi J, Bao K, Wang L, Wu J, Jiang S, Zhao J, Lee CS, Chen Y, Luo G, He Q, Ye R. Filling the Gap between Heteroatom Doping and Edge Enrichment of 2D Electrocatalysts for Enhanced Hydrogen Evolution. ACS Nano 2023; 17:1287-1297. [PMID: 36629409 DOI: 10.1021/acsnano.2c09423] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Composition modulation and edge enrichment are established protocols to steer the electronic structures and catalytic activities of two-dimensional (2D) materials. It is believed that a heteroatom enhances the catalytic performance by activating the chemically inert basal plane of 2D crystals. However, the edge and basal plane have inherently different electronic states, and how the dopants affect the edge activity remains ambiguous. Here we provide mechanistic insights into this issue by monitoring the hydrogen evolution reaction (HER) performance of phosphorus-doped MoS2 (P-MoS2) nanosheets via on-chip electrocatalytic microdevices. Upon phosphorus doping, MoS2 nanosheet gets catalytically activated and, more importantly, shows higher HER activity in the edge than the basal plane. In situ transport measurement demonstrates that the improved HER performance of P-MoS2 is derived from intrinsic catalytic activity rather than charge transfer. Density functional theory calculations manifest that the edge sites of P-MoS2 are energetically more favorable for HER. The finding guides the rational design of edge-dominant P-MoS2, reaching a minuscule onset potential of ∼30 mV and Tafel slope of 48 mV/dec that are benchmarked against other activation methods. Our results disclose the hitherto overlooked edge activity of 2D materials induced by heteroatom doping that will provide perspectives for preparing next-generation 2D catalysts.
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Affiliation(s)
- Wenbin Wang
- City University of Hong Kong Shenzhen Research Institute, Shenzhen, Guangdong518057, China
- Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong, China
| | - Yun Song
- Department of Chemistry and State Key Laboratory of Marine Pollution, City University of Hong Kong, Kowloon, Hong Kong, China
| | - Chengxuan Ke
- Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong, China
- Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong518055, China
| | - Yang Li
- Department of Chemistry and State Key Laboratory of Marine Pollution, City University of Hong Kong, Kowloon, Hong Kong, China
| | - Yong Liu
- Department of Chemistry and State Key Laboratory of Marine Pollution, City University of Hong Kong, Kowloon, Hong Kong, China
| | - Chen Ma
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Zongxiao Wu
- Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong, China
| | - Junlei Qi
- Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong, China
| | - Kai Bao
- Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong, China
| | - Lingzhi Wang
- Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong, China
| | - Jingkun Wu
- Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong, China
| | - Shan Jiang
- Department of Applied Physics, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China
| | - Jiong Zhao
- Department of Applied Physics, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China
| | - Chun-Sing Lee
- Department of Chemistry and State Key Laboratory of Marine Pollution, City University of Hong Kong, Kowloon, Hong Kong, China
- Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Kowloon, Hong Kong, China
| | - Ye Chen
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Guangfu Luo
- Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong518055, China
- Guangdong Provincial Key Laboratory of Computational Science and Material Design, Southern University of Science and Technology, Shenzhen, Guangdong518055, China
| | - Qiyuan He
- Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong, China
| | - Ruquan Ye
- City University of Hong Kong Shenzhen Research Institute, Shenzhen, Guangdong518057, China
- Department of Chemistry and State Key Laboratory of Marine Pollution, City University of Hong Kong, Kowloon, Hong Kong, China
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Zeng L, Zhang S, Yao L, Bi Z, Zhang Y, Kang P, Yan J, Zhang Z, Yun J. A type-II NGyne/GaSe heterostructure with high carrier mobility and tunable electronic properties for photovoltaic application. Nanotechnology 2022; 34:065702. [PMID: 36356303 DOI: 10.1088/1361-6528/aca1cc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 11/10/2022] [Indexed: 06/16/2023]
Abstract
The two-dimensional heterostructures with type-II band alignment and super-high carrier mobility offer an updated perspective for photovoltaic devices. Here, based on the first-principles calculation, a novel vertical NGyne/GaSe heterostructure with an intrinsic type-II band alignment, super-high carrier mobility (104cm2V-1s-1), and strong visible to ultraviolet light absorption (104-105cm-1) is constructed. We investigate the electronic structure and the interfacial properties of the NGyne/GaSe heterostructure under electric field and strain. The band offsets and band gap of the NGyne/GaSe heterostructure can be regulated under applied vertical electric field and strain efficiently. Further study reveals that the photoelectric conversion efficiency of the NGyne/GaSe heterostructure is vastly improved under a negative electric field and reaches up to 25.09%. Meanwhile, near-free electron states are induced under a large applied electric field, leading to the NGyne/GaSe heterostructure transform from semiconductors to metal. Our results indicate that the NGyne/GaSe heterostructure will have extremely potential in optoelectronic devices, especially solar cells.
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Affiliation(s)
- Liru Zeng
- School of Information Science and Technology, Northwest University, Xi'an, 710127, People's Republic of China
| | - Siyu Zhang
- School of Information Science and Technology, Northwest University, Xi'an, 710127, People's Republic of China
| | - Linwei Yao
- School of Information Science and Technology, Northwest University, Xi'an, 710127, People's Republic of China
| | - Zhisong Bi
- School of Information Science and Technology, Northwest University, Xi'an, 710127, People's Republic of China
| | - Yanni Zhang
- College of Physics & Electronic Engineering, Xianyang Normal University, Xianyang, 712000, People's Republic of China
| | - Peng Kang
- Department of Physics, McGill University, Montreal, Quebec H3A 2T8, Canada
| | - Junfeng Yan
- School of Information Science and Technology, Northwest University, Xi'an, 710127, People's Republic of China
| | - Zhiyong Zhang
- School of Information Science and Technology, Northwest University, Xi'an, 710127, People's Republic of China
| | - Jiangni Yun
- School of Information Science and Technology, Northwest University, Xi'an, 710127, People's Republic of China
- Department of Physics, McGill University, Montreal, Quebec H3A 2T8, Canada
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9
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Weintrub BI, Hsieh YL, Kovalchuk S, Kirchhof JN, Greben K, Bolotin KI. Generating intense electric fields in 2D materials by dual ionic gating. Nat Commun 2022; 13:6601. [PMID: 36329011 DOI: 10.1038/s41467-022-34158-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 10/14/2022] [Indexed: 11/06/2022] Open
Abstract
The application of an electric field through two-dimensional materials (2DMs) modifies their properties. For example, a bandgap opens in semimetallic bilayer graphene while the bandgap shrinks in few-layer 2D semiconductors. The maximum electric field strength achievable in conventional devices is limited to ≤0.3 V/nm by the dielectric breakdown of gate dielectrics. Here, we overcome this limit by suspending a 2DM between two volumes of ionic liquid (IL) with independently controlled potentials. The potential difference between the ILs falls across an ultrathin layer consisting of the 2DM and the electrical double layers above and below it, producing an intense electric field larger than 4 V/nm. This field is strong enough to close the bandgap of few-layer WSe2, thereby driving a semiconductor-to-metal transition. The ability to apply fields an order of magnitude higher than what is possible in dielectric-gated devices grants access to previously-inaccessible phenomena occurring in intense electric fields. The application of electric fields >1 V/nm in solid state devices could provide access to unexplored phenomena, but it is currently difficult to implement. Here, the authors develop a double-sided ionic liquid gating technique to generate electric fields as large as 4 V/nm across few-layer WSe2, leading to field-induced semiconductor-to-metal transitions.
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Knobloch T, Selberherr S, Grasser T. Challenges for Nanoscale CMOS Logic Based on Two-Dimensional Materials. Nanomaterials (Basel) 2022; 12:nano12203548. [PMID: 36296740 PMCID: PMC9609734 DOI: 10.3390/nano12203548] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 09/30/2022] [Accepted: 10/03/2022] [Indexed: 06/02/2023]
Abstract
For ultra-scaled technology nodes at channel lengths below 12 nm, two-dimensional (2D) materials are a potential replacement for silicon since even atomically thin 2D semiconductors can maintain sizable mobilities and provide enhanced gate control in a stacked channel nanosheet transistor geometry. While theoretical projections and available experimental prototypes indicate great potential for 2D field effect transistors (FETs), several major challenges must be solved to realize CMOS logic circuits based on 2D materials at the wafer scale. This review discusses the most critical issues and benchmarks against the targets outlined for the 0.7 nm node in the International Roadmap for Devices and Systems scheduled for 2034. These issues are grouped into four areas; device scaling, the formation of low-resistive contacts to 2D semiconductors, gate stack design, and wafer-scale process integration. Here, we summarize recent developments in these areas and identify the most important future research questions which will have to be solved to allow for industrial adaptation of the 2D technology.
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