1
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Vashishtha P, Abidi IH, Giridhar SP, Verma AK, Prajapat P, Bhoriya A, Murdoch BJ, Tollerud JO, Xu C, Davis JA, Gupta G, Walia S. CVD-Grown Monolayer MoS 2 and GaN Thin Film Heterostructure for a Self-Powered and Bidirectional Photodetector with an Extended Active Spectrum. ACS APPLIED MATERIALS & INTERFACES 2024; 16:31294-31303. [PMID: 38838350 DOI: 10.1021/acsami.4c03902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2024]
Abstract
Photodetector technology has evolved significantly over the years with the emergence of new active materials. However, there remain trade-offs between spectral sensitivity, operating energy, and, more recently, an ability to harbor additional features such as persistent photoconductivity and bidirectional photocurrents for new emerging application areas such as switchable light imaging and filter-less color discrimination. Here, we demonstrate a self-powered bidirectional photodetector based on molybdenum disulfide/gallium nitride (MoS2/GaN) epitaxial heterostructure. This fabricated detector exhibits self-powered functionality and achieves detection in two discrete wavelength bands: ultraviolet and visible. Notably, it attains a peak responsivity of 631 mAW-1 at a bias of 0V. The device's response to illumination at these two wavelengths is governed by distinct mechanisms, activated under applied bias conditions, thereby inducing a reversal in the polarity of the photocurrent. This work underscores the feasibility of self-powered and bidirectional photocurrent detection but also opens new vistas for technological advancements for future optoelectronic, neuromorphic, and sensing applications.
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Affiliation(s)
- Pargam Vashishtha
- School of Engineering, RMIT University, Melbourne, Victoria 3000, Australia
- Academy of Scientific and Innovative Research, CSIR-HRDC Campus, Ghaziabad 201002, Uttar Pradesh, India
- CSIR-National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012, India
| | - Irfan H Abidi
- School of Engineering, RMIT University, Melbourne, Victoria 3000, Australia
| | - Sindhu P Giridhar
- School of Engineering, RMIT University, Melbourne, Victoria 3000, Australia
| | - Ajay K Verma
- School of Engineering, RMIT University, Melbourne, Victoria 3000, Australia
- Academy of Scientific and Innovative Research, CSIR-HRDC Campus, Ghaziabad 201002, Uttar Pradesh, India
- CSIR-National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012, India
| | - Pukhraj Prajapat
- Academy of Scientific and Innovative Research, CSIR-HRDC Campus, Ghaziabad 201002, Uttar Pradesh, India
- CSIR-National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012, India
| | - Ankit Bhoriya
- School of Engineering, RMIT University, Melbourne, Victoria 3000, Australia
- Academy of Scientific and Innovative Research, CSIR-HRDC Campus, Ghaziabad 201002, Uttar Pradesh, India
- CSIR-National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012, India
| | - Billy J Murdoch
- RMIT Microscopy and Microanalysis Facility, RMIT University, Melbourne 3000, Australia
| | - Jonathan O Tollerud
- Optical Sciences Centre, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia
| | - Chenglong Xu
- Micro Nano Research Facility, RMIT University, Melbourne 3000, Australia
| | - Jeff A Davis
- Optical Sciences Centre, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia
| | - Govind Gupta
- Academy of Scientific and Innovative Research, CSIR-HRDC Campus, Ghaziabad 201002, Uttar Pradesh, India
- CSIR-National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012, India
| | - Sumeet Walia
- School of Engineering, RMIT University, Melbourne, Victoria 3000, Australia
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2
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Yao YC, Wu BY, Chin HT, Yen ZL, Ting CC, Hofmann M, Hsieh YP. Nitrogen Pretreatment of Growth Substrates for Vacancy-Saturated MoS 2. ACS APPLIED MATERIALS & INTERFACES 2023; 15:42746-42752. [PMID: 37646637 DOI: 10.1021/acsami.3c07793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
Two-dimensional transition-metal dichalcogenides (2D TMDCs) are considered promising materials for optoelectronics due to their unique optical and electric properties. However, their potential has been limited by the occurrence of atomic vacancies during synthesis. While post-treatment processes have demonstrated the passivation of such vacancies, they increase process complexity and affect the TMDC's quality. We here introduce the concept of pretreatment as a facile and powerful route to solve the problem of vacancies in MoS2. Low-temperature nitridation of the sapphire substrate prior to growth provides a nondestructive method to MoS2 modification without introducing new processing steps or increasing the thermal budget. Spectroscopic characterization and atomic-resolution microscopy reveal the incorporation of nitrogen from the sapphire surface layer into chalcogen vacancies. The resulting MoS2 with nitrogen-saturated defects shows a decrease in midgap states and more intrinsic doping as confirmed by ab initio calculations and optoelectronic measurements. The demonstrated pretreatment method opens up new routes toward future, high-performance 2D electronics, as evidenced by a 3-fold reduction in contact resistance and a 10-fold improved performance of 2D photodetectors.
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Affiliation(s)
- Yu-Chi Yao
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - Bo-Yi Wu
- Graduate Institute of Opto-Mechatronics, Department of Mechanical Engineering, National Chung Cheng University, Chia-Yi 62102, Taiwan
| | - Hao-Ting Chin
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
- International Graduate Program of Molecular Science and Technology, National Taiwan University, Taipei 10617, Taiwan
- Molecular Science and Technology Program, Taiwan International Graduate Program, Academia Sinica, Taipei 10617, Taiwan
| | - Zhi-Long Yen
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
- International Graduate Program of Molecular Science and Technology, National Taiwan University, Taipei 10617, Taiwan
- Molecular Science and Technology Program, Taiwan International Graduate Program, Academia Sinica, Taipei 10617, Taiwan
| | - Chu-Chi Ting
- Graduate Institute of Opto-Mechatronics, Department of Mechanical Engineering, National Chung Cheng University, Chia-Yi 62102, Taiwan
| | - Mario Hofmann
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - Ya-Ping Hsieh
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
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3
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Zhu Y, Lim J, Zhang Z, Wang Y, Sarkar S, Ramsden H, Li Y, Yan H, Phuyal D, Gauriot N, Rao A, Hoye RLZ, Eda G, Chhowalla M. Room-Temperature Photoluminescence Mediated by Sulfur Vacancies in 2D Molybdenum Disulfide. ACS NANO 2023. [PMID: 37418552 PMCID: PMC10373523 DOI: 10.1021/acsnano.3c02103] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/09/2023]
Abstract
Atomic defects in monolayer transition metal dichalcogenides (TMDs) such as chalcogen vacancies significantly affect their properties. In this work, we provide a reproducible and facile strategy to rationally induce chalcogen vacancies in monolayer MoS2 by annealing at 600 °C in an argon/hydrogen (95%/5%) atmosphere. Synchrotron X-ray photoelectron spectroscopy shows that a Mo 3d5/2 core peak at 230.1 eV emerges in the annealed MoS2 associated with nonstoichiometric MoSx (0 < x < 2), and Raman spectroscopy shows an enhancement of the ∼380 cm-1 peak that is attributed to sulfur vacancies. At sulfur vacancy densities of ∼1.8 × 1014 cm-2, we observe a defect peak at ∼1.72 eV (referred to as LXD) at room temperature in the photoluminescence (PL) spectrum. The LXD peak is attributed to excitons trapped at defect-induced in-gap states and is typically observed only at low temperatures (≤77 K). Time-resolved PL measurements reveal that the lifetime of defect-mediated LXD emission is longer than that of band edge excitons, both at room and low temperatures (∼2.44 ns at 8 K). The LXD peak can be suppressed by annealing the defective MoS2 in sulfur vapor, which indicates that it is possible to passivate the vacancies. Our results provide insights into how excitonic and defect-mediated PL emissions in MoS2 are influenced by sulfur vacancies at room and low temperatures.
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Affiliation(s)
- Yiru Zhu
- Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - Juhwan Lim
- Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
- Cavendish Laboratory, University of Cambridge, Cambridge CB2 1TN, United Kingdom
| | - Zhepeng Zhang
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117551, Singapore
| | - Yan Wang
- Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - Soumya Sarkar
- Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - Hugh Ramsden
- Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - Yang Li
- Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - Han Yan
- Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - Dibya Phuyal
- Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
- Division of Material and Nano Physics, Department of Applied Physics, KTH Royal Institute of Technology, Stockholm, SE-106 91, Sweden
| | - Nicolas Gauriot
- Cavendish Laboratory, University of Cambridge, Cambridge CB2 1TN, United Kingdom
| | - Akshay Rao
- Cavendish Laboratory, University of Cambridge, Cambridge CB2 1TN, United Kingdom
| | - Robert L Z Hoye
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
| | - Goki Eda
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117551, Singapore
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore
- Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, 117542, Singapore
| | - Manish Chhowalla
- Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
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4
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Martín-Roca J, Horcajo-Fernández M, Valeriani C, Gámez F, Martínez-Pedrero F. Field-Pulse-Induced Annealing of 2D Colloidal Polycrystals. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:397. [PMID: 36770358 PMCID: PMC9921439 DOI: 10.3390/nano13030397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 01/13/2023] [Accepted: 01/16/2023] [Indexed: 06/18/2023]
Abstract
Two-dimensional colloidal crystals are of considerable fundamental and practical importance. However, their quality is often low due to the widespread presence of domain walls and defects. In this work, we explored the annealing process undergone by monolayers of superparamagnetic colloids adsorbed onto fluid interfaces in the presence of magnetic field pulses. These systems present the extraordinary peculiarity that both the extent and the character of interparticle interactions can be adjusted at will by simply varying the strength and orientation of the applied field so that the application of field pulses results in a sudden input of energy. Specifically, we have studied the effect of polycrystal size, pulse duration, slope and frequency on the efficiency of the annealing process and found that (i) this strategy is only effective when the polycrystal consists of less than approximately 10 domains; (ii) that the pulse duration should be of the order of magnitude of the time required for the outer particles to travel one diameter during the heating step; (iii) that the quality of larger polycrystals can be slightly improved by applying tilted pulses. The experimental results were corroborated by Brownian dynamics simulations.
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Affiliation(s)
- José Martín-Roca
- Departamento de Estructura de la Materia, Física Térmica y Electrónica, Universidad Complutense de Madrid, 28040 Madrid, Spain
- GISC-Grupo Interdisciplinar de Sistemas Complejos, 28040 Madrid, Spain
| | | | - Chantal Valeriani
- Departamento de Estructura de la Materia, Física Térmica y Electrónica, Universidad Complutense de Madrid, 28040 Madrid, Spain
- GISC-Grupo Interdisciplinar de Sistemas Complejos, 28040 Madrid, Spain
| | - Francisco Gámez
- Departamento de Química-Física, Universidad Complutense de Madrid, 28040 Madrid, Spain
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5
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Li S, Nishimura T, Maruyama M, Okada S, Nagashio K. Experimental verification of SO 2 and S desorption contributing to defect formation in MoS 2 by thermal desorption spectroscopy. NANOSCALE ADVANCES 2023; 5:405-411. [PMID: 36756254 PMCID: PMC9846482 DOI: 10.1039/d2na00636g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2022] [Accepted: 11/25/2022] [Indexed: 06/18/2023]
Abstract
The defect-free surface of MoS2 is of high importance for applications in electronic devices. Theoretical calculations have predicted that oxidative etching could be responsible for sulfur vacancy formation. No direct experimental evidence, however, points out the role of adsorbed oxygen on sulfur vacancy formation for MoS2, especially on an insulating SiO2/Si substrate. Herein, by applying thermal desorption spectroscopy, we found that sulfur loss can be tightly coupled to adsorbed oxygen, as confirmed by observation of SO2 desorption. With annealing MoS2, even under ultrahigh vacuum, oxygen molecules adsorbed on MoS2 assist the sulfur atom in dissociating from MoS2, and thus, defects are formed as the result of SO2 desorption from 200 °C to 600 °C. At higher temperatures (over 800 °C), on the other hand, direct sulfur desorption becomes dominant. This finding can be well explained by combining the morphology investigation enabled by atomic layer deposition at defective sites and optical transitions observed by photoluminescence measurements. Moreover, a preannealing treatment prior to exfoliation was found to be an effective method to remove the adsorbed oxygen, thus preventing defect formation.
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Affiliation(s)
- Shuhong Li
- Department of Materials Engineering, University of Tokyo Tokyo 113-8656 Japan
- Department of Physics, University of Tsukuba Tsukuba Ibaraki 305-8577 Japan
| | - Tomonori Nishimura
- Department of Materials Engineering, University of Tokyo Tokyo 113-8656 Japan
| | - Mina Maruyama
- Department of Physics, University of Tsukuba Tsukuba Ibaraki 305-8577 Japan
| | - Susumu Okada
- Department of Physics, University of Tsukuba Tsukuba Ibaraki 305-8577 Japan
| | - Kosuke Nagashio
- Department of Materials Engineering, University of Tokyo Tokyo 113-8656 Japan
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6
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Graphene nano-electromechanical mass sensor with high resolution at room temperature. iScience 2023; 26:105958. [PMID: 36718371 PMCID: PMC9883292 DOI: 10.1016/j.isci.2023.105958] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 12/26/2022] [Accepted: 01/08/2023] [Indexed: 01/15/2023] Open
Abstract
The inherent properties of 2D materials-light mass, high out-of-plane flexibility, and large surface area-promise great potential for precise and accurate nanomechanical mass sensing, but their application is often hampered by surface contamination. Here we demonstrate a tri-layer graphene nanomechanical resonant mass sensor with sub-attogram resolution at room temperature, fabricated by a bottom-up process. We found that Joule-heating is effective in cleaning the graphene membrane surface, which results in a large improvement in the stability of the resonance frequency. We characterized the sensor by depositing Cr metal using a stencil mask and found a mass-resolution that is sufficient to weigh very small particles, like large proteins and protein complexes, with potential applications in the fields of nanobiology and medicine.
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7
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Liu CJ, Wan Y, Li LJ, Lin CP, Hou TH, Huang ZY, Hu VPH. 2D Materials-Based Static Random-Access Memory. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2107894. [PMID: 34932857 DOI: 10.1002/adma.202107894] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Revised: 12/14/2021] [Indexed: 06/14/2023]
Abstract
2D transition-metal dichalcogenide semiconductors, such as MoS2 and WSe2 , with adequate bandgaps are promising channel materials for ultrascaled logic transistors. This scalability study of 2D material (2DM)-based field-effect transistor (FET) and static random-access memory (SRAM) cells analyzing the impact of layer thickness reveals that the monolayer 2DM FET with superior electrostatics is beneficial for its ability to mitigate the read-write conflict in an SRAM cell at scaled technology nodes (1-2.1 nm). Moreover, the monolayer 2DM SRAM exhibits lower cell read access time and write time than the bilayer and trilayer 2DM SRAM cells at fixed leakage power. This simulation predicts that the optimization of 2DM SRAM designed with state-of-the-art contact resistance, mobility, and equivalent oxide thickness leads to excellent stability and operation speed at the 1-nm node. Applying the nanosheet (NS) gate-all-around (GAA) structure to 2DM further reduces cell read access time and write time and improves the area density of the SRAM cells, demonstrating a feasible scaling path beyond Si technology using 2DM NSFETs. In addition to the device design, the process challenges for 2DM NSFETs, including the cost-effective stacking of 2DM layers, formation of electrical contacts, suspended 2DM channels, and GAA structures, are also discussed.
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Affiliation(s)
- Chang-Ju Liu
- Department of Electrical Engineering, National Central University, Taoyuan, 320, Taiwan
| | - Yi Wan
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, 9999077, Hong Kong
| | - Lain-Jong Li
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, 9999077, Hong Kong
| | - Chih-Pin Lin
- Department of Electrical Engineering and Institute of Electronics, National Yang Ming Chiao Tung University, Hsinchu, 300, Taiwan
| | - Tuo-Hung Hou
- Department of Electrical Engineering and Institute of Electronics, National Yang Ming Chiao Tung University, Hsinchu, 300, Taiwan
| | - Zi-Yuan Huang
- Department of Electrical Engineering and Graduate Institute of Electronics Engineering, National Taiwan University, Taipei, 106, Taiwan
| | - Vita Pi-Ho Hu
- Department of Electrical Engineering and Graduate Institute of Electronics Engineering, National Taiwan University, Taipei, 106, Taiwan
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8
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Wang X, Wu J, Zhang Y, Sun Y, Ma K, Xie Y, Zheng W, Tian Z, Kang Z, Zhang Y. Vacancy Defects in 2D Transition Metal Dichalcogenide Electrocatalysts: From Aggregated to Atomic Configuration. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022:e2206576. [PMID: 36189862 DOI: 10.1002/adma.202206576] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 09/15/2022] [Indexed: 06/16/2023]
Abstract
Vacancy defect engineering has been well leveraged to flexibly shape comprehensive physicochemical properties of diverse catalysts. In particular, growing research effort has been devoted to engineering chalcogen anionic vacancies (S/Se/Te) of 2D transition metal dichalcogenides (2D TMDs) toward the ultimate performance limit of electrocatalytic hydrogen evolution reaction (HER). In spite of remarkable progress achieved in the past decade, systematic and in-depth insights into the state-of-the-art vacancy engineering for 2D-TMDs-based electrocatalysis are still lacking. Herein, this review delivers a full picture of vacancy engineering evolving from aggregated to atomic configurations covering their development background, controllable manufacturing, thorough characterization, and representative HER application. Of particular interest, the deep-seated correlations between specific vacancy regulation routes and resulting catalytic performance improvement are logically clarified in terms of atomic rearrangement, charge redistribution, energy band variation, intermediate adsorption-desorption optimization, and charge/mass transfer facilitation. Beyond that, a broader vision is cast into the cutting-edge research fields of vacancy-engineering-based single-atom catalysis and dynamic structure-performance correlations across catalyst service lifetime. Together with critical discussion on residual challenges and future prospects, this review sheds new light on the rational design of advanced defect catalysts and navigates their broader application in high-efficiency energy conversion and storage fields.
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Affiliation(s)
- Xin Wang
- Academy for Advanced Interdisciplinary Science and Technology, Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Jing Wu
- Academy for Advanced Interdisciplinary Science and Technology, Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Yuwei Zhang
- Academy for Advanced Interdisciplinary Science and Technology, Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Yu Sun
- Academy for Advanced Interdisciplinary Science and Technology, Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Kaikai Ma
- Academy for Advanced Interdisciplinary Science and Technology, Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Yong Xie
- Academy for Advanced Interdisciplinary Science and Technology, Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Wenhao Zheng
- Academy for Advanced Interdisciplinary Science and Technology, Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Zhen Tian
- Academy for Advanced Interdisciplinary Science and Technology, Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Zhuo Kang
- Academy for Advanced Interdisciplinary Science and Technology, Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Yue Zhang
- Academy for Advanced Interdisciplinary Science and Technology, Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
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9
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Cao J, Yin W, Zhang Q, Yao Y, Cao J, Wei X. Intrinsic anion vacancy of Mo6X6 (X = S, Se, Te) nanowires as a promising nitrogen fixation catalysis: A first-principles study. Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2022.139752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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10
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Zhou J, Zhang C, Shi L, Chen X, Kim TS, Gyeon M, Chen J, Wang J, Yu L, Wang X, Kang K, Orgiu E, Samorì P, Watanabe K, Taniguchi T, Tsukagoshi K, Wang P, Shi Y, Li S. Non-invasive digital etching of van der Waals semiconductors. Nat Commun 2022; 13:1844. [PMID: 35383178 PMCID: PMC8983769 DOI: 10.1038/s41467-022-29447-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 03/14/2022] [Indexed: 11/12/2022] Open
Abstract
The capability to finely tailor material thickness with simultaneous atomic precision and non-invasivity would be useful for constructing quantum platforms and post-Moore microelectronics. However, it remains challenging to attain synchronized controls over tailoring selectivity and precision. Here we report a protocol that allows for non-invasive and atomically digital etching of van der Waals transition-metal dichalcogenides through selective alloying via low-temperature thermal diffusion and subsequent wet etching. The mechanism of selective alloying between sacrifice metal atoms and defective or pristine dichalcogenides is analyzed with high-resolution scanning transmission electron microscopy. Also, the non-invasive nature and atomic level precision of our etching technique are corroborated by consistent spectral, crystallographic, and electrical characterization measurements. The low-temperature charge mobility of as-etched MoS2 reaches up to 1200 cm2 V−1s−1, comparable to that of exfoliated pristine counterparts. The entire protocol represents a highly precise and non-invasive tailoring route for material manipulation. Here, the authors exploit a non-invasive layer-bylayer etching technique to fabricate electronic devices based on 2D transition metal dichalcogenides with controlled thickness and transport properties comparable to those of exfoliated flakes.
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Affiliation(s)
- Jian Zhou
- National Laboratory of Solid-State Microstructures and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China.,School of Electronic Science and Engineering, Nanjing University, Nanjing, China
| | - Chunchen Zhang
- National Laboratory of Solid-State Microstructures and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China.,College of Engineering and Applied Sciences and Jiangsu Key Laboratory of Artificial Functional Materials, Nanjing University, Nanjing, China
| | - Li Shi
- Department of Physics, Southeast University, Nanjing, China
| | - Xiaoqing Chen
- National Laboratory of Solid-State Microstructures and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China.,School of Electronic Science and Engineering, Nanjing University, Nanjing, China
| | - Tae Soo Kim
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
| | - Minseung Gyeon
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
| | - Jian Chen
- National Laboratory of Solid-State Microstructures and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China.,School of Electronic Science and Engineering, Nanjing University, Nanjing, China
| | - Jinlan Wang
- Department of Physics, Southeast University, Nanjing, China
| | - Linwei Yu
- National Laboratory of Solid-State Microstructures and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China.,School of Electronic Science and Engineering, Nanjing University, Nanjing, China
| | - Xinran Wang
- National Laboratory of Solid-State Microstructures and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China.,School of Electronic Science and Engineering, Nanjing University, Nanjing, China
| | - Kibum Kang
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
| | - Emanuele Orgiu
- Institut national de la recherche scientifique, Centre Énergie Matériaux Télécommunications, 1650 Blvd. Lionel-Boulet, J3X 1S2, Varennes, QC, Canada
| | - Paolo Samorì
- University of Strasbourg, CNRS, ISIS UMR 7006, 8 allée Gaspard Monge, F-67000, Strasbourg, France.
| | - Kenji Watanabe
- WPI-MANA, National Institute for Materials Science, Tsukuba, 305-0044, Ibaraki, Japan
| | - Takashi Taniguchi
- WPI-MANA, National Institute for Materials Science, Tsukuba, 305-0044, Ibaraki, Japan
| | - Kazuhito Tsukagoshi
- WPI-MANA, National Institute for Materials Science, Tsukuba, 305-0044, Ibaraki, Japan
| | - Peng Wang
- National Laboratory of Solid-State Microstructures and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China. .,College of Engineering and Applied Sciences and Jiangsu Key Laboratory of Artificial Functional Materials, Nanjing University, Nanjing, China. .,Department of Physics, University of Warwick, CV4 7AL, Coventry, UK.
| | - Yi Shi
- National Laboratory of Solid-State Microstructures and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China. .,School of Electronic Science and Engineering, Nanjing University, Nanjing, China.
| | - Songlin Li
- National Laboratory of Solid-State Microstructures and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China. .,School of Electronic Science and Engineering, Nanjing University, Nanjing, China.
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11
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Rahman R, Karmakar M, Samanta D, Pathak A, Datta PK, Nath TK. One order enhancement of charge carrier relaxation rate by tuning structural and optical properties in annealed cobalt doped MoS 2 nanosheets. NEW J CHEM 2022. [DOI: 10.1039/d1nj05446e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The effective manipulation of excitons is crucial for the realization of exciton-based devices and circuits, and doping is considered a good strategy to achieve this.
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Affiliation(s)
- Rosy Rahman
- Department of Physics, Indian Institute of Technology Kharagpur, W.B., 721302, India
| | - Manobina Karmakar
- Department of Physics, Indian Institute of Technology Kharagpur, W.B., 721302, India
| | - Dipanjan Samanta
- Department of Chemistry, Indian Institute of Technology Kharagpur, W.B., 721302, India
| | - Amita Pathak
- Department of Chemistry, Indian Institute of Technology Kharagpur, W.B., 721302, India
| | - Prasanta Kumar Datta
- Department of Physics, Indian Institute of Technology Kharagpur, W.B., 721302, India
| | - Tapan Kumar Nath
- Department of Physics, Indian Institute of Technology Kharagpur, W.B., 721302, India
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12
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Wu Z, Wang J, Li H, Cao L, Dong B. Boosting of Oxygen Evolution Reaction Performance through Defect and Lattice Distortion Engineering. NEW J CHEM 2022. [DOI: 10.1039/d2nj00104g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Developing efficient, stable, and inexpensive electrocatalyst for oxygen evolution reaction (OER) is significant for development and utilization of clean energy. Defects in electrocatalysts strongly impact their chemical properties and can...
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13
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Wang X, Zhang Y, Wu J, Zhang Z, Liao Q, Kang Z, Zhang Y. Single-Atom Engineering to Ignite 2D Transition Metal Dichalcogenide Based Catalysis: Fundamentals, Progress, and Beyond. Chem Rev 2021; 122:1273-1348. [PMID: 34788542 DOI: 10.1021/acs.chemrev.1c00505] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Single-atom catalysis has been recognized as a pivotal milestone in the development history of heterogeneous catalysis by virtue of its superior catalytic performance, ultrahigh atomic utilization, and well-defined structure. Beyond single-atom protrusions, two more motifs of single-atom substitutions and single-atom vacancies along with synergistic single-atom motif assemblies have been progressively developed to enrich the single-atom family. On the other hand, besides traditional carbon material based substrates, a wide variety of 2D transitional metal dichalcogenides (TMDs) have been emerging as a promising platform for single-atom catalysis owing to their diverse elemental compositions, variable crystal structures, flexible electronic structures, and intrinsic activities toward many catalytic reactions. Such substantial expansion of both single-atom motifs and substrates provides an enriched toolbox to further optimize the geometric and electronic structures for pushing the performance limit. Concomitantly, higher requirements have been put forward for synthetic and characterization techniques with related technical bottlenecks being continuously conquered. Furthermore, this burgeoning single-atom catalyst (SAC) system has triggered serial scientific issues about their changeable single atom-2D substrate interaction, ambiguous synergistic effects of various atomic assemblies, as well as dynamic structure-performance correlations, all of which necessitate further clarification and comprehensive summary. In this context, this Review aims to summarize and critically discuss the single-atom engineering development in the whole field of 2D TMD based catalysis covering their evolution history, synthetic methodologies, characterization techniques, catalytic applications, and dynamic structure-performance correlations. In situ characterization techniques are highlighted regarding their critical roles in real-time detection of SAC reconstruction and reaction pathway evolution, thus shedding light on lifetime dynamic structure-performance correlations which lay a solid theoretical foundation for the whole catalytic field, especially for SACs.
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Affiliation(s)
- Xin Wang
- Academy for Advanced Interdisciplinary Science and Technology, Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing 100083, P. R. China.,State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, P. R. China
| | - Yuwei Zhang
- Academy for Advanced Interdisciplinary Science and Technology, Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing 100083, P. R. China.,State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, P. R. China
| | - Jing Wu
- Academy for Advanced Interdisciplinary Science and Technology, Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing 100083, P. R. China.,State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, P. R. China
| | - Zheng Zhang
- Academy for Advanced Interdisciplinary Science and Technology, Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing 100083, P. R. China.,State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, P. R. China
| | - Qingliang Liao
- Academy for Advanced Interdisciplinary Science and Technology, Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing 100083, P. R. China.,State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, P. R. China
| | - Zhuo Kang
- Academy for Advanced Interdisciplinary Science and Technology, Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing 100083, P. R. China.,State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, P. R. China
| | - Yue Zhang
- Academy for Advanced Interdisciplinary Science and Technology, Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing 100083, P. R. China.,State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, P. R. China
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14
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Tan P, Ding K, Zhang X, Ni Z, Ostrikov KK, Gu X, Nan H, Xiao S. Bidirectional doping of two-dimensional thin-layer transition metal dichalcogenides using soft ammonia plasma. NANOSCALE 2021; 13:15278-15284. [PMID: 34486617 DOI: 10.1039/d1nr03917b] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Because of suitable band gap and high mobility, two-dimensional transition metal dichalcogenide (TMD) materials are promising in future microelectronic devices. However, controllable p-type and n-type doping of TMDs is still a challenge. Herein, we develop a soft plasma doping concept and demonstrate both n-type and p-type doping for TMDs including MoS2 and WS2 through adjusting the plasma working parameters. In particular, p-type doping of MoS2 can be realized when the radio frequency (RF) power is relatively small and the processing time is short: the off-state current increases from ∼10-10 A to ∼10-8 A, the threshold voltage is positively shifted from -26.2 V to 8.3 V, and the mobility increases from 7.05 cm2 V-1 s-1 to 16.52 cm2 V-1 s-1. Under a relatively large RF power and long processing time, n-type doping was realized for MoS2: the threshold voltage was negatively shifted from 6.8 V to -13.3 V and the mobility is reduced from 10.32 cm2 V-1 s-1 to 3.2 cm2 V-1 s-1. For the former, suitable plasma treatment can promote the substitution of N elements for S vacancies and lead to p-type doping, thus reducing the defect density and increasing the mobility value. For the latter, due to excessive plasma treatment, more S vacancies will be produced, leading to heavier n-type doping as well as a decrease in mobility. We confirm the results by systematically analyzing the optical, compositional, thickness and structural characteristics of the samples before and after such soft plasma treatments via Raman, photoluminescence (PL), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) measurements. Due to its nondestructive and expandable nature and compatibility with the current microelectronics industry, this potentially generic method may be used as a reliable technology for the development of diverse and functional TMD-based devices.
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Affiliation(s)
- Pu Tan
- Engineering Research Center of IoT Technology Applications (Ministry of Education), Department of Electronic Engineering, Jiangnan University, Wuxi 214122, China.
| | - Kaixuan Ding
- Engineering Research Center of IoT Technology Applications (Ministry of Education), Department of Electronic Engineering, Jiangnan University, Wuxi 214122, China.
| | - Xiumei Zhang
- School of Science, Jiangnan University, Wuxi 214122, China
| | - Zhenhua Ni
- Department of Physics and Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 211189, China
| | - Kostya Ken Ostrikov
- School of Chemistry and Physics and QUT Centre for Materials Science, Queensland University of Technology (QUT), Brisbane, QLD 4000, Australia
| | - Xiaofeng Gu
- Engineering Research Center of IoT Technology Applications (Ministry of Education), Department of Electronic Engineering, Jiangnan University, Wuxi 214122, China.
| | - Haiyan Nan
- Engineering Research Center of IoT Technology Applications (Ministry of Education), Department of Electronic Engineering, Jiangnan University, Wuxi 214122, China.
| | - Shaoqing Xiao
- Engineering Research Center of IoT Technology Applications (Ministry of Education), Department of Electronic Engineering, Jiangnan University, Wuxi 214122, China.
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15
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Rao R, Kim H, Perea-López N, Terrones M, Maruyama B. Interaction of gases with monolayer WS 2: an in situ spectroscopy study. NANOSCALE 2021; 13:11470-11477. [PMID: 34160535 DOI: 10.1039/d1nr01483h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The optical and electronic properties of two-dimensional (2D) materials can be tuned through physical and chemical adsorption of gases. They are also ideal sensor platforms, where charge transfer from the adsorbate can induce a measurable change in the electrical resistance within a device configuration. While 2D materials-based gas sensors exhibit high sensitivity, questions exist regarding the direction of charge transfer and the role of lattice defects during sensing. Here we measured the dynamics of adsorption of NO2 and NH3 on monolayer WS2 using in situ photoluminescence (PL) and resonance Raman spectroscopy. Experiments were conducted across a temperature range of 25-250 °C and gas concentrations between 5-650 ppm. The PL emission energies blue- and red-shifted when exposed to NO2 and NH3, respectively, and the magnitude of the shift depended on the gas concentration as well as the temperature down to the lowest concentration of 5 ppm. Analysis of the adsorption kinetics revealed an exponential increase in the intensities of the trion peaks with temperature, with apparent activation energies similar to barriers for migration of sulfur vacancies in the WS2 lattice. The corresponding Resonance Raman spectra allowed the simultaneous measurement of the defect-induced LA mode. A positive correlation between the defect densities and the shifts in the PL emission energies establish lattice defects such as sulfur vacancies as the preferential sites for gas adsorption. Moreover, an increase in defect densities with temperature in the presence of NO2 and NH3 suggests that these gases may also play a role in the creation of lattice defects. Our study provides key mechanistic insights into gas adsorption on monolayer WS2, and highlights the potential for future development of spectroscopy-based gas sensors based on 2D materials.
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Affiliation(s)
- Rahul Rao
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, OH 45433, USA.
| | - Hyunil Kim
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, OH 45433, USA.
| | - Nestor Perea-López
- Department of Physics and Center for Two-Dimensional and Layered Materials, The Pennsylvania University, State College, PA, USA
| | - Mauricio Terrones
- Department of Physics and Center for Two-Dimensional and Layered Materials, The Pennsylvania University, State College, PA, USA and Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802, USA and Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
| | - Benji Maruyama
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, OH 45433, USA.
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16
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Zhang X, Liao Q, Kang Z, Liu B, Liu X, Ou Y, Xiao J, Du J, Liu Y, Gao L, Gu L, Hong M, Yu H, Zhang Z, Duan X, Zhang Y. Hidden Vacancy Benefit in Monolayer 2D Semiconductors. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2007051. [PMID: 33448081 DOI: 10.1002/adma.202007051] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 12/02/2020] [Indexed: 06/12/2023]
Abstract
Monolayer 2D semiconductors (e.g., MoS2 ) are of considerable interest for atomically thin transistors but generally limited by insufficient carrier mobility or driving current. Minimizing the lattice defects in 2D semiconductors represents a common strategy to improve their electronic properties, but has met with limited success to date. Herein, a hidden benefit of the atomic vacancies in monolayer 2D semiconductors to push their performance limit is reported. By purposely tailoring the sulfur vacancies (SVs) to an optimum density of 4.7% in monolayer MoS2 , an unusual mobility enhancement is obtained and a record-high carrier mobility (>115 cm2 V-1 s-1 ) is achieved, realizing monolayer MoS2 transistors with an exceptional current density (>0.60 mA µm-1 ) and a record-high on/off ratio >1010 , and enabling a logic inverter with an ultrahigh voltage gain >100. The systematic transport studies reveal that the counterintuitive vacancy-enhanced transport originates from a nearest-neighbor hopping conduction model, in which an optimum SV density is essential for maximizing the charge hopping probability. Lastly, the vacancy benefit into other monolayer 2D semiconductors is further generalized; thus, a general strategy for tailoring the charge transport properties of monolayer materials is defined.
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Affiliation(s)
- Xiankun Zhang
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Qingliang Liao
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Zhuo Kang
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Baishan Liu
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Xiaozhi Liu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Collaborative Innovation Center of Quantum Matter, Beijing, 100190, China
| | - Yang Ou
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Jiankun Xiao
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Junli Du
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Yihe Liu
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Li Gao
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Lin Gu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Collaborative Innovation Center of Quantum Matter, Beijing, 100190, China
| | - Mengyu Hong
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Huihui Yu
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Zheng Zhang
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Xiangfeng Duan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095, USA
| | - Yue Zhang
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
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17
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Synthesis and Spectral Characteristics Investigation of the 2D-2D vdWs Heterostructure Materials. Int J Mol Sci 2021; 22:ijms22031246. [PMID: 33513931 PMCID: PMC7866235 DOI: 10.3390/ijms22031246] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 01/24/2021] [Accepted: 01/26/2021] [Indexed: 11/16/2022] Open
Abstract
Due to the attractive optical and electrical properties, van der Waals (vdWs) heterostructures constructed from the different two-dimensional materials have received widespread attention. Here, MoS2/h-BN, MoS2/graphene, WS2/h-BN, and WS2/graphene vdWs heterostructures are successfully prepared by the CVD and wet transfer methods. The distribution, Raman and photoluminescence (PL) spectra of the above prepared heterostructure samples can be respectively observed and tested by optical microscopy and Raman spectrometry, which can be used to study their growth mechanisms and optical properties. Meanwhile, the uniformity and composition distribution of heterostructure films can also be analyzed by the Raman and PL spectra. The internal mechanism of Raman and PL spectral changes can be explained by comparing and analyzing the PL and Raman spectra of the junction and non-junction regions between 2D-2D vdWs heterostructure materials, and the effect of laser power on the optical properties of heterostructure materials can also be analyzed. These heterostructure materials exhibit novel and unique optical characteristics at the stacking or junction, which can provide a reliable experimental basis for the preparation of suitable TMDs heterostructure materials with excellent performance.
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18
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Tao Y, Yuan J, Qian X, Meng Q, Zhu J, He G, Chen H. Spinel-type FeNi 2S 4 with rich sulfur vacancies grown on reduced graphene oxide toward enhanced supercapacitive performance. Inorg Chem Front 2021. [DOI: 10.1039/d0qi01460e] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Due to the coexistence of rich sulfur vacancies and rGO, the r-FeNi2S4-rGO electrode shows a superior specific capacitance.
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Affiliation(s)
- Yingrui Tao
- Key Laboratory of Advanced Catalytic Materials and Technology
- Advanced Catalysis and Green Manufacturing Collaborative Innovation Center
- Changzhou University
- Changzhou
- China
| | - Jingjing Yuan
- Key Laboratory of Advanced Catalytic Materials and Technology
- Advanced Catalysis and Green Manufacturing Collaborative Innovation Center
- Changzhou University
- Changzhou
- China
| | - Xingyue Qian
- Key Laboratory of Advanced Catalytic Materials and Technology
- Advanced Catalysis and Green Manufacturing Collaborative Innovation Center
- Changzhou University
- Changzhou
- China
| | - Qi Meng
- Key Laboratory of Advanced Catalytic Materials and Technology
- Advanced Catalysis and Green Manufacturing Collaborative Innovation Center
- Changzhou University
- Changzhou
- China
| | - Junwu Zhu
- School of Chemical Engineering
- Nanjing University of Science and Technology
- Nanjing
- China
| | - Guangyu He
- Key Laboratory of Advanced Catalytic Materials and Technology
- Advanced Catalysis and Green Manufacturing Collaborative Innovation Center
- Changzhou University
- Changzhou
- China
| | - Haiqun Chen
- Key Laboratory of Advanced Catalytic Materials and Technology
- Advanced Catalysis and Green Manufacturing Collaborative Innovation Center
- Changzhou University
- Changzhou
- China
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19
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Su HY, Ma X, Sun C, Sun K. A synergetic effect between a single Cu site and S vacancy on an MoS 2 basal plane for methanol synthesis from syngas. Catal Sci Technol 2021. [DOI: 10.1039/d1cy00003a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Compared to MoS2(001), the synergetic effect between the single Cu site and S vacancy on Cu/MoS2(001) destabilizes O, which not only increases the CO hydrogenation rate by 5 orders of magnitude, but leads to the selectivity switch from CH4 to CH3OH.
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Affiliation(s)
- Hai-Yan Su
- School of Chemical Engineering and Energy Technology
- Dongguan University of Technology
- Dongguan 523808
- China
| | - Xiufang Ma
- Shenzhen Key Laboratory of Advanced Thin Films and Applications
- College of Physics and Optoelectronic Engineering
- Shenzhen University
- Shenzhen 518060
- China
| | - Chenghua Sun
- Centre for Translational Atomaterials
- Swinburne University of Technology
- Hawthorn
- Australia
| | - Keju Sun
- Key Laboratory of Applied Chemistry
- College of Environmental and Chemical Engineering
- Yanshan University
- Qinhuangdao 066004
- China
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20
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Han T, Liu H, Wang S, Chen S, Yang K. Research on the Preparation and Spectral Characteristics of Graphene/TMDs Hetero-structures. NANOSCALE RESEARCH LETTERS 2020; 15:219. [PMID: 33237351 PMCID: PMC7688792 DOI: 10.1186/s11671-020-03439-1] [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: 06/08/2020] [Accepted: 10/26/2020] [Indexed: 06/11/2023]
Abstract
The Van der Waals (vdWs) hetero-structures consist of two-dimensional materials have received extensive attention, which is due to its attractive electrical and optoelectronic properties. In this paper, the high-quality large-size graphene film was first prepared by the chemical vapor deposition (CVD) method; then, graphene film was transferred to SiO2/Si substrate; next, the graphene/WS2 and graphene/MoS2 hetero-structures were prepared by the atmospheric pressure chemical vapor deposition method, which can be achieved by directly growing WS2 and MoS2 material on graphene/SiO2/Si substrate. Finally, the test characterization of graphene/TMDs hetero-structures was performed by AFM, SEM, EDX, Raman and PL spectroscopy to obtain and grasp the morphology and luminescence laws. The test results show that graphene/TMDs vdWs hetero-structures have the very excellent film quality and spectral characteristics. There is the built-in electric field at the interface of graphene/TMDs heterojunction, which can lead to the effective separation of photo-generated electron-hole pairs. Monolayer WS2 and MoS2 material have the strong broadband absorption capabilities, the photo-generated electrons from WS2 can transfer to the underlying p-type graphene when graphene/WS2 hetero-structures material is exposed to the light, and the remaining holes can induced the light gate effect, which is contrast to the ordinary semiconductor photoconductors. The research on spectral characteristics of graphene/TMDs hetero-structures can pave the way for the application of novel optoelectronic devices.
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Affiliation(s)
- Tao Han
- Key Laboratory for Wide-Bandgap Semiconductor Materials and Devices of Education, the School of Microelectronics, Xidian University, Xi'an, 710071, China
| | - Hongxia Liu
- Key Laboratory for Wide-Bandgap Semiconductor Materials and Devices of Education, the School of Microelectronics, Xidian University, Xi'an, 710071, China.
| | - Shulong Wang
- Key Laboratory for Wide-Bandgap Semiconductor Materials and Devices of Education, the School of Microelectronics, Xidian University, Xi'an, 710071, China
| | - Shupeng Chen
- Key Laboratory for Wide-Bandgap Semiconductor Materials and Devices of Education, the School of Microelectronics, Xidian University, Xi'an, 710071, China
| | - Kun Yang
- Key Laboratory for Wide-Bandgap Semiconductor Materials and Devices of Education, the School of Microelectronics, Xidian University, Xi'an, 710071, China
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21
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Peña Román RJ, Auad Y, Grasso L, Alvarez F, Barcelos ID, Zagonel LF. Tunneling-current-induced local excitonic luminescence in p-doped WSe 2 monolayers. NANOSCALE 2020; 12:13460-13470. [PMID: 32614018 DOI: 10.1039/d0nr03400b] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We have studied the excitonic properties of exfoliated tungsten diselenide (WSe2) monolayers transferred to gold substrates using the tunneling current in a Scanning Tunneling Microscope (STM) operated in air to excite the light emission locally. In obtained spectra, emission energies are independent of the applied bias voltage and resemble photoluminescence (PL) results, indicating that, in both cases, the light emission is due to neutral and charged exciton recombination. Interestingly, the electron injection rate, that is, the tunneling current, can be used to control the ratio of charged to neutral exciton emission. The obtained quantum yield in the transition metal dichalcogenide (TMD) is ∼5 × 10-7 photons per electron. The proposed excitation mechanism is the direct injection of carriers into the conduction band. The monolayer WSe2 presents bright and dark defects spotted by STM images performed under UHV. STS confirms the sample as p-doped, possibly as a net result of the observed defects. The presence of an interfacial water layer decouples the monolayer from the gold support and allows excitonic emission from the WSe2 monolayer. The creation of a water layer is an inherent feature of the sample transferring process due to the ubiquitous air moisture. Consequently, vacuum thermal annealing, which removes the water layer, quenches excitonic luminescence from the TMD. The tunneling current can locally displace water molecules leading to excitonic emission quenching and to plasmonic emission due to the gold substrate. The present findings extend the use and the understanding of STM induced light emission (STM-LE) on semiconducting TMDs to probe exciton emission and dynamics with high spatial resolution.
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Affiliation(s)
- Ricardo Javier Peña Román
- Applied Physics Department, "Gleb Wataghin" Institute of Physics, University of Campinas - UNICAMP, 13083-859, Campinas, SP, Brazil.
| | - Yves Auad
- Applied Physics Department, "Gleb Wataghin" Institute of Physics, University of Campinas - UNICAMP, 13083-859, Campinas, SP, Brazil.
| | - Lucas Grasso
- Applied Physics Department, "Gleb Wataghin" Institute of Physics, University of Campinas - UNICAMP, 13083-859, Campinas, SP, Brazil.
| | - Fernando Alvarez
- Applied Physics Department, "Gleb Wataghin" Institute of Physics, University of Campinas - UNICAMP, 13083-859, Campinas, SP, Brazil.
| | - Ingrid David Barcelos
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), 13083-970, Campinas, SP, Brazil
| | - Luiz Fernando Zagonel
- Applied Physics Department, "Gleb Wataghin" Institute of Physics, University of Campinas - UNICAMP, 13083-859, Campinas, SP, Brazil.
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22
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Fu M, Liang L, Zou Q, Nguyen GD, Xiao K, Li AP, Kang J, Wu Z, Gai Z. Defects in Highly Anisotropic Transition-Metal Dichalcogenide PdSe 2. J Phys Chem Lett 2020; 11:740-746. [PMID: 31880944 DOI: 10.1021/acs.jpclett.9b03312] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The atomic and electronic structures of pristine PdSe2 as well as various intrinsic vacancy defects in PdSe2 are studied comprehensively by combining scanning tunneling microscopy, spectroscopy, and density functional theory calculations. Other than the topmost Se atoms, sublayer Pd atoms and the intrinsic Pd and Se vacancy defects are identified. Both VSe and VPd defects induce defect states near the Fermi level. As a result, the vacancy defects can be negatively charged by a tip gating effect. At negative sample bias, the screened Coulomb interaction between the scanning tunneling microscopy (STM) tip and the charged vacancies creates a disk-like protrusion around the VPd and crater-like features around VSe. The magnification effect of the long-range charge localization at the charged defect site makes sublayer defects as deep as 1 nm visible even in STM images. This result proves that by gating the probe, scanning probe microscopy can be used as an easy tool for characterizing sublayer defects in a nondestructive way.
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Affiliation(s)
- Mingming Fu
- Fujian Provincial Key Laboratory of Semiconductors and Applications, Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Department of Physics , Xiamen University , Xiamen , Fujian Province 361005 , P.R. China
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Liangbo Liang
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Qiang Zou
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Giang D Nguyen
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Kai Xiao
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - An-Ping Li
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Junyong Kang
- Fujian Provincial Key Laboratory of Semiconductors and Applications, Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Department of Physics , Xiamen University , Xiamen , Fujian Province 361005 , P.R. China
| | - Zhiming Wu
- Fujian Provincial Key Laboratory of Semiconductors and Applications, Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Department of Physics , Xiamen University , Xiamen , Fujian Province 361005 , P.R. China
| | - Zheng Gai
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
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Li J, Chen X, Xiao Y, Li S, Zhang G, Diao X, Yan H, Zhang Y. A tunable floating-base bipolar transistor based on a 2D material homojunction realized using a solid ionic dielectric material. NANOSCALE 2019; 11:22531-22538. [PMID: 31746898 DOI: 10.1039/c9nr07597f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Floating-base bipolar transistors are widely used semiconductor devices because they could both amplify signal current and suppress noise. Employing two-dimensional (2D) materials of ultrahigh photoelectric properties could further improve the device performance. Due to the difficulty in doping, homojunctions are usually not realizable for many 2D materials. Instead, a heterojunction of various 2D materials of different Fermi levels is usually needed. However, the material interface of a heterojunction deteriorates device performance and makes the fabrication process difficult. Here, the doping difficulties have been solved by utilizing a solid ionic dielectric material (LiTaO3) and a floating-base bipolar transistor based on a 2D material (monolayer MoS2 here) homojunction is realized. The transistor shows tunable ambipolar transport characteristics. Particularly, under illumination, the amplification coefficient of a phototransistor can be optimized by changing the gate voltage. The optimized photoresponsivity of the device could reach up to 7.9 A W-1 with an ultrahigh detectivity of 3.39 × 1011 Jones. The overall fabrication processing is compatible to conventional processing. This design can effectively extend the application of 2D materials.
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Affiliation(s)
- Jingfeng Li
- College of Materials Science and Engineering and Key Laboratory of Advanced Functional Materials, Education Ministry of China, Beijing University of Technology, Beijing, 100124, China.
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Zhao H, Wu H, Wu J, Li J, Wang Y, Zhang Y, Liu H. Preparation of MoS2/WS2 nanosheets by liquid phase exfoliation with assistance of epigallocatechin gallate and study as an additive for high-performance lithium-sulfur batteries. J Colloid Interface Sci 2019; 552:554-562. [DOI: 10.1016/j.jcis.2019.05.080] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 05/22/2019] [Accepted: 05/24/2019] [Indexed: 01/27/2023]
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25
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Hu W, Tan H, Duan H, Li G, Li N, Ji Q, Lu Y, Wang Y, Sun Z, Hu F, Wang C, Yan W. Synergetic Effect of Substitutional Dopants and Sulfur Vacancy in Modulating the Ferromagnetism of MoS 2 Nanosheets. ACS APPLIED MATERIALS & INTERFACES 2019; 11:31155-31161. [PMID: 31385491 DOI: 10.1021/acsami.9b09165] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The activation and modulation of the magnetism of MoS2 nanosheets are critical to the development of their application in next-generation spintronics. Here, we report a synergetic strategy to induce and modulate the ferromagnetism of the originally nonmagnetic MoS2 nanosheets. A two-step experimental method was used to simultaneously introduce substitutional V dopants and sulfur vacancy (Vs) in the MoS2 nanosheet host, showing an air-stable and adjustable ferromagnetic response at room temperature. The ferromagnetism could be modulated by varying the content of Vs through Ar plasma irradiation of different periods, with a maximum saturation magnetization of 0.011 emu g-1 reached at the irradiation time of 6 s (s). Experimental characterizations and first-principles calculations suggest that the adjustable magnetization is attributed to the synergetic effect of the substitutional V dopants and Vs in modulating the band structure of MoS2 nanosheets, resulting from the strong hybridization between the V 3d state and the Vs-induced impurity bands. This work suggests that the synergetic effect of substitutional V atoms and Vs is a promising route for tuning the magnetic interactions in two-dimensional nanostructures.
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Affiliation(s)
- Wei Hu
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , P. R. China
| | - Hao Tan
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , P. R. China
| | - Hengli Duan
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , P. R. China
| | - Guinan Li
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , P. R. China
| | - Na Li
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , P. R. China
| | - Qianqian Ji
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , P. R. China
| | - Ying Lu
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , P. R. China
| | - Yao Wang
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , P. R. China
| | - Zhihu Sun
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , P. R. China
| | - Fengchun Hu
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , P. R. China
| | - Chao Wang
- Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology , Chinese Academy of Sciences , Hefei 230031 , Anhui , P. R. China
| | - Wensheng Yan
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , P. R. China
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Schuler B, Qiu DY, Refaely-Abramson S, Kastl C, Chen CT, Barja S, Koch RJ, Ogletree DF, Aloni S, Schwartzberg AM, Neaton JB, Louie SG, Weber-Bargioni A. Large Spin-Orbit Splitting of Deep In-Gap Defect States of Engineered Sulfur Vacancies in Monolayer WS_{2}. PHYSICAL REVIEW LETTERS 2019; 123:076801. [PMID: 31491121 DOI: 10.1103/physrevlett.123.076801] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 05/29/2019] [Indexed: 06/10/2023]
Abstract
Structural defects in 2D materials offer an effective way to engineer new material functionalities beyond conventional doping. We report on the direct experimental correlation of the atomic and electronic structure of a sulfur vacancy in monolayer WS_{2} by a combination of CO-tip noncontact atomic force microscopy and scanning tunneling microscopy. Sulfur vacancies, which are absent in as-grown samples, were deliberately created by annealing in vacuum. Two energetically narrow unoccupied defect states followed by vibronic sidebands provide a unique fingerprint of this defect. Direct imaging of the defect orbitals, together with ab initio GW calculations, reveal that the large splitting of 252±4 meV between these defect states is induced by spin-orbit coupling.
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Affiliation(s)
- Bruno Schuler
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Diana Y Qiu
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Sivan Refaely-Abramson
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Christoph Kastl
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Walter Schottky Institute and Physics Department, Technical University of Munich, 85748 Garching, Germany
| | - Christopher T Chen
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Sara Barja
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Departamento de Física de Materiales, Centro de Física de Materiales, University of the Basque Country UPV/EHU-CSIC, Donostia-San Sebastián 20018, Spain
- Ikerbasque, Basque Foundation for Science, Bilbao 48013, Spain
- Donostia International Physics Center, Donostia-San Sebastin 20018, Spain
| | - Roland J Koch
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - D Frank Ogletree
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Shaul Aloni
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Adam M Schwartzberg
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Jeffrey B Neaton
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
- Kavli Energy Nanoscience Institute at Berkeley, Berkeley, California 94720, USA
| | - Steven G Louie
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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27
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Barja S, Refaely-Abramson S, Schuler B, Qiu DY, Pulkin A, Wickenburg S, Ryu H, Ugeda MM, Kastl C, Chen C, Hwang C, Schwartzberg A, Aloni S, Mo SK, Frank Ogletree D, Crommie MF, Yazyev OV, Louie SG, Neaton JB, Weber-Bargioni A. Identifying substitutional oxygen as a prolific point defect in monolayer transition metal dichalcogenides. Nat Commun 2019; 10:3382. [PMID: 31358753 PMCID: PMC6662818 DOI: 10.1038/s41467-019-11342-2] [Citation(s) in RCA: 100] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 07/05/2019] [Indexed: 12/24/2022] Open
Abstract
Chalcogen vacancies are generally considered to be the most common point defects in transition metal dichalcogenide (TMD) semiconductors because of their low formation energy in vacuum and their frequent observation in transmission electron microscopy studies. Consequently, unexpected optical, transport, and catalytic properties in 2D-TMDs have been attributed to in-gap states associated with chalcogen vacancies, even in the absence of direct experimental evidence. Here, we combine low-temperature non-contact atomic force microscopy, scanning tunneling microscopy and spectroscopy, and state-of-the-art ab initio density functional theory and GW calculations to determine both the atomic structure and electronic properties of an abundant chalcogen-site point defect common to MoSe2 and WS2 monolayers grown by molecular beam epitaxy and chemical vapor deposition, respectively. Surprisingly, we observe no in-gap states. Our results strongly suggest that the common chalcogen defects in the described 2D-TMD semiconductors, measured in vacuum environment after gentle annealing, are oxygen substitutional defects, rather than vacancies.
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Affiliation(s)
- Sara Barja
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
- Departamento de Física de Materiales, Centro de Física de Materiales, University of the Basque Country UPV/EHU-CSIC, Donostia-San Sebastián, 20018, Spain.
- IKERBASQUE, Basque Foundation for Science, Bilbao, 48013, Spain.
- Donostia International Physics Center, Donostia-San Sebastián, 20018, Spain.
| | - Sivan Refaely-Abramson
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Physics, University of California at Berkeley, Berkeley, Berkeley, CA, 94720, USA
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Bruno Schuler
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Diana Y Qiu
- Department of Physics, University of California at Berkeley, Berkeley, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Artem Pulkin
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Sebastian Wickenburg
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Hyejin Ryu
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, Korea
| | - Miguel M Ugeda
- Departamento de Física de Materiales, Centro de Física de Materiales, University of the Basque Country UPV/EHU-CSIC, Donostia-San Sebastián, 20018, Spain
- IKERBASQUE, Basque Foundation for Science, Bilbao, 48013, Spain
- Donostia International Physics Center, Donostia-San Sebastián, 20018, Spain
| | - Christoph Kastl
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Christopher Chen
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Choongyu Hwang
- Department of Physics, Pusan National University, Busan, 46241, Korea
| | - Adam Schwartzberg
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Shaul Aloni
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Sung-Kwan Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - D Frank Ogletree
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Michael F Crommie
- Department of Physics, University of California at Berkeley, Berkeley, Berkeley, CA, 94720, USA
- Kavli Energy NanoSciences Institute at the University of California Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, Berkeley, CA, 94720, USA
| | - Oleg V Yazyev
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Steven G Louie
- Department of Physics, University of California at Berkeley, Berkeley, Berkeley, CA, 94720, USA.
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
| | - Jeffrey B Neaton
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
- Department of Physics, University of California at Berkeley, Berkeley, Berkeley, CA, 94720, USA.
- Kavli Energy NanoSciences Institute at the University of California Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, Berkeley, CA, 94720, USA.
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MoS 2 Coexisting in 1T and 2H Phases Synthesized by Common Hydrothermal Method for Hydrogen Evolution Reaction. NANOMATERIALS 2019; 9:nano9060844. [PMID: 31159477 PMCID: PMC6630712 DOI: 10.3390/nano9060844] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 05/29/2019] [Indexed: 01/15/2023]
Abstract
Molybdenum disulfide has been one of the most studied hydrogen evolution catalyst materials in recent years, but its disadvantages, such as poor conductivity, hinder its further development. Here, we employ the common hydrothermal method, followed by an additional solvothermal method to construct an uncommon molybdenum disulfide with two crystal forms of 1T and 2H to improve catalytic properties. The low overpotential (180 mV) and small Tafel slope (88 mV/dec) all indicated that molybdenum disulfide had favorable catalytic performance for hydrogen evolution. Further conjunctions revealed that the improvement of performance was probably related to the structural changes brought about by the 1T phase and the resulting sulfur vacancies, which could be used as a reference for the further application of MoS2.
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29
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Liu L, Lenferink EJ, Wei G, Stanev TK, Speiser N, Stern NP. Electrical Control of Circular Photogalvanic Spin-Valley Photocurrent in a Monolayer Semiconductor. ACS APPLIED MATERIALS & INTERFACES 2019; 11:3334-3341. [PMID: 30582322 DOI: 10.1021/acsami.8b17476] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In a monolayer transition metal dichalcogenide (TMDC) that lacks structural inversion symmetry, spin degeneracy is lifted by strong spin-orbit coupling, and a distinctive spin-valley locking allows for the creation of valley-locked spin-polarized carriers with a circularly polarized optical excitation. When excited carriers also have net in-plane momentum, spin-polarized photocurrents can be generated at ambient temperature without magnetic fields or materials. The behavior of these spin-polarized photocurrents in monolayer TMDC remains largely unexplored. In this work, we demonstrate the tuning of spin-valley photocurrent generated from the circularly polarized photogalvanic effect in monolayer MoS2, including magnitude and polarization degree, by purely electric means at room temperature. The magnitude of spin-polarized photocurrent can be modulated up to 45 times larger, and the polarization degree of the total photocurrent can be tuned significantly (here from 0.5 to 16.6%) by gate control. Combined with the atomic thickness and wafer-scale growth capabilities of monolayer TMDC, the efficient electrical tuning of spin-valley photocurrent suggests a pathway to achieve spin-logic processing by local gate architectures in monolayer opto-spintronic devices.
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Affiliation(s)
- Lei Liu
- Department of Materials Science and Engineering, College of Engineering , Peking University , Beijing 100871 , P. R. China
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30
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Zhang X, Zhang S, Xie Y, Huang J, Wang L, Cui Y, Wang J. Tailoring the nonlinear optical performance of two-dimensional MoS 2 nanofilms via defect engineering. NANOSCALE 2018; 10:17924-17932. [PMID: 30226259 DOI: 10.1039/c8nr05653f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Defect engineering plays a key role in determining the catalytic and optical properties of two-dimensional (2D) materials such as molybdenum disulfide (MoS2) in their practical applications in optical and photonic devices. Here, we report a direct strategy for the fabrication of wafer-scale 2D MoS2 nanofilms with tunable sulfur (S) vacancies and crystallinity by a modified solvothermal method via a polyelectrolyte-assisted annealing process. Our results demonstrate that the S vacancies in MoS2 nanofilms can induce saturable absorption (SA) in MoS2 by introducing new energy bands within the band gap of MoS2, and the crystallinity has a significant effect on the two-photon absorption (TPA) coefficient of MoS2 nanofilms. The SA responses in MoS2 will gradually dominate the nonlinear optical (NLO) behavior of MoS2 with a lower saturable intensity along with increasing the S vacancies. The TPA coefficient of the MoS2 nanofilms with increased crystallinity is improved to (4.3 ± 0.5) × 102 cm GW-1 on increasing the crystallinity of MoS2 films, over four times larger than that of their counterpart with relatively low crystallinity. Additionally, the damage threshold of MoS2 nanofilms after polyelectrolyte-assisted annealing treatment is greatly improved to ∼74.1 GW cm-2 compared to ∼32.6 GW cm-2 of their counterpart with few S vacancies and relatively low crystallinity, due to the increased crystallinity and partial oxidation of MoS2. This work sheds light on how the defects tailor the nonlinear optical properties of 2D MoS2 nanofilms and affords an effective strategy for defect engineering via a polyelectrolyte-assisted annealing process, which can be applied to other 2D transition metal dichalcogenides.
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Affiliation(s)
- Xiaoyan Zhang
- Laboratory of Micro-Nano Photonic and Optoelectronic Materials and Devices, Shanghai Institute of Optics and Fine Mechanics (SIOM), Chinese Academy of Sciences (CAS), Shanghai 201800, China.
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Tan Q, Wang Q, Liu Y, Liu C, Feng X, Yu D. Enhanced magnetic properties and tunable Dirac point of graphene/Mn-doped monolayer MoS 2 heterostructures. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:305304. [PMID: 29900880 DOI: 10.1088/1361-648x/aacca2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Graphene is one of the most promising spintronic materials due to its high carrier mobility. However, the absence of a band gap and ferromagnetic order in graphene seriously limit its applications in spintronics. How to utilize its high carrier mobility as well as mediate its electronic structure remains a challenge. Herein, we design a novel composite, which is composed of graphene and Mn-doped monolayer MoS2. The magnetic properties and electronic structures of graphene/Mn-doped monolayer MoS2 heterostructures were studied by using density functional theory (DFT) with the van der Waals (vdW) correlations (DFT-D). We found that the heterostructures show increased magnetic moments and more stable ferromagnetic (FM) states compared with that of isolated Mn-doped MoS2 monolayer. Our further studies show that many electrons are transferred to Mn-doped MoS2 monolayer from graphene, which causes the Fermi level to shift down below the Dirac cone about 0.59 eV. The transfered electrons also enhance the FM coupling between Mn ions. Graphene is partially spin polarized because of the magnetic proximity effect, which leads to the spin-dependent gaps for spin-up (16.1 meV) and spin-down (5 meV) at Dirac point, respectively. The introduction of sulfur (S) vacancy to the interface results in a much more stable FM structure and a higher total magnetic moment of the FM state; furthermore, it raises the spin polarization of graphene π orbitals and opens up a small band gap of about 7 meV. These findings propose a new route to facilitate the design of spintronic devices which both need stable ferromagnetism and finite band gap.
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Affiliation(s)
- Qiuhong Tan
- College of Physics and Electronic Information, Yunnan Normal University, Yunnan Kunming 650500, People's Republic of China. Yunnan Provincial Key Laboratory for Photoelectric Information Technology, Yunnan Normal University, Yunnan Kunming 650500, People's Republic of China
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32
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Zhang X, Lai Z, Ma Q, Zhang H. Novel structured transition metal dichalcogenide nanosheets. Chem Soc Rev 2018; 47:3301-3338. [PMID: 29671441 DOI: 10.1039/c8cs00094h] [Citation(s) in RCA: 149] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Ultrathin two-dimensional (2D) layered transition metal dichalcogenides (TMDs) have attracted considerable attention owing to their unique properties and great potential in a wide range of applications. Great efforts have been devoted to the preparation of novel-structured TMD nanosheets by engineering their intrinsic structures at the atomic scale. Until now, a lot of new-structured TMD nanosheets, such as vacancy-containing TMDs, heteroatom-doped TMDs, TMD alloys, 1T'/1T phase and in-plane TMD crystal-phase heterostructures, TMD heterostructures and Janus TMD nanosheets, have been prepared. These materials exhibit unique properties and hold great promise in various applications, including electronics/optoelectronics, thermoelectrics, catalysis, energy storage and conversion and biomedicine. This review focuses on the most recent important discoveries in the preparation, characterization and application of these new-structured ultrathin 2D layered TMDs.
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Affiliation(s)
- Xiao Zhang
- Center for Programmable Materials, School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
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