2101
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Jin S, Yang G, Song H, Cui H, Wang C. Ultrathin Hexagonal 2D Co₂GeO₄ Nanosheets: Excellent Li-Storage Performance and ex Situ Investigation of Electrochemical Mechanism. ACS Appl Mater Interfaces 2015; 7:24932-24943. [PMID: 26486013 DOI: 10.1021/acsami.5b08446] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Two-dimensional (2D) nanostructures are a desirable configuration for lithium ion battery (LIB) electrodes due to their large open surface and short pathway for lithium ions. Therefore, exploring new anode materials with 2D structure could be a promising direction to develop high-performance LIBs. Herein, we synthesized a new type of 2D Ge-based double metal oxides for lithium storage. Ultrathin hexagonal Co2GeO4 nanosheets with nanochannels are prepared by a simple hydrothermal method. When used as LIB anode, the sample delivers excellent cyclability and rate capability. A highly stable capacity of 1026 mAhg(-1) was recorded after 150 cycles. Detailed morphology and phase evolutions were detected by TEM and EELS measurements. It is found that Co2GeO4 decomposed into Ge NPs which are evenly dispersed in amorphous Co/Li2O matrix during the cycling process. Interestingly, the in situ formed Co matrix could serve as a conductive network for electrochemical process of Ge. Moreover, aggregations of Ge NPs could be restricted by the ultrathin configuration and Co/Li2O skeleton, leading to unique structure stability. Hence, the large surface areas, ultrathin thickness, and atomically metal matrix finally bring the superior electrochemical performance.
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Affiliation(s)
- Shuaixing Jin
- The Key Laboratory of Low-Carbon Chemistry & Energy Conservation of Guangdong Province, ‡State Key Laboratory of Optoelectronic Materials and Technologies, and §School of Physics Science and Engineering, Sun Yat-sen (Zhongshan) University , Guangzhou 510275, People's Republic of China
| | - Gongzheng Yang
- The Key Laboratory of Low-Carbon Chemistry & Energy Conservation of Guangdong Province, ‡State Key Laboratory of Optoelectronic Materials and Technologies, and §School of Physics Science and Engineering, Sun Yat-sen (Zhongshan) University , Guangzhou 510275, People's Republic of China
| | - Huawei Song
- The Key Laboratory of Low-Carbon Chemistry & Energy Conservation of Guangdong Province, ‡State Key Laboratory of Optoelectronic Materials and Technologies, and §School of Physics Science and Engineering, Sun Yat-sen (Zhongshan) University , Guangzhou 510275, People's Republic of China
| | - Hao Cui
- The Key Laboratory of Low-Carbon Chemistry & Energy Conservation of Guangdong Province, ‡State Key Laboratory of Optoelectronic Materials and Technologies, and §School of Physics Science and Engineering, Sun Yat-sen (Zhongshan) University , Guangzhou 510275, People's Republic of China
| | - Chengxin Wang
- The Key Laboratory of Low-Carbon Chemistry & Energy Conservation of Guangdong Province, ‡State Key Laboratory of Optoelectronic Materials and Technologies, and §School of Physics Science and Engineering, Sun Yat-sen (Zhongshan) University , Guangzhou 510275, People's Republic of China
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2102
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Jing Y, Zhang X, Wu D, Zhao X, Zhou Z. High Carrier Mobility and Pronounced Light Absorption in Methyl-Terminated Germanene: Insights from First-Principles Computations. J Phys Chem Lett 2015; 6:4252-4258. [PMID: 26538040 DOI: 10.1021/acs.jpclett.5b01848] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
On the basis of Herd-Scuseria-Emzerhof hybrid functional (HSE06) within the framework of density functional theory (DFT), we have computationally explored the intrinsic electronic and optical properties of 2D methyl-terminated germanene (GeCH3). GeCH3 monolayer possesses an opportune direct band gap of 1.76 eV, which can be effectively tuned by applying elastic strain and decreases with increasing the tensile strain, while it increases with small compressive strain. Also, anisotropic carrier mobility was disclosed in the armchair (x) and zigzag (y) directions of GeCH3 monolayer. Moreover, GeCH3 monolayer shows significant light absorption in the visible and ultraviolet range of solar spectrum and is attractive for light harvesting. The results can help us better understand the intrinsic properties of GeCH3 and provide reliable guidance for its experimental applications to electronics and optoelectronics.
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Affiliation(s)
- Yu Jing
- Tianjin Key Laboratory of Metal and Molecule Based Material Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Computational Centre for Molecular Science, Institute of New Energy Material Chemistry, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Materials Science and Engineering, National Institute for Advanced Materials, Nankai University , Tianjin 300353, P. R. China
| | - Xu Zhang
- Tianjin Key Laboratory of Metal and Molecule Based Material Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Computational Centre for Molecular Science, Institute of New Energy Material Chemistry, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Materials Science and Engineering, National Institute for Advanced Materials, Nankai University , Tianjin 300353, P. R. China
| | - Dihua Wu
- Tianjin Key Laboratory of Metal and Molecule Based Material Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Computational Centre for Molecular Science, Institute of New Energy Material Chemistry, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Materials Science and Engineering, National Institute for Advanced Materials, Nankai University , Tianjin 300353, P. R. China
| | - Xudong Zhao
- Tianjin Key Laboratory of Metal and Molecule Based Material Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Computational Centre for Molecular Science, Institute of New Energy Material Chemistry, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Materials Science and Engineering, National Institute for Advanced Materials, Nankai University , Tianjin 300353, P. R. China
| | - Zhen Zhou
- Tianjin Key Laboratory of Metal and Molecule Based Material Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Computational Centre for Molecular Science, Institute of New Energy Material Chemistry, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Materials Science and Engineering, National Institute for Advanced Materials, Nankai University , Tianjin 300353, P. R. China
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2103
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Choi J, Chen H, Li F, Yang L, Kim SS, Naik RR, Ye PD, Choi JH. Nanomanufacturing of 2D Transition Metal Dichalcogenide Materials Using Self-Assembled DNA Nanotubes. Small 2015; 11:5520-5527. [PMID: 26313027 DOI: 10.1002/smll.201501431] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 07/23/2015] [Indexed: 06/04/2023]
Abstract
2D transition metal dichalcogenides (TMDCs) are nanomanufactured using a generalized strategy with self-assembled DNA nanotubes. DNA nanotubes of various lengths serve as lithographic etch masks for the dry etching of TMDCs. The nanostructured TMDCs are studied by atomic force microscopy, photoluminescence, and Raman spectroscopy. This parallel approach can be used to manufacture 2D TMDC nanostructures of arbitrary geometries with molecular-scale precision.
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Affiliation(s)
- Jungwook Choi
- School of Mechanical Engineering, Purdue University, West Lafayette, IN, 47907, USA
| | - Haorong Chen
- School of Mechanical Engineering, Purdue University, West Lafayette, IN, 47907, USA
| | - Feiran Li
- School of Mechanical Engineering, Purdue University, West Lafayette, IN, 47907, USA
| | - Lingming Yang
- School of Electrical and Computer Engineering, Birck Nanotechnology Center, Purdue University, West Lafayette, IN, 47907, USA
| | - Steve S Kim
- Materials & Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, OH, 45433, USA
| | - Rajesh R Naik
- Materials & Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, OH, 45433, USA
| | - Peide D Ye
- School of Electrical and Computer Engineering, Birck Nanotechnology Center, Purdue University, West Lafayette, IN, 47907, USA
| | - Jong Hyun Choi
- School of Mechanical Engineering, Purdue University, West Lafayette, IN, 47907, USA
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2104
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He X, Liu F, Hu P, Fu W, Wang X, Zeng Q, Zhao W, Liu Z. Chemical Vapor Deposition of High-Quality and Atomically Layered ReS₂. Small 2015; 11:5423-5429. [PMID: 26305164 DOI: 10.1002/smll.201501488] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 07/12/2015] [Indexed: 06/04/2023]
Abstract
Recently, anisotropic 2D materials, such as black phosphorus and rhenium disulfides (ReS2 ), have attracted a lot attention because of their unique applications on electronics and optoelectronics. In this work, the direct growth of high-quality ReS2 atomic layers and nanoribbons has been demonstrated by using chemical vapor deposition (CVD) method. A possible growth mechanism is proposed according to the controlled experiments. The CVD ReS2-based filed-effect transistors (FETs) show n-type semiconducting behavior with a current on/off ratio of ≈10(6) and a charge carrier mobility of ≈9.3 cm(2) Vs(-1). These results suggested that the quality of CVD grown ReS2 is comparable to mechanically exfoliated ReS2, which is also further supported by atomic force microscopy imaging, high-resolution transmission electron microscopy imaging and thickness-dependent Raman spectra. The study here indicates that CVD grown ReS2 may pave the way for the large-scale fabrication of ReS2-based high-performance optoelectronic devices, such as anisotropic FETs and polarization detection.
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Affiliation(s)
- Xuexia He
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Fucai Liu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Peng Hu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Wei Fu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Xingli Wang
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Qingsheng Zeng
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Wu Zhao
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
- School of Information Science and Technology, Northwest University, Xi'an, Shannxi, 710069, P. R. China
| | - Zheng Liu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
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2105
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Abstract
Two-dimensional (2D) materials present many unique materials concepts, including material properties that sometimes differ dramatically from those of their bulk counterparts. One of these properties, piezoelectricity, is important for micro- and nanoelectromechanical systems applications. Using symmetry analysis, we determine the independent piezoelectric coefficients for four groups of predicted and synthesized 2D materials. We calculate with density-functional perturbation theory the stiffness and piezoelectric tensors of these materials. We determine the in-plane piezoelectric coefficient d11 for 37 materials within the families of 2D metal dichalcogenides, metal oxides, and III-V semiconductor materials. A majority of the structures, including CrSe2, CrTe2, CaO, CdO, ZnO, and InN, have d11 coefficients greater than 5 pm/V, a typical value for bulk piezoelectric materials. Our symmetry analysis shows that buckled 2D materials exhibit an out-of-plane coefficient d31. We find that d31 for 8 III-V semiconductors ranges from 0.02 to 0.6 pm/V. From statistical analysis, we identify correlations between the piezoelectric coefficients and the electronic and structural properties of the 2D materials that elucidate the origin of the piezoelectricity. Among the 37 2D materials, CdO, ZnO, and CrTe2 stand out for their combination of large piezoelectric coefficient and low formation energy and are recommended for experimental exploration.
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Affiliation(s)
- Michael N Blonsky
- Department of Materials Science and Engineering, Cornell University , Ithaca, New York 14853, United States
| | - Houlong L Zhuang
- Department of Materials Science and Engineering, Cornell University , Ithaca, New York 14853, United States
| | - Arunima K Singh
- Department of Materials Science and Engineering, Cornell University , Ithaca, New York 14853, United States
| | - Richard G Hennig
- Department of Materials Science and Engineering, Cornell University , Ithaca, New York 14853, United States
- Department of Materials Science and Engineering, University of Florida , Gainesville, Florida 32611, United States
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2106
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Anasori B, Xie Y, Beidaghi M, Lu J, Hosler BC, Hultman L, Kent PRC, Gogotsi Y, Barsoum MW. Two-Dimensional, Ordered, Double Transition Metals Carbides (MXenes). ACS Nano 2015; 9:9507-9516. [PMID: 26208121 DOI: 10.1021/acsnano.5b03591] [Citation(s) in RCA: 474] [Impact Index Per Article: 52.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The higher the chemical diversity and structural complexity of two-dimensional (2D) materials, the higher the likelihood they possess unique and useful properties. Herein, density functional theory (DFT) is used to predict the existence of two new families of 2D ordered, carbides (MXenes), M'2M″C2 and M'2M″2C3, where M' and M″ are two different early transition metals. In these solids, M' layers sandwich M″ carbide layers. By synthesizing Mo2TiC2Tx, Mo2Ti2C3Tx, and Cr2TiC2Tx (where T is a surface termination), we validated the DFT predictions. Since the Mo and Cr atoms are on the outside, they control the 2D flakes' chemical and electrochemical properties. The latter was proven by showing quite different electrochemical behavior of Mo2TiC2Tx and Ti3C2Tx. This work further expands the family of 2D materials, offering additional choices of structures, chemistries, and ultimately useful properties.
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Affiliation(s)
- Babak Anasori
- Department of Materials Science & Engineering, Drexel University , Philadelphia, Pennsylvania 19104, United States
- A.J. Drexel Nanomaterials Institute, Drexel University , Philadelphia, Pennsylvania 19104, United States
| | - Yu Xie
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37381, United States
| | - Majid Beidaghi
- Department of Materials Science & Engineering, Drexel University , Philadelphia, Pennsylvania 19104, United States
- A.J. Drexel Nanomaterials Institute, Drexel University , Philadelphia, Pennsylvania 19104, United States
| | - Jun Lu
- Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University , SE-581 83 Linköping, Sweden
| | - Brian C Hosler
- Department of Materials Science & Engineering, Drexel University , Philadelphia, Pennsylvania 19104, United States
| | - Lars Hultman
- Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University , SE-581 83 Linköping, Sweden
| | - Paul R C Kent
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37381, United States
- Computer Science and Mathematics Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37381, United States
| | - Yury Gogotsi
- Department of Materials Science & Engineering, Drexel University , Philadelphia, Pennsylvania 19104, United States
- A.J. Drexel Nanomaterials Institute, Drexel University , Philadelphia, Pennsylvania 19104, United States
| | - Michel W Barsoum
- Department of Materials Science & Engineering, Drexel University , Philadelphia, Pennsylvania 19104, United States
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2107
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Cai SL, Zhang WG, Zuckermann RN, Li ZT, Zhao X, Liu Y. The Organic Flatland-Recent Advances in Synthetic 2D Organic Layers. Adv Mater 2015; 27:5762-5770. [PMID: 25735971 DOI: 10.1002/adma.201500124] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Revised: 01/27/2015] [Indexed: 06/04/2023]
Abstract
Ultrathin, 2D organic layers of sub-ten nanometer thicknesses and high aspect ratios have received a great deal of attention for their graphene-like topological features and emerging properties. Rational synthetic strategies have led to the realization of periodic 2D layers with unprecedented structural precision. Herein, recent progress on the synthesis of 2D organic layers, including methods based on both non-covalent and covalent interactions, is summarized, and potential applications are highlighted. Such 2D organic nanostructures have a brilliant future as prospective multifunctional materials, showing great promise as platforms for engineering novel optoelectronic, interfacial, and bioactive properties.
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Affiliation(s)
- Song-Liang Cai
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, US
- School of Chemistry and Environment, South China Normal University, Guangzhou, 510006, P.R. China
| | - Wei-Guang Zhang
- School of Chemistry and Environment, South China Normal University, Guangzhou, 510006, P.R. China
| | - Ronald N Zuckermann
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, US
| | - Zhan-Ting Li
- Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Department of Chemistry, Fudan University, 220 Handan Road, Shanghai, 200433, P.R. China
| | - Xin Zhao
- Key Laboratory of Synthetic and Self-Assembly Chemistry for Organic Functional Molecules, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Lu, Shanghai, 200032, P.R. China
| | - Yi Liu
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, US
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2108
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Mannebach EM, Li R, Duerloo KA, Nyby C, Zalden P, Vecchione T, Ernst F, Reid AH, Chase T, Shen X, Weathersby S, Hast C, Hettel R, Coffee R, Hartmann N, Fry AR, Yu Y, Cao L, Heinz TF, Reed EJ, Dürr HA, Wang X, Lindenberg AM. Dynamic Structural Response and Deformations of Monolayer MoS2 Visualized by Femtosecond Electron Diffraction. Nano Lett 2015; 15:6889-6895. [PMID: 26322659 DOI: 10.1021/acs.nanolett.5b02805] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Two-dimensional materials are subject to intrinsic and dynamic rippling that modulates their optoelectronic and electromechanical properties. Here, we directly visualize the dynamics of these processes within monolayer transition metal dichalcogenide MoS2 using femtosecond electron scattering techniques as a real-time probe with atomic-scale resolution. We show that optical excitation induces large-amplitude in-plane displacements and ultrafast wrinkling of the monolayer on nanometer length-scales, developing on picosecond time-scales. These deformations are associated with several percent peak strains that are fully reversible over tens of millions of cycles. Direct measurements of electron-phonon coupling times and the subsequent interfacial thermal heat flow between the monolayer and substrate are also obtained. These measurements, coupled with first-principles modeling, provide a new understanding of the dynamic structural processes that underlie the functionality of two-dimensional materials and open up new opportunities for ultrafast strain engineering using all-optical methods.
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Affiliation(s)
- Ehren M Mannebach
- Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States
| | - Renkai Li
- SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Karel-Alexander Duerloo
- Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States
| | - Clara Nyby
- Department of Chemistry, Stanford University , Stanford, California 94305, United States
| | - Peter Zalden
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Theodore Vecchione
- SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Friederike Ernst
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
- Department of Applied Physics, Stanford University , Stanford, California 94305, United States
- PULSE Institute, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Alexander Hume Reid
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Tyler Chase
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
- Department of Applied Physics, Stanford University , Stanford, California 94305, United States
| | - Xiaozhe Shen
- SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Stephen Weathersby
- SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Carsten Hast
- SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Robert Hettel
- SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Ryan Coffee
- SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Nick Hartmann
- SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Alan R Fry
- SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Yifei Yu
- Department of Materials Science and Engineering, North Carolina State University , Raleigh, North Carolina 27695, United States
| | - Linyou Cao
- Department of Materials Science and Engineering, North Carolina State University , Raleigh, North Carolina 27695, United States
| | - Tony F Heinz
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
- Department of Applied Physics, Stanford University , Stanford, California 94305, United States
- PULSE Institute, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Evan J Reed
- Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States
- PULSE Institute, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Hermann A Dürr
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Xijie Wang
- SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Aaron M Lindenberg
- Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
- PULSE Institute, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
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2109
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Abstract
Two-dimensional (2-D) materials including graphene and transition metal dichalcogenides (TMDs) are an exciting platform for ultrasensitive force and displacement detection in which the strong light-matter coupling is exploited in the optical control of nanomechanical motion. Here we report the optical excitation and displacement detection of a ∼ 3 nm thick MoS2 resonator in the strong-coupling regime, which has not previously been achieved in 2-D materials. Mechanical mode frequencies can be tuned by more than 12% by optical heating, and they exhibit avoided crossings indicative of strong intermode coupling. When the membrane is optically excited at the frequency difference between vibrational modes, normal mode splitting is observed, and the intermode energy exchange rate exceeds the mode decay rate by a factor of 15. Finite element and analytical modeling quantifies the extent of mode softening necessary to control intermode energy exchange in the strong coupling regime.
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Affiliation(s)
- Chang-Hua Liu
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - In Soo Kim
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Lincoln J Lauhon
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
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2110
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Zhou J, Zeng Q, Lv D, Sun L, Niu L, Fu W, Liu F, Shen Z, Jin C, Liu Z. Controlled Synthesis of High-Quality Monolayered α-In2Se3 via Physical Vapor Deposition. Nano Lett 2015; 15:6400-6405. [PMID: 26360543 DOI: 10.1021/acs.nanolett.5b01590] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In this work, we have demonstrated the synthesis of high-quality monolayered α-In2Se3 using physical vapor deposition method under atmospheric pressure. The quality of the In2Se3 atomic layers has been confirmed by complementary characterization technologies such as Raman/photoluminescence spectroscopies and atomic force microscope. The atomically resolved images have been obtained by the annular dark-field scanning transmission electron microscope. The field-effect transistors have been fabricated using the atomically layered In2Se3 and exhibit p-type semiconducting behaviors with the mobility up to 2.5 cm(2)/ Vs. The In2Se3 layers also show a good photoresponsivity of 340A/W, as well as 6 ms response time for the rise and 12 ms for the fall. These results make In2Se3 atomic layers a promising candidate for the optoelectronic and photosensitive device applications.
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Affiliation(s)
- Jiadong Zhou
- School of Materials Science and Engineering, Nanyang Technological University , 639798, Singapore
| | - Qingsheng Zeng
- School of Materials Science and Engineering, Nanyang Technological University , 639798, Singapore
| | - Danhui Lv
- State Key Laboratory of Silicon Materials, and School of Material Science & Engineering, Zhejiang University , Hangzhou, Zhejiang 310027, China
| | - Linfeng Sun
- Centre for Disruptive Photonic Technologies, School of Physical and Mathematical Sciences, Nanyang Technological University , 637371, Singapore
| | - Lin Niu
- School of Materials Science and Engineering, Nanyang Technological University , 639798, Singapore
| | - Wei Fu
- School of Materials Science and Engineering, Nanyang Technological University , 639798, Singapore
| | - Fucai Liu
- School of Materials Science and Engineering, Nanyang Technological University , 639798, Singapore
| | - Zexiang Shen
- School of Materials Science and Engineering, Nanyang Technological University , 639798, Singapore
- Centre for Disruptive Photonic Technologies, School of Physical and Mathematical Sciences, Nanyang Technological University , 637371, Singapore
| | - Chuanhong Jin
- State Key Laboratory of Silicon Materials, and School of Material Science & Engineering, Zhejiang University , Hangzhou, Zhejiang 310027, China
| | - Zheng Liu
- School of Materials Science and Engineering, Nanyang Technological University , 639798, Singapore
- NOVITAS, Nanoelectronics Centre of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University , 639798, Singapore
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2111
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Steinhoff A, Kim JH, Jahnke F, Rösner M, Kim DS, Lee C, Han GH, Jeong MS, Wehling TO, Gies C. Efficient Excitonic Photoluminescence in Direct and Indirect Band Gap Monolayer MoS2. Nano Lett 2015; 15:6841-7. [PMID: 26322814 DOI: 10.1021/acs.nanolett.5b02719] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We discuss the photoluminescence (PL) of semiconducting transition metal dichalcogenides on the basis of experiments and a microscopic theory. The latter connects ab initio calculations of the single-particle states and Coulomb matrix elements with a many-body description of optical emission spectra. For monolayer MoS2, we study the PL efficiency at the excitonic A and B transitions in terms of carrier populations in the band structure and provide a quantitative comparison to an (In)GaAs quantum well-structure. Suppression and enhancement of PL under biaxial strain is quantified in terms of changes in the local extrema of the conduction and valence bands. The large exciton binding energy in MoS2 enables two distinctly different excitation methods: above-band gap excitation and quasi-resonant excitation of excitonic resonances below the single-particle band gap. The latter case creates a nonequilibrium distribution of carriers predominantly in the K-valleys, which leads to strong emission from the A-exciton transition and a visible B-peak even if the band gap is indirect. For above-band gap excitation, we predict a strongly reduced emission intensity at comparable carrier densities and the absence of B-exciton emission. The results agree well with PL measurements performed on monolayer MoS2 at excitation wavelengths of 405 nm (above) and 532 nm (below the band gap).
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Affiliation(s)
- A Steinhoff
- Institut für Theoretische Physik, Universität Bremen , P.O. Box 330 440, 28334 Bremen, Germany
| | - J-H Kim
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 440-746, Republic of Korea
| | - F Jahnke
- Institut für Theoretische Physik, Universität Bremen , P.O. Box 330 440, 28334 Bremen, Germany
| | - M Rösner
- Institut für Theoretische Physik, Universität Bremen , P.O. Box 330 440, 28334 Bremen, Germany
- Bremen Center for Computational Materials Science, Universität Bremen , 28334 Bremen, Germany
| | - D-S Kim
- Department of Energy Science, Sungkyunkwan University , Suwon 440-746, Republic of Korea
| | - C Lee
- Department of Energy Science, Sungkyunkwan University , Suwon 440-746, Republic of Korea
| | - G H Han
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 440-746, Republic of Korea
| | - M S Jeong
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 440-746, Republic of Korea
- Department of Energy Science, Sungkyunkwan University , Suwon 440-746, Republic of Korea
| | - T O Wehling
- Institut für Theoretische Physik, Universität Bremen , P.O. Box 330 440, 28334 Bremen, Germany
- Bremen Center for Computational Materials Science, Universität Bremen , 28334 Bremen, Germany
| | - C Gies
- Institut für Theoretische Physik, Universität Bremen , P.O. Box 330 440, 28334 Bremen, Germany
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2112
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Woomer AH, Farnsworth TW, Hu J, Wells RA, Donley CL, Warren SC. Phosphorene: Synthesis, Scale-Up, and Quantitative Optical Spectroscopy. ACS Nano 2015; 9:8869-84. [PMID: 26256770 DOI: 10.1021/acsnano.5b02599] [Citation(s) in RCA: 203] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Phosphorene, a two-dimensional (2D) monolayer of black phosphorus, has attracted considerable theoretical interest, although the experimental realization of monolayer, bilayer, and few-layer flakes has been a significant challenge. Here, we systematically survey conditions for liquid exfoliation to achieve the first large-scale production of monolayer, bilayer, and few-layer phosphorus, with exfoliation demonstrated at the 10 g scale. We describe a rapid approach for quantifying the thickness of 2D phosphorus and show that monolayer and few-layer flakes produced by our approach are crystalline and unoxidized, while air exposure leads to rapid oxidation and the production of acid. With large quantities of 2D phosphorus now available, we perform the first quantitative measurements of the material's absorption edge-which is nearly identical to the material's band gap under our experimental conditions-as a function of flake thickness. Our interpretation of the absorbance spectrum relies on an analytical method introduced in this work, allowing the accurate determination of the absorption edge in polydisperse samples of quantum-confined semiconductors. Using this method, we found that the band gap of black phosphorus increased from 0.33 ± 0.02 eV in bulk to 1.88 ± 0.24 eV in bilayers, a range that is larger than that of any other 2D material. In addition, we quantified a higher-energy optical transition (VB-1 to CB), which changes from 2.0 eV in bulk to 3.23 eV in bilayers. This work describes several methods for producing and analyzing 2D phosphorus while also yielding a class of 2D materials with unprecedented optoelectronic properties.
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Affiliation(s)
- Adam H Woomer
- Department of Chemistry, ‡Chapel Hill Analytical and Nanofabrication Laboratory, and §Department of Applied Physical Sciences, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States
| | - Tyler W Farnsworth
- Department of Chemistry, ‡Chapel Hill Analytical and Nanofabrication Laboratory, and §Department of Applied Physical Sciences, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States
| | - Jun Hu
- Department of Chemistry, ‡Chapel Hill Analytical and Nanofabrication Laboratory, and §Department of Applied Physical Sciences, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States
| | - Rebekah A Wells
- Department of Chemistry, ‡Chapel Hill Analytical and Nanofabrication Laboratory, and §Department of Applied Physical Sciences, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States
| | - Carrie L Donley
- Department of Chemistry, ‡Chapel Hill Analytical and Nanofabrication Laboratory, and §Department of Applied Physical Sciences, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States
| | - Scott C Warren
- Department of Chemistry, ‡Chapel Hill Analytical and Nanofabrication Laboratory, and §Department of Applied Physical Sciences, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States
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2113
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Nayak AP, Yuan Z, Cao B, Liu J, Wu J, Moran ST, Li T, Akinwande D, Jin C, Lin JF. Pressure-Modulated Conductivity, Carrier Density, and Mobility of Multilayered Tungsten Disulfide. ACS Nano 2015; 9:9117-9123. [PMID: 26258661 DOI: 10.1021/acsnano.5b03295] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Tungsten disulfide (WS2) is a layered transition metal dichalcogenide (TMD) that differs from other two-dimensional (2D) compounds such as graphene due to its unique semiconducting, tunable-band-gap nature. Multilayered WS2 exhibits an indirect band gap Eg of ∼1.3 eV, along with a higher load-bearing ability that is promising for strain-tuning device applications, but the electronic properties of multilayered WS2 at higher strain conditions (i.e., static strain >12%) remain an open question. Here we have studied the structural, electronic, electrical, and vibrational properties of multilayered WS2 at hydrostatic pressures up to ∼35 GPa experimentally in a diamond anvil cell and theoretically using first-principles ab initio calculations. Our results show that WS2 undergoes an isostructural semiconductor-to-metallic (S-M) transition at approximately 22 GPa at 280 K, which arises from the overlap of the highest valence and lowest conduction bands. The S-M transition is caused by increased sulfur-sulfur interactions as the interlayer spacing decreases with applied hydrostatic pressure. The metalization in WS2 can be alternatively interpreted as a 2D to 3D (three-dimensional) phase transition that is associated with a substantial modulation of the charge carrier characteristics including a 6-order decrease in resistivity, a 2-order decrease in mobility, and a 4-order increase in carrier concentration. These distinct pressure-tunable characteristics of the dimensionalized WS2 differentiate it from other TMD compounds such as MoS2 and promise future developments in strain-modulated advanced devices.
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Affiliation(s)
| | - Zhen Yuan
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Collaborative Innovation Center of Quantum Matt , Beijing 100190, China
| | - Boxiao Cao
- Department of Civil and Environmental Engineering, Computational Materials Science Group, George Washington University , 20052, Washington, D.C., United States
| | | | - Junjie Wu
- Center for High Pressure Science and Advanced Technology Research (HPSTAR) , Shanghai 201900, China
| | | | - Tianshu Li
- Department of Civil and Environmental Engineering, Computational Materials Science Group, George Washington University , 20052, Washington, D.C., United States
| | | | - Changqing Jin
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Collaborative Innovation Center of Quantum Matt , Beijing 100190, China
| | - Jung-Fu Lin
- Center for High Pressure Science and Advanced Technology Research (HPSTAR) , Shanghai 201900, China
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2114
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Li Y, Wang W, Xia K, Zhang W, Jiang Y, Zeng Y, Zhang H, Jin C, Zhang Z, Yang D. Ultrathin Two-Dimensional Pd-Based Nanorings as Catalysts for Hydrogenation with High Activity and Stability. Small 2015; 11:4745-52. [PMID: 26150015 DOI: 10.1002/smll.201500769] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Revised: 06/01/2015] [Indexed: 05/25/2023]
Abstract
Despite a few reports on the synthesis of ultrathin 2D nanosheets made of noble metals, it still remains a tremendous challenge to generate their ultrathin hollowed nanostructures, which are of particular interest in highly active catalysis due to their unique structural features. Here, the synthesis of ultrathin 2D Pd nanorings is reported with a hollow interior by selective epitaxial growth of Pd atoms on the periphery of the as-preformed Pd nanosheets in combination with oxidative etching. This approach can be extended to fabricate Pd-based bimetallic ultrathin nanorings such as Pd-Pt. The Pd nanorings exhibit substantially enhanced activity toward the hydrogenation of p-nitrophenol, which is 2.2 and 33.4 times higher than that of the Pd nanosheets and commercial Pd black, respectively. Significantly, the Pd nanorings are highly stable with only less than 11% loss in activity compared to 45.7% loss of the Pd nanosheets and 72.2% loss of the Pd black after ten cycles.
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Affiliation(s)
- Yi Li
- State Key Laboratory of Silicon Materials, School of Materials Science and Engineering and Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou, Zhejiang, 310027, P. R. China
| | - Wenxing Wang
- State Key Laboratory of Silicon Materials, School of Materials Science and Engineering and Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou, Zhejiang, 310027, P. R. China
| | - Kaiyang Xia
- State Key Laboratory of Silicon Materials, School of Materials Science and Engineering and Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou, Zhejiang, 310027, P. R. China
| | - Wenjun Zhang
- State Key Laboratory of Silicon Materials, School of Materials Science and Engineering and Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou, Zhejiang, 310027, P. R. China
| | - Yingying Jiang
- State Key Laboratory of Silicon Materials, School of Materials Science and Engineering and Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou, Zhejiang, 310027, P. R. China
| | - Yuewu Zeng
- State Key Laboratory of Silicon Materials, School of Materials Science and Engineering and Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou, Zhejiang, 310027, P. R. China
| | - Hui Zhang
- State Key Laboratory of Silicon Materials, School of Materials Science and Engineering and Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou, Zhejiang, 310027, P. R. China
| | - Chuanhong Jin
- State Key Laboratory of Silicon Materials, School of Materials Science and Engineering and Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou, Zhejiang, 310027, P. R. China
| | - Ze Zhang
- State Key Laboratory of Silicon Materials, School of Materials Science and Engineering and Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou, Zhejiang, 310027, P. R. China
| | - Deren Yang
- State Key Laboratory of Silicon Materials, School of Materials Science and Engineering and Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou, Zhejiang, 310027, P. R. China
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2115
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Abstract
The liquid-phase exfoliation of phosphorene, the two-dimensional derivative of black phosphorus, in the solvents dimethyl sulfoxide (DMSO), dimethylformamide (DMF), isopropyl alcohol, N-methyl-2-pyrrolidone, and N-cyclohexyl-2-pyrrolidone is investigated using three molecular-scale "computer experiments". We modeled solvent-phosphorene interactions using an atomistic force field, based on ab initio calculations and lattice dynamics, that accurately reproduces experimental mechanical properties. We probed solvent molecule ordering at phosphorene/solvent interfaces and discovered that planar molecules such as N-methyl-2-pyrrolidone preferentially orient parallel to the interface. We subsequently measured the energy required to peel a single phosphorene monolayer from a stack of black phosphorus and analyzed the role of "wedges" of solvent molecules intercalating between phosphorene sheets in initiating exfoliation. The exfoliation efficacy of a solvent is enhanced when either molecular planarity "sharpens" this molecular wedge or strong phosphorene-solvent adhesion stabilizes the newly exposed phosphorene surfaces. Finally, we examined the colloidal stability of exfoliated flakes by simulating their aggregation and showed that dispersion is favored when the cohesive energy between the molecules in the solvent monolayer confined between the phosphorene sheets is high (as with DMSO) and is hindered when the adhesion between these molecules and phosphorene is strong; the molecular planarity in solvents like DMF enhances the cohesive energy. Our results are consistent with, and provide a molecular context for, experimental exfoliation studies of phosphorene and other layered solids, and our molecular insights into the significant role of solvent molecular geometry and ordering should complement prevalent solubility-parameter-based approaches in establishing design rules for effective nanomaterial exfoliation media.
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Affiliation(s)
- Vishnu Sresht
- Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Agílio A H Pádua
- Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
- Institut de Chimie de Clermont-Ferrand, Université Blaise Pascal and CNRS , 63171 Aubiére, France
| | - Daniel Blankschtein
- Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
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2116
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Keyshar K, Gong Y, Ye G, Brunetto G, Zhou W, Cole DP, Hackenberg K, He Y, Machado L, Kabbani M, Hart AHC, Li B, Galvao DS, George A, Vajtai R, Tiwary CS, Ajayan PM. Chemical Vapor Deposition of Monolayer Rhenium Disulfide (ReS2). Adv Mater 2015; 27:4640-4648. [PMID: 26140355 DOI: 10.1002/adma.201501795] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 05/16/2015] [Indexed: 06/04/2023]
Abstract
The direct synthesis of monolayer and multilayer ReS2 by chemical vapor deposition at a low temperature of 450 °C is reported. Detailed characterization of this material is performed using various spectroscopy and microscopy methods. Furthermore initial field-effect transistor characteristics are evaluated, which highlight the potential in being used as an n-type semiconductor.
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Affiliation(s)
- Kunttal Keyshar
- Department of Materials Science and Nanoengineering, Rice University, Houston, TX, 77005, USA
| | - Yongji Gong
- Department of Chemistry, Rice University, Houston, TX, 77005, USA
| | - Gonglan Ye
- Department of Materials Science and Nanoengineering, Rice University, Houston, TX, 77005, USA
| | - Gustavo Brunetto
- Applied Physics Department, State University of Campinas - UNICAMP, UNICAMP-IFGW-DFA, 13083-859, Campinas, SP, Brazil
| | - Wu Zhou
- Materials Science and Technology Division, Oak Ridge National Lab, Oak Ridge, TN, 37831, USA
| | - Daniel P Cole
- U.S. Army Research Laboratory, Vehicle Technology Directorate, Aberdeen Proving Ground, MD, 21005, USA
| | - Ken Hackenberg
- Department of Materials Science and Nanoengineering, Rice University, Houston, TX, 77005, USA
| | - Yongmin He
- Department of Materials Science and Nanoengineering, Rice University, Houston, TX, 77005, USA
| | - Leonardo Machado
- Applied Physics Department, State University of Campinas - UNICAMP, UNICAMP-IFGW-DFA, 13083-859, Campinas, SP, Brazil
| | - Mohamad Kabbani
- Department of Materials Science and Nanoengineering, Rice University, Houston, TX, 77005, USA
| | - Amelia H C Hart
- Department of Materials Science and Nanoengineering, Rice University, Houston, TX, 77005, USA
| | - Bo Li
- Department of Materials Science and Nanoengineering, Rice University, Houston, TX, 77005, USA
| | - Douglas S Galvao
- Applied Physics Department, State University of Campinas - UNICAMP, UNICAMP-IFGW-DFA, 13083-859, Campinas, SP, Brazil
| | - Antony George
- Department of Materials Science and Nanoengineering, Rice University, Houston, TX, 77005, USA
| | - Robert Vajtai
- Department of Materials Science and Nanoengineering, Rice University, Houston, TX, 77005, USA
| | - Chandra Sekhar Tiwary
- Department of Materials Science and Nanoengineering, Rice University, Houston, TX, 77005, USA
| | - Pulickel M Ajayan
- Department of Materials Science and Nanoengineering, Rice University, Houston, TX, 77005, USA
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2117
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Liu Y, Tan C, Chou H, Nayak A, Wu D, Ghosh R, Chang HY, Hao Y, Wang X, Kim JS, Piner R, Ruoff RS, Akinwande D, Lai K. Thermal Oxidation of WSe2 Nanosheets Adhered on SiO2/Si Substrates. Nano Lett 2015; 15:4979-84. [PMID: 26171759 DOI: 10.1021/acs.nanolett.5b02069] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Because of the drastically different intralayer versus interlayer bonding strengths, the mechanical, thermal, and electrical properties of two-dimensional (2D) materials are highly anisotropic between the in-plane and out-of-plane directions. The structural anisotropy may also play a role in chemical reactions, such as oxidation, reduction, and etching. Here, the composition, structure, and electrical properties of mechanically exfoliated WSe2 nanosheets on SiO2/Si substrates were studied as a function of the extent of thermal oxidation. A major component of the oxidation, as indicated from optical and Raman data, starts from the nanosheet edges and propagates laterally toward the center. Partial oxidation also occurs in certain areas at the surface of the flakes, which are shown to be highly conductive by microwave impedance microscopy. Using secondary ion mass spectroscopy, we also observed extensive oxidation at the WSe2-SiO2 interface. The combination of multiple microcopy methods can thus provide vital information on the spatial evolution of chemical reactions on 2D materials and the nanoscale electrical properties of the reaction products.
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Affiliation(s)
- Yingnan Liu
- †Department of Physics, University of Texas at Austin, Austin, Texas 78712, United States
| | - Cheng Tan
- ‡Microelectronics Research Center, University of Texas at Austin, Austin, Texas 78758, United States
- §Department of Mechanical Engineering and the Materials Science and Engineering Program, University of Texas at Austin, Austin, Texas 78712, United States
| | - Harry Chou
- §Department of Mechanical Engineering and the Materials Science and Engineering Program, University of Texas at Austin, Austin, Texas 78712, United States
| | - Avinash Nayak
- ‡Microelectronics Research Center, University of Texas at Austin, Austin, Texas 78758, United States
| | - Di Wu
- †Department of Physics, University of Texas at Austin, Austin, Texas 78712, United States
| | - Rudresh Ghosh
- §Department of Mechanical Engineering and the Materials Science and Engineering Program, University of Texas at Austin, Austin, Texas 78712, United States
| | - Hsiao-Yu Chang
- ‡Microelectronics Research Center, University of Texas at Austin, Austin, Texas 78758, United States
| | - Yufeng Hao
- §Department of Mechanical Engineering and the Materials Science and Engineering Program, University of Texas at Austin, Austin, Texas 78712, United States
| | - Xiaohan Wang
- §Department of Mechanical Engineering and the Materials Science and Engineering Program, University of Texas at Austin, Austin, Texas 78712, United States
| | - Joon-Seok Kim
- ‡Microelectronics Research Center, University of Texas at Austin, Austin, Texas 78758, United States
| | - Richard Piner
- §Department of Mechanical Engineering and the Materials Science and Engineering Program, University of Texas at Austin, Austin, Texas 78712, United States
| | - Rodney S Ruoff
- §Department of Mechanical Engineering and the Materials Science and Engineering Program, University of Texas at Austin, Austin, Texas 78712, United States
- ∥Center for Multidimensional Carbon Materials, Institute for Basic Science (IBS), Ulsan 689-798, Republic of Korea
- ⊥Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, Republic of Korea
| | - Deji Akinwande
- ‡Microelectronics Research Center, University of Texas at Austin, Austin, Texas 78758, United States
| | - Keji Lai
- †Department of Physics, University of Texas at Austin, Austin, Texas 78712, United States
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2118
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Beyer A, Vieker H, Klett R, Meyer zu Theenhausen H, Angelova P, Gölzhäuser A. Imaging of carbon nanomembranes with helium ion microscopy. Beilstein J Nanotechnol 2015; 6:1712-1720. [PMID: 26425423 PMCID: PMC4578422 DOI: 10.3762/bjnano.6.175] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 07/16/2015] [Indexed: 06/02/2023]
Abstract
Carbon nanomembranes (CNMs) prepared from aromatic self-assembled monolayers constitute a recently developed class of 2D materials. They are made by a combination of self-assembly, radiation-induced cross-linking and the detachment of the cross-linked SAM from its substrate. CNMs can be deposited on arbitrary substrates, including holey and perforated ones, as well as on metallic (transmission electron microscopy) grids. Therewith, freestanding membranes with a thickness of 1 nm and macroscopic lateral dimensions can be prepared. Although free-standing CNMs cannot be imaged by light microscopy, charged particle techniques can visualize them. However, CNMs are electrically insulating, which makes them sensitive to charging. We demonstrate that the helium ion microscope (HIM) is a good candidate for imaging freestanding CNMs due to its efficient charge compensation tool. Scanning with a beam of helium ions while recording the emitted secondary electrons generates the HIM images. The advantages of HIM are high resolution, high surface sensitivity and large depth of field. The effects of sample charging, imaging of multilayer CNMs as well as imaging artefacts are discussed.
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Affiliation(s)
- André Beyer
- Physics of Supramolecular Systems and Surfaces, Bielefeld University, 33615 Bielefeld, Germany
| | | | - Robin Klett
- Physics of Supramolecular Systems and Surfaces, Bielefeld University, 33615 Bielefeld, Germany
| | | | | | - Armin Gölzhäuser
- Physics of Supramolecular Systems and Surfaces, Bielefeld University, 33615 Bielefeld, Germany
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2119
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Rigosi AF, Hill HM, Li Y, Chernikov A, Heinz TF. Probing Interlayer Interactions in Transition Metal Dichalcogenide Heterostructures by Optical Spectroscopy: MoS2/WS2 and MoSe2/WSe2. Nano Lett 2015; 15:5033-8. [PMID: 26186085 DOI: 10.1021/acs.nanolett.5b01055] [Citation(s) in RCA: 136] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
We have applied optical absorption spectroscopy to investigate van der Waals heterostructures formed of pairs of monolayer transition metal dichalcogenide crystals, choosing MoS2/WS2 and MoSe2/WSe2 as test cases. In the heterostructure spectra, we observe a significant broadening of the excitonic transitions compared to the corresponding features in the isolated layers. The broadening is interpreted as a lifetime effect arising from decay of excitons initially created in either layer through charge transfer processes expected for a staggered band alignment. The measured spectral broadening of 20 meV - 35 meV implies lifetimes for charge separation of the near band-edge A and B excitons in the range of 20-35 fs. Higher-lying transitions exhibit still greater broadening.
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Affiliation(s)
- Albert F Rigosi
- Departments of Physics and Electrical Engineering, Columbia University, New York, New York 10027, United States
| | - Heather M Hill
- Departments of Physics and Electrical Engineering, Columbia University, New York, New York 10027, United States
| | - Yilei Li
- Departments of Physics and Electrical Engineering, Columbia University, New York, New York 10027, United States
| | - Alexey Chernikov
- Departments of Physics and Electrical Engineering, Columbia University, New York, New York 10027, United States
| | - Tony F Heinz
- Departments of Physics and Electrical Engineering, Columbia University, New York, New York 10027, United States
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2120
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Waduge P, Bilgin I, Larkin J, Henley RY, Goodfellow K, Graham AC, Bell DC, Vamivakas N, Kar S, Wanunu M. Direct and Scalable Deposition of Atomically Thin Low-Noise MoS2 Membranes on Apertures. ACS Nano 2015; 9:7352-9. [PMID: 26111109 PMCID: PMC5142633 DOI: 10.1021/acsnano.5b02369] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Molybdenum disulfide (MoS2) flakes can grow beyond the edge of an underlying substrate into a planar freestanding crystal. When the substrate edge is in the form of an aperture, reagent-limited nucleation followed by edge growth facilitate direct and selective growth of freestanding MoS2 membranes. We have found conditions under which MoS2 grows preferentially across micrometer-scale prefabricated solid-state apertures in silicon nitride membranes, resulting in sealed membranes that are one to a few atomic layers thick. We have investigated the structure and purity of our membranes by a combination of atomic-resolution transmission electron microscopy, elemental analysis, Raman spectroscopy, photoluminescence spectroscopy, and low-noise ion-current recordings through nanopores fabricated in such membranes. Finally, we demonstrate the utility of fabricated ultrathin nanopores in such membranes for single-stranded DNA translocation detection.
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Affiliation(s)
- Pradeep Waduge
- Department of Physics, Northeastern University, Boston, Massachusetts 02115, United States
| | - Ismail Bilgin
- Department of Physics, Northeastern University, Boston, Massachusetts 02115, United States
| | - Joseph Larkin
- Department of Physics, Northeastern University, Boston, Massachusetts 02115, United States
| | - Robert Y. Henley
- Department of Physics, Northeastern University, Boston, Massachusetts 02115, United States
| | - Kenneth Goodfellow
- The Institute of Optics, University of Rochester, Rochester, New York 14627, United States
| | - Adam C. Graham
- Center for Nanoscale Systems, Harvard University, Cambridge, Massachusetts 02138, United States
| | - David C. Bell
- Center for Nanoscale Systems, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Nick Vamivakas
- The Institute of Optics, University of Rochester, Rochester, New York 14627, United States
| | - Swastik Kar
- Department of Physics, Northeastern University, Boston, Massachusetts 02115, United States
- Address correspondence to ,
| | - Meni Wanunu
- Department of Physics, Northeastern University, Boston, Massachusetts 02115, United States
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
- Address correspondence to ,
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2121
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Duan J, Chen S, Chambers BA, Andersson GG, Qiao SZ. 3D WS2 Nanolayers@Heteroatom-Doped Graphene Films as Hydrogen Evolution Catalyst Electrodes. Adv Mater 2015; 27:4234-41. [PMID: 26061221 DOI: 10.1002/adma.201501692] [Citation(s) in RCA: 171] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 05/14/2015] [Indexed: 05/04/2023]
Affiliation(s)
- Jingjing Duan
- School of Chemical Engineering, The University of Adelaide, Adelaide, SA, 5005, Australia
| | - Sheng Chen
- School of Chemical Engineering, The University of Adelaide, Adelaide, SA, 5005, Australia
| | - Benjamin A Chambers
- School of Chemical and Physical Sciences, Flinders University, Adelaide, SA, 5001, Australia
| | - Gunther G Andersson
- School of Chemical and Physical Sciences, Flinders University, Adelaide, SA, 5001, Australia
| | - Shi Zhang Qiao
- School of Chemical Engineering, The University of Adelaide, Adelaide, SA, 5005, Australia
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2122
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Zhou KG, Zhang HL. Lighten the Olympia of the Flatland: Probing and Manipulating the Photonic Properties of 2D Transition-Metal Dichalcogenides. Small 2015; 11:3206-3220. [PMID: 25711142 DOI: 10.1002/smll.201403385] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 01/11/2014] [Indexed: 06/04/2023]
Abstract
Following the adventures of graphene, 2D transition metal dichalcogenides (TMDs) have recently seized part of the territory in the flatland. Branched by different components of metals and chalcogenides, the families of 2D TMDs have grown rapidly, in which the semiconductive ones have shown colorful photonic properties. By tuning the atomic components and reducing the thickness or planar size of the layers, one can manipulate the optical performance of 2D TMDs, e.g., the intensity, angular momentum, and frequency of the emitted light, or toward ultrafast nonlinear absorption. As a powerful optical method, the Raman characteristics of 2D TMDs have been successfully used to explore their lattices and electronic structures. Along with the maturing of 2D TMDs, their hybrids play an important role. The unique photonic properties of 2D van der Waals heterostructures and 2D alloys are introduced here. Apart from the group VI TMDs, future prospects are identified to harness the optical properties of other 2D TMDs and the related investigations of their hybrids are underway.
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Affiliation(s)
- Kai-Ge Zhou
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, P.R. China
- School of Chemistry, University of Manchester, Manchester, M13 9PL, UK
| | - Hao-Li Zhang
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, P.R. China
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2123
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Abstract
Vertical stacking of two-dimensional (2D) crystals, such as graphene and hexagonal boron nitride, has recently lead to a new class of materials known as van der Waals heterostructures (vdWHs) with unique and highly tunable electronic properties. Ab initio calculations should in principle provide a powerful tool for modeling and guiding the design of vdWHs, but in their traditional form such calculations are only feasible for commensurable structures with a few layers. Here we show that the dielectric properties of realistic, incommensurable vdWHs comprising hundreds of layers can be efficiently calculated using a multiscale approach where the dielectric functions of the individual layers (the dielectric building blocks) are computed ab initio and coupled together via the long-range Coulomb interaction. We use the method to illustrate the 2D-3D transition of the dielectric function of multilayer MoS2 crystals, the hybridization of quantum plasmons in thick graphene/hBN heterostructures, and to demonstrate the intricate effect of substrate screening on the non-Rydberg exciton series in supported WS2. The dielectric building blocks for a variety of 2D crystals are available in an open database together with the software for solving the coupled electrodynamic equations.
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Affiliation(s)
- Kirsten Andersen
- †Center for Atomic-scale Materials Design, Department of Physics, and ‡Center for Nanostructured Graphene, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Simone Latini
- †Center for Atomic-scale Materials Design, Department of Physics, and ‡Center for Nanostructured Graphene, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Kristian S Thygesen
- †Center for Atomic-scale Materials Design, Department of Physics, and ‡Center for Nanostructured Graphene, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
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2124
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Heo H, Sung JH, Jin G, Ahn JH, Kim K, Lee MJ, Cha S, Choi H, Jo MH. Rotation-misfit-free heteroepitaxial stacking and stitching growth of hexagonal transition-metal dichalcogenide monolayers by nucleation kinetics controls. Adv Mater 2015; 27:3803-10. [PMID: 26011695 DOI: 10.1002/adma.201500846] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 04/23/2015] [Indexed: 05/22/2023]
Abstract
2D vertical stacking and lateral stitching growth of monolayer (ML) hexagonal transition-metal dichalcogenides are reported. The 2D heteroepitaxial manipulation of MoS2 and WS2 MLs is achieved by control of the 2D nucleation kinetics during the sequential vapor-phase growth. It enables the creation of hexagon-on-hexagon unit-cell stacking and hexagon-by-hexagon stitching without interlayer rotation misfits.
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Affiliation(s)
- Hoseok Heo
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), 77 Cheongam-Ro, Pohang, 790-784, Korea
- Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), 77 Cheongam-Ro, Pohang, 790-784, Korea
| | - Ji Ho Sung
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), 77 Cheongam-Ro, Pohang, 790-784, Korea
- Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), 77 Cheongam-Ro, Pohang, 790-784, Korea
| | - Gangtae Jin
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), 77 Cheongam-Ro, Pohang, 790-784, Korea
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), 77 Cheongam-Ro, Pohang, 790-784, Korea
| | - Ji-Hoon Ahn
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), 77 Cheongam-Ro, Pohang, 790-784, Korea
| | - Kyungwook Kim
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), 77 Cheongam-Ro, Pohang, 790-784, Korea
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), 77 Cheongam-Ro, Pohang, 790-784, Korea
| | - Myoung-Jae Lee
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), 77 Cheongam-Ro, Pohang, 790-784, Korea
| | - Soonyoung Cha
- School of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 120-749, Korea
| | - Hyunyong Choi
- School of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 120-749, Korea
| | - Moon-Ho Jo
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), 77 Cheongam-Ro, Pohang, 790-784, Korea
- Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), 77 Cheongam-Ro, Pohang, 790-784, Korea
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), 77 Cheongam-Ro, Pohang, 790-784, Korea
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2125
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Liu H, Zheng H, Yang F, Jiao L, Chen J, Ho W, Gao C, Jia J, Xie M. Line and Point Defects in MoSe2 Bilayer Studied by Scanning Tunneling Microscopy and Spectroscopy. ACS Nano 2015; 9:6619-6625. [PMID: 26051223 DOI: 10.1021/acsnano.5b02789] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Bilayer (BL) MoSe2 films grown by molecular-beam epitaxy (MBE) are studied by scanning tunneling microscopy and spectroscopy (STM/S). Similar to monolayer (ML) films, networks of inversion domain boundary (DB) defects are observed both in the top and bottom layers of BL MoSe2, and often they are seen spatially correlated such that one is on top of the other. There are also isolated ones in the bottom layer without companion in the top-layer and are detected by STM/S through quantum tunneling of the defect states through the barrier of the MoSe2 ML. Comparing the DB states in BL MoSe2 with that of ML film reveals some common features as well as differences. Quantum confinement of the defect states is indicated. Point defects in BL MoSe2 are also observed by STM/S, where ionization of the donor defect by the tip-induced electric field is evidenced. These results are of great fundamental interests as well as practical relevance of devices made of MoSe2 ultrathin layers.
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Affiliation(s)
- Hongjun Liu
- †Physics Department, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Hao Zheng
- †Physics Department, The University of Hong Kong, Pokfulam Road, Hong Kong, China
- ‡Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, China
- §Collaborative Innovation Center of Advanced Microstructures, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
| | - Fang Yang
- ‡Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Lu Jiao
- †Physics Department, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Jinglei Chen
- †Physics Department, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Wingkin Ho
- †Physics Department, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Chunlei Gao
- ‡Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, China
- §Collaborative Innovation Center of Advanced Microstructures, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
| | - Jinfeng Jia
- ‡Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, China
- §Collaborative Innovation Center of Advanced Microstructures, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
| | - Maohai Xie
- †Physics Department, The University of Hong Kong, Pokfulam Road, Hong Kong, China
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2126
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Wang G, Pandey R, Karna SP. Atomically thin group v elemental films: theoretical investigations of antimonene allotropes. ACS Appl Mater Interfaces 2015; 7:11490-11496. [PMID: 25955131 DOI: 10.1021/acsami.5b02441] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Group V elemental monolayers including phosphorene are emerging as promising 2D materials with semiconducting electronic properties. Here, we present the results of first-principles calculations on stability, mechanical and electronic properties of 2D antimony (Sb), antimonene. Our calculations show that free-standing α and β allotropes of antimonene are stable and semiconducting. The α-Sb has a puckered structure with two atomic sublayers and β-Sb has a buckled hexagonal lattice. The calculated Raman spectra and STM images have distinct features thus facilitating characterization of both allotropes. The β-Sb has nearly isotropic mechanical properties, whereas α-Sb shows strongly anisotropic characteristics. An indirect-direct band gap transition is expected with moderate tensile strains applied to the monolayers, which opens up the possibility of their applications in optoelectronics.
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Affiliation(s)
- Gaoxue Wang
- †Department of Physics, Michigan Technological University, Houghton, Michigan 49931, United States
| | - Ravindra Pandey
- †Department of Physics, Michigan Technological University, Houghton, Michigan 49931, United States
| | - Shashi P Karna
- ‡U.S. Army Research Laboratory, Weapons and Materials Research Directorate, Aberdeen Proving Ground, Maryland 21005-5069, United States
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2127
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Chen B, Sahin H, Suslu A, Ding L, Bertoni MI, Peeters FM, Tongay S. Environmental Changes in MoTe2 Excitonic Dynamics by Defects-Activated Molecular Interaction. ACS Nano 2015; 9:5326-5332. [PMID: 25868985 DOI: 10.1021/acsnano.5b00985] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Monolayers of group VI transition metal dichalcogenides possess direct gaps in the visible spectrum with the exception of MoTe2, where its gap is suitably located in the infrared region but its stability is of particular interest, as tellurium compounds are acutely sensitive to oxygen exposure. Here, our environmental (time-dependent) measurements reveal two distinct effects on MoTe2 monolayers: For weakly luminescent monolayers, photoluminescence signal and optical contrast disappear, as if they are decomposed, but yet remain intact as evidenced by AFM and Raman measurements. In contrast, strongly luminescent monolayers retain their optical contrast for a prolonged amount of time, while their PL peak blue-shifts and PL intensity saturates to slightly lower values. Our X-ray photoelectron spectroscopy measurements and DFT calculations suggest that the presence of defects and functionalization of these defect sites with O2 molecules strongly dictate their material properties and aging response by changing the excitonic dynamics due to deep or shallow states that are created within the optical band gap. Presented results not only shed light on environmental effects on fundamental material properties and excitonic dynamics of MoTe2 monolayers but also highlight striking material transformation for metastable 2D systems such as WTe2, silicone, and phosphorene.
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Affiliation(s)
| | - Hasan Sahin
- ‡Department of Physics, University of Antwerp, Groenenborgerlaan 171, Antwerpen B-2020, Belgium
| | | | | | | | - F M Peeters
- ‡Department of Physics, University of Antwerp, Groenenborgerlaan 171, Antwerpen B-2020, Belgium
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2128
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Worsley MA, Shin SJ, Merrill MD, Lenhardt J, Nelson AJ, Woo LY, Gash AE, Baumann TF, Orme CA. Ultralow Density, Monolithic WS2, MoS2, and MoS2/Graphene Aerogels. ACS Nano 2015; 9:4698-705. [PMID: 25858296 DOI: 10.1021/acsnano.5b00087] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We describe the synthesis and characterization of monolithic, ultralow density WS2 and MoS2 aerogels, as well as a high surface area MoS2/graphene hybrid aerogel. The monolithic WS2 and MoS2 aerogels are prepared via thermal decomposition of freeze-dried ammonium thio-molybdate (ATM) and ammonium thio-tungstate (ATT) solutions, respectively. The densities of the pure dichalcogenide aerogels represent 0.4% and 0.5% of full density MoS2 and WS2, respectively, and can be tailored by simply changing the initial ATM or ATT concentrations. Similar processing in the presence of the graphene aerogel results in a hybrid structure with MoS2 sheets conformally coating the graphene scaffold. This layered motif produces a ∼50 wt % MoS2 aerogel with BET surface area of ∼700 m(2)/g and an electrical conductivity of 112 S/m. The MoS2/graphene aerogel shows promising results as a hydrogen evolution reaction catalyst with low onset potential (∼100 mV) and high current density (100 mA/cm(2) at 260 mV).
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Affiliation(s)
- Marcus A Worsley
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - Swanee J Shin
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - Matthew D Merrill
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - Jeremy Lenhardt
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - Art J Nelson
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - Leta Y Woo
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - Alex E Gash
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - Theodore F Baumann
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - Christine A Orme
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
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2129
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Campbell PM, Tarasov A, Joiner CA, Ready WJ, Vogel EM. Enhanced Resonant Tunneling in Symmetric 2D Semiconductor Vertical Heterostructure Transistors. ACS Nano 2015; 9:5000-5008. [PMID: 25923194 DOI: 10.1021/nn507174c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Tunneling transistors with negative differential resistance have widespread appeal for both digital and analog electronics. However, most attempts to demonstrate resonant tunneling devices, including graphene-insulator-graphene structures, have resulted in low peak-to-valley ratios, limiting their application. We theoretically demonstrate that vertical heterostructures consisting of two identical monolayer 2D transition-metal dichalcogenide semiconductor electrodes and a hexagonal boron nitride barrier result in a peak-to-valley ratio several orders of magnitude higher than the best that can be achieved using graphene electrodes. The peak-to-valley ratio is large even at coherence lengths on the order of a few nanometers, making these devices appealing for nanoscale electronics.
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Affiliation(s)
- Philip M Campbell
- †School of Materials Science and Engineering and ‡Georgia Tech Research Institute, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Alexey Tarasov
- †School of Materials Science and Engineering and ‡Georgia Tech Research Institute, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Corey A Joiner
- †School of Materials Science and Engineering and ‡Georgia Tech Research Institute, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - William J Ready
- †School of Materials Science and Engineering and ‡Georgia Tech Research Institute, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Eric M Vogel
- †School of Materials Science and Engineering and ‡Georgia Tech Research Institute, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
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2130
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Sarkar D, Xie X, Kang J, Zhang H, Liu W, Navarrete J, Moskovits M, Banerjee K. Functionalization of transition metal dichalcogenides with metallic nanoparticles: implications for doping and gas-sensing. Nano Lett 2015; 15:2852-62. [PMID: 25723363 DOI: 10.1021/nl504454u] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Transition metal dichalcogenides (TMDs), belonging to the class of two-dimensional (2D) layered materials, have instigated a lot of interest in diverse application fields due to their unique electrical, mechanical, magnetic, and optical properties. Tuning the electrical properties of TMDs through charge transfer or doping is necessary for various optoelectronic applications. This paper presents the experimental investigation of the doping effect on TMDs, mainly focusing on molybdenum disulfide (MoS2), by metallic nanoparticles (NPs), exploring noble metals such as silver (Ag), palladium (Pd), and platinum (Pt) as well as the low workfunction metals such as scandium (Sc) and yttrium (Y) for the first time. The dependence of the doping behavior of MoS2 on the metal workfunction is demonstrated and it is shown that Pt nanoparticles can lead to as large as 137 V shift in threshold voltage of a back-gated monolayered MoS2 FET. Variation of the MoS2 FET transfer curves with the increase in the dose of NPs as well as the effect of the number of MoS2 layers on the doping characteristics are also discussed for the first time. Moreover, the doping effect on WSe2 is studied with the first demonstration of p-type doping using Pt NPs. Apart from doping, the use of metallic NP functionalized TMDs for gas sensing application is also demonstrated.
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Affiliation(s)
- Deblina Sarkar
- †Department of Electrical and Computer Engineering and ‡Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Xuejun Xie
- †Department of Electrical and Computer Engineering and ‡Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Jiahao Kang
- †Department of Electrical and Computer Engineering and ‡Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Haojun Zhang
- †Department of Electrical and Computer Engineering and ‡Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Wei Liu
- †Department of Electrical and Computer Engineering and ‡Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Jose Navarrete
- †Department of Electrical and Computer Engineering and ‡Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Martin Moskovits
- †Department of Electrical and Computer Engineering and ‡Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Kaustav Banerjee
- †Department of Electrical and Computer Engineering and ‡Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
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2131
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Feng J, Liu K, Graf M, Lihter M, Bulushev RD, Dumcenco D, Alexander DTL, Krasnozhon D, Vuletic T, Kis A, Radenovic A. Electrochemical Reaction in Single Layer MoS2: Nanopores Opened Atom by Atom. Nano Lett 2015; 15:3431-8. [PMID: 25928894 DOI: 10.1021/acs.nanolett.5b00768] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Ultrathin nanopore membranes based on 2D materials have demonstrated ultimate resolution toward DNA sequencing. Among them, molybdenum disulfide (MoS2) shows long-term stability as well as superior sensitivity enabling high throughput performance. The traditional method of fabricating nanopores with nanometer precision is based on the use of focused electron beams in transmission electron microscope (TEM). This nanopore fabrication process is time-consuming, expensive, not scalable, and hard to control below 1 nm. Here, we exploited the electrochemical activity of MoS2 and developed a convenient and scalable method to controllably make nanopores in single-layer MoS2 with subnanometer precision using electrochemical reaction (ECR). The electrochemical reaction on the surface of single-layer MoS2 is initiated at the location of defects or single atom vacancy, followed by the successive removals of individual atoms or unit cells from single-layer MoS2 lattice and finally formation of a nanopore. Step-like features in the ionic current through the growing nanopore provide direct feedback on the nanopore size inferred from a widely used conductance vs pore size model. Furthermore, DNA translocations can be detected in situ when as-fabricated MoS2 nanopores are used. The atomic resolution and accessibility of this approach paves the way for mass production of nanopores in 2D membranes for potential solid-state nanopore sequencing.
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Affiliation(s)
- J Feng
- †Laboratory of Nanoscale Biology, Institute of Bioengineering, School of Engineering, EPFL, 1015 Lausanne, Switzerland
| | - K Liu
- †Laboratory of Nanoscale Biology, Institute of Bioengineering, School of Engineering, EPFL, 1015 Lausanne, Switzerland
| | - M Graf
- †Laboratory of Nanoscale Biology, Institute of Bioengineering, School of Engineering, EPFL, 1015 Lausanne, Switzerland
| | - M Lihter
- †Laboratory of Nanoscale Biology, Institute of Bioengineering, School of Engineering, EPFL, 1015 Lausanne, Switzerland
- ‡Institut za fiziku, Bijenička 46, Zagreb, Croatia
| | - R D Bulushev
- †Laboratory of Nanoscale Biology, Institute of Bioengineering, School of Engineering, EPFL, 1015 Lausanne, Switzerland
| | - D Dumcenco
- §Laboratory of Nanoscale Electronics and Structure, Institute of Electrical Engineering, School of Engineering, EPFL, 1015 Lausanne, Switzerland
| | - D T L Alexander
- ∥Centre Interdisciplinaire de Microscopie Électronique (CIME), EPFL, 1015 Lausanne, Switzerland
| | - D Krasnozhon
- §Laboratory of Nanoscale Electronics and Structure, Institute of Electrical Engineering, School of Engineering, EPFL, 1015 Lausanne, Switzerland
| | - T Vuletic
- ‡Institut za fiziku, Bijenička 46, Zagreb, Croatia
| | - A Kis
- §Laboratory of Nanoscale Electronics and Structure, Institute of Electrical Engineering, School of Engineering, EPFL, 1015 Lausanne, Switzerland
| | - A Radenovic
- †Laboratory of Nanoscale Biology, Institute of Bioengineering, School of Engineering, EPFL, 1015 Lausanne, Switzerland
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2132
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Yuan X, Tang L, Liu S, Wang P, Chen Z, Zhang C, Liu Y, Wang W, Zou Y, Liu C, Guo N, Zou J, Zhou P, Hu W, Xiu F. Arrayed van der Waals Vertical Heterostructures Based on 2D GaSe Grown by Molecular Beam Epitaxy. Nano Lett 2015; 15:3571-7. [PMID: 25923041 DOI: 10.1021/acs.nanolett.5b01058] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Vertically stacking two-dimensional (2D) materials can enable the design of novel electronic and optoelectronic devices and realize complex functionality. However, the fabrication of such artificial heterostructures on a wafer scale with an atomically sharp interface poses an unprecedented challenge. Here, we demonstrate a convenient and controllable approach for the production of wafer-scale 2D GaSe thin films by molecular beam epitaxy. In situ reflection high-energy electron diffraction oscillations and Raman spectroscopy reveal a layer-by-layer van der Waals epitaxial growth mode. Highly efficient photodetector arrays were fabricated, based on few-layer GaSe on Si. These photodiodes show steady rectifying characteristics and a high external quantum efficiency of 23.6%. The resultant photoresponse is super-fast and robust, with a response time of 60 μs. Importantly, the device shows no sign of degradation after 1 million cycles of operation. We also carried out numerical simulations to understand the underlying device working principles. Our study establishes a new approach to produce controllable, robust, and large-area 2D heterostructures and presents a crucial step for further practical applications.
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Affiliation(s)
- Xiang Yuan
- †State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- ‡Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433, China
| | - Lei Tang
- †State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- ‡Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433, China
| | - Shanshan Liu
- †State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- ‡Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433, China
| | - Peng Wang
- §National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
| | - Zhigang Chen
- ∥Materials Engineering, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Cheng Zhang
- †State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- ‡Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433, China
| | - Yanwen Liu
- †State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- ‡Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433, China
| | - Weiyi Wang
- †State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- ‡Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433, China
| | - Yichao Zou
- ∥Materials Engineering, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Cong Liu
- §National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
| | - Nan Guo
- §National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
| | - Jin Zou
- ∥Materials Engineering, The University of Queensland, Brisbane, QLD 4072, Australia
- ⊥Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Peng Zhou
- #State Key Laboratory of ASIC and System, Department of Microelectronics, Fudan University, Shanghai 200433, China
| | - Weida Hu
- §National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
| | - Faxian Xiu
- †State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- ‡Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433, China
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2133
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Hill HM, Rigosi AF, Roquelet C, Chernikov A, Berkelbach TC, Reichman DR, Hybertsen MS, Brus LE, Heinz TF. Observation of Excitonic Rydberg States in Monolayer MoS2 and WS2 by Photoluminescence Excitation Spectroscopy. Nano Lett 2015; 15:2992-7. [PMID: 25816155 DOI: 10.1021/nl504868p] [Citation(s) in RCA: 124] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
We have identified excited exciton states in monolayers of MoS2 and WS2 supported on fused silica by means of photoluminescence excitation spectroscopy. In monolayer WS2, the positions of the excited A exciton states imply an exciton binding energy of 0.32 eV. In monolayer MoS2, excited exciton transitions are observed at energies of 2.24 and 2.34 eV. Assigning these states to the B exciton Rydberg series yields an exciton binding energy of 0.44 eV.
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Affiliation(s)
| | | | | | | | | | | | - Mark S Hybertsen
- §Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, United States
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2134
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Varghese JO, Agbo P, Sutherland AM, Brar VW, Rossman GR, Gray HB, Heath JR. The influence of water on the optical properties of single-layer molybdenum disulfide. Adv Mater 2015; 27:2734-2740. [PMID: 25787228 DOI: 10.1002/adma.201500555] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 02/26/2015] [Indexed: 06/04/2023]
Abstract
Adsorbed molecules can significantly affect the properties of atomically thin materials. Physisorbed water plays a significant role in altering the optoelectronic properties of single-layer MoS2 , one such 2D film. Here the distinct quenching effect of adsorbed water on the photoluminescence of single-layer MoS2 is demonstrated through scanning-probe and optical microscopy.
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Affiliation(s)
- Joseph O Varghese
- Division of Chemistry and Chemical Engineering, California Institute of Technology, MC 127-72, Pasadena, CA, 91125, USA
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2135
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Miao J, Hu W, Jing Y, Luo W, Liao L, Pan A, Wu S, Cheng J, Chen X, Lu W. Surface Plasmon-Enhanced Photodetection in Few Layer MoS2 Phototransistors with Au Nanostructure Arrays. Small 2015; 11:2392-8. [PMID: 25630636 DOI: 10.1002/smll.201403422] [Citation(s) in RCA: 124] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 12/23/2014] [Indexed: 05/11/2023]
Abstract
2D Molybdenum disulfide (MoS2 ) is a promising candidate material for high-speed and flexible optoelectronic devices, but only with low photoresponsivity. Here, a large enhancement of photocurrent response is obtained by coupling few-layer MoS2 with Au plasmonic nanostructure arrays. Au nanoparticles or nanoplates placed onto few-layer MoS2 surface can enhance the local optical field in the MoS2 layer, due to the localized surface plasmon (LSP) resonance. After depositing 4 nm thick Au nanoparticles sparsely onto few-layer MoS2 phototransistors, a doubled increase in the photocurrent response is observed. The photocurrent of few-layer MoS2 phototransistors exhibits a threefold enhancement with periodic Au nanoarrays. The simulated optical field distribution confirms that light can be trapped and enhanced near the Au nanoplates. These findings offer an avenue for practical applications of high performance MoS2 -based optoelectronic devices or systems in the future.
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Affiliation(s)
- Jinshui Miao
- National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yutian Road, Shanghai, 200083, P.R. China
| | - Weida Hu
- National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yutian Road, Shanghai, 200083, P.R. China
| | - Youliang Jing
- National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yutian Road, Shanghai, 200083, P.R. China
| | - Wenjin Luo
- National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yutian Road, Shanghai, 200083, P.R. China
| | - Lei Liao
- Department of Physics and Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education, Wuhan University, Wuhan, 430072, P.R. China
| | - Anlian Pan
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics (CBSC), Hunan University, Changsha, 410082, P.R. China
| | - Shiwei Wu
- State Key Laboratory of Surface Physics, Fudan University, Shanghai, 200438, P.R. China
| | - Jingxin Cheng
- State Key Laboratory of Surface Physics, Fudan University, Shanghai, 200438, P.R. China
| | - Xiaoshuang Chen
- National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yutian Road, Shanghai, 200083, P.R. China
| | - Wei Lu
- National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yutian Road, Shanghai, 200083, P.R. China
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2136
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Rong Y, He K, Pacios M, Robertson AW, Bhaskaran H, Warner JH. Controlled preferential oxidation of grain boundaries in monolayer tungsten disulfide for direct optical imaging. ACS Nano 2015; 9:3695-3703. [PMID: 25870912 DOI: 10.1021/acsnano.5b00852] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Synthetic 2D crystal films grown by chemical vapor deposition are typically polycrystalline, and determining grain size within domains and continuous films is crucial for determining their structure. Here we show that grain boundaries in the 2D transition metal dichalcogenide WS2, grown by CVD, can be preferentially oxidized by controlled heating in air. Under our developed conditions, preferential degradation at the grain boundaries causes an increase in their physical size due to oxidation. This increase in size enables their clear and rapid identification using a standard optical microscope. We demonstrate that similar treatments in an Ar environment do no show this effect, confirming that oxidation is the main role in the structural change. Statistical analysis of grain boundary (GB) angles shows dominant mirror formation. Electrical biasing across the GB is shown to lead to changes at the GB and their observation under an optical microscope. Our approach enables high-throughput screening of as-synthesized WS2 domains and continuous films to determine their crystallinity and should enable improvements in future CVD growth of these materials.
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Affiliation(s)
- Youmin Rong
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Kuang He
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Mercè Pacios
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Alex W Robertson
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Harish Bhaskaran
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Jamie H Warner
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, United Kingdom
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2137
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Rao CNR, Gopalakrishnan K, Maitra U. Comparative Study of Potential Applications of Graphene, MoS2, and Other Two-Dimensional Materials in Energy Devices, Sensors, and Related Areas. ACS Appl Mater Interfaces 2015; 7:7809-32. [PMID: 25822145 DOI: 10.1021/am509096x] [Citation(s) in RCA: 116] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Novel properties of graphene have been well documented, whereas the importance of nanosheets of MoS2 and other chalcogenides is increasingly being recognized over the last two to three years. Borocarbonitrides, BxCyNz, with insulating BN and conducting graphene on either side are new materials whose properties have been attracting attention. These two-dimensional (2D) materials contain certain common features. Thus, graphene, MoS2, and borocarbonitrides have all been used in supercapacitor applications, oxygen reduction reactions (ORRs), and lithium-ion batteries. It is instructive, therefore, to make a comparative study of some of the important properties of these layered materials. In this article, we discuss properties related to energy devices at length. We examine the hydrogen evolution reaction facilitated by graphene, MoS2, and related materials. We also discuss gas and radiation sensors based on graphene and MoS2 as well as gas storage properties of graphene and borocarbonitrides. The article should be useful in making a judicious choice of which 2D material to use for a particular application.
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Affiliation(s)
- C N R Rao
- Chemistry and Physics of Materials Unit, New Chemistry Unit, International Centre for Materials Science, CSIR Centre of Excellence in Chemistry and Sheik Saqr Laboratory, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India
| | - K Gopalakrishnan
- Chemistry and Physics of Materials Unit, New Chemistry Unit, International Centre for Materials Science, CSIR Centre of Excellence in Chemistry and Sheik Saqr Laboratory, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India
| | - Urmimala Maitra
- Chemistry and Physics of Materials Unit, New Chemistry Unit, International Centre for Materials Science, CSIR Centre of Excellence in Chemistry and Sheik Saqr Laboratory, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India
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2138
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Lu J, Lu JH, Liu H, Liu B, Gong L, Tok ES, Loh KP, Sow CH. Microlandscaping of Au nanoparticles on few-layer MoS2 films for chemical sensing. Small 2015; 11:1792-800. [PMID: 25581016 DOI: 10.1002/smll.201402591] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Revised: 11/18/2014] [Indexed: 05/13/2023]
Abstract
Surface modification or decoration of ultrathin MoS2 films with chemical moieties is appealing since nanointerfacing can functionalize MoS2 films with bonus potentials. In this work, a facile and effective method for microlandscaping of Au nanoparticles (NPs) on few-layer MoS2 films is developed. This approach first employs a focused laser beam to premodify the MoS2 films to achieve active surface domains with unbound sulfur. When the activated surface is subsequently immersed in AuCl3 solution, Au NPs are found to preferentially decorate onto the modified regions. As a result, Au NPs can be selectively and locally anchored onto designated regions on the MoS2 surface. With a scanning laser beam, microlandscapes comprising of Au NPs decorated on laser-defined micropatterns are constructed. By varying the laser power, reaction time and thickness of the MoS2 films, the size and density of the NPs can be controlled. The resulting hybrid materials are demonstrated as efficient Raman active surfaces for the detection of aromatic molecules with high sensitivity.
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Affiliation(s)
- Junpeng Lu
- Department of Physics, 2 Science Drive 3, National University of Singapore, 117542, Singapore
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2139
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Abstract
The mechanical properties of 2D materials such as monolayer graphene are of extreme importance for several potential applications. We summarize the experimental and theoretical results to date on mechanical loading of freely suspended or fully supported graphene. We assess the obtained axial properties of the material in tension and compression and comment on the methods used for deriving the various reported values. We also report on past and current efforts to define the elastic constants of graphene in a 3D representation. Current areas of research that are concerned with the effect of production method and/or the presence of defects upon the mechanical integrity of graphene are also covered. Finally, we examine extensively the work related to the effect of graphene deformation upon its electronic properties and the possibility of employing strained graphene in future electronic applications.
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Affiliation(s)
- Costas Galiotis
- Institute of Chemical Engineering Sciences, Foundation of Research and Technology-Hellas (FORTH/ICE-HT), 26504 Patras, Greece; , ,
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2140
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Keuleyan S, Wang M, Chung FR, Commons J, Koski KJ. A silicon-based two-dimensional chalcogenide: growth of Si₂Te₃ nanoribbons and nanoplates. Nano Lett 2015; 15:2285-2290. [PMID: 25764295 DOI: 10.1021/nl504330g] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report the synthesis of high-quality single-crystal two-dimensional, layered nanostructures of silicon telluride, Si2Te3, in multiple morphologies controlled by substrate temperature and Te seeding. Morphologies include nanoribbons formed by VLS growth from Te droplets, vertical hexagonal nanoplates through vapor-solid crystallographically oriented growth on amorphous oxide substrates, and flat hexagonal nanoplates formed through large-area VLS growth in liquid Te pools. We show the potential for doping through the choice of substrate and growth conditions. Vertical nanoplates grown on sapphire substrates, for example, can incorporate a uniform density of Al atoms from the substrate. We also show that the material may be modified after synthesis, including both mechanical exfoliation (reducing the thickness to as few as five layers) and intercalation of metal ions including Li(+) and Mg(2+), which suggests applications in energy storage materials. The material exhibits an intense red color corresponding to its strong and broad interband absorption extending from the red into the infrared. Si2Te3 enjoys chemical and processing compatibility with other silicon-based material including amorphous SiO2 but is very chemically sensitive to its environment, which suggests applications in silicon-based devices ranging from fully integrated thermoelectrics to optoelectronics to chemical sensors.
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Affiliation(s)
- Sean Keuleyan
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Mengjing Wang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Frank R Chung
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Jeffrey Commons
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Kristie J Koski
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
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2141
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Abstract
Single-layer direct band gap semiconductors such as transition metal dichalcogenides are quite attractive for a wide range of electronics, photonics, and optoelectronics applications. Their monolayer thickness provides significant advantages in many applications such as field-effect transistors for high-performance electronics, sensor/detector applications, and flexible electronics. However, for optoelectronics and photonics applications, inherent monolayer thickness poses a significant challenge for the interaction of light with the material, which therefore results in poor light emission and absorption behavior. Here, we demonstrate enhanced light emission from large-area monolayer MoS2 using plasmonic silver nanodisc arrays, where enhanced photoluminescence up to 12-times has been measured. Observed phenomena stem from the fact that plasmonic resonance couples to both excitation and emission fields and thus boosts the light-matter interaction at the nanoscale. Reported results allow us to engineer light-matter interactions in two-dimensional materials and could enable highly efficient photodetectors, sensors, and photovoltaic devices, where photon absorption and emission efficiency highly dictate the device performance.
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Affiliation(s)
- Serkan Butun
- †Department of Electrical Engineering and Computer Science, Northwestern University, Evanston, Illinois 60208, United States
| | - Sefaattin Tongay
- ‡School for Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, Arizona 85287, United States
| | - Koray Aydin
- †Department of Electrical Engineering and Computer Science, Northwestern University, Evanston, Illinois 60208, United States
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2142
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Abstract
Molybdenum trioxide (α-MoO3) is a 2D layered oxide with use in electrochromic and photochromic devices owing to its ability to reversibly change color between transparent and light blue with electrochemical or hydrogen intercalation. Despite its significant application potential, MoO3 performance is largely limited by the destructiveness of these intercalation techniques, insignificant coloration, and slow color response. We demonstrate a reversible chemochromic method, using intercalation of zerovalent metals into α-MoO3 nanoribbons (Sn, ∼2 at. %; Co, ∼4 at. %), to chemically alter MoO3 from transparent white to a deep blue indigo, resulting in enhanced coloration and chemically tunable optical properties. We present two strategies to reversibly tune the color response of MoO3 nanoribbons. Chromism can be reversed (i) by complete oxidative deintercalation with hydrogen peroxide or iodine or (ii) through a temperature-driven disorder-order phase transition of the intercalated zerovalent metal.
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Affiliation(s)
- Mengjing Wang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Kristie J Koski
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
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2143
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Yasaei P, Kumar B, Foroozan T, Wang C, Asadi M, Tuschel D, Indacochea JE, Klie RF, Salehi-Khojin A. High-quality black phosphorus atomic layers by liquid-phase exfoliation. Adv Mater 2015; 27:1887-92. [PMID: 25645510 DOI: 10.1002/adma.201405150] [Citation(s) in RCA: 353] [Impact Index Per Article: 39.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 12/26/2014] [Indexed: 05/21/2023]
Affiliation(s)
- Poya Yasaei
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, 60607, USA
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2144
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Yang S, Wang C, Sahin H, Chen H, Li Y, Li SS, Suslu A, Peeters FM, Liu Q, Li J, Tongay S. Tuning the optical, magnetic, and electrical properties of ReSe2 by nanoscale strain engineering. Nano Lett 2015; 15:1660-6. [PMID: 25642738 DOI: 10.1021/nl504276u] [Citation(s) in RCA: 160] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Creating materials with ultimate control over their physical properties is vital for a wide range of applications. From a traditional materials design perspective, this task often requires precise control over the atomic composition and structure. However, owing to their mechanical properties, low-dimensional layered materials can actually withstand a significant amount of strain and thus sustain elastic deformations before fracture. This, in return, presents a unique technique for tuning their physical properties by "strain engineering". Here, we find that local strain induced on ReSe2, a new member of the transition metal dichalcogenides family, greatly changes its magnetic, optical, and electrical properties. Local strain induced by generation of wrinkle (1) modulates the optical gap as evidenced by red-shifted photoluminescence peak, (2) enhances light emission, (3) induces magnetism, and (4) modulates the electrical properties. The results not only allow us to create materials with vastly different properties at the nanoscale, but also enable a wide range of applications based on 2D materials, including strain sensors, stretchable electrodes, flexible field-effect transistors, artificial-muscle actuators, solar cells, and other spintronic, electromechanical, piezoelectric, photonic devices.
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Affiliation(s)
- Shengxue Yang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences , P.O. Box 912, Beijing 100083, China
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2145
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Song EH, Kang BH, Kim TY, Lee HJ, Park YW, Kim YC, Ju BK. Highly oriented gold/nanoclay-polymer nanocomposites for flexible gas barrier films. ACS Appl Mater Interfaces 2015; 7:4778-4783. [PMID: 25668131 DOI: 10.1021/am508641g] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Layer-by-layer (LBL) assembly, which uses electronic and ionic intermolecular bonding under nonvacuum conditions, is a promising technology for fabricating gas barrier films owing to its simple processing and easy formation of a multilayer structure. In this research, nanoclay-polymer multilayers of Na(+)-montmorillonite (Na-MMT) were fabricated. Particularly, the addition of AuCl3 on fabricated MMT layers caused a reaction with the surface silanol functional groups (Si-O-H) of the MMT platelets, resulting in the formation of Au2O3 on the MMT-polymer multilayers. The Au2O3 filled the vacancies between the MMT platelets and linked the MMT platelets together, thus forming a gas barrier film that reduced the water vapor transmission rate (WVTR) to 3.2 × 10(-3) g m(-2) day(-1). AuCl3-treated MMT-polymer multilayers thus have the potential to be utilized for manufacturing gas barrier films for flexible electronics on a large scale.
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Affiliation(s)
- Eun-Ho Song
- Display and Nanosystem Laboratory, College of Engineering, and ‡The Institute of High Technology Materials and Devices, Korea University , Seoul 136-713, Republic of Korea
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2146
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Tarasov A, Zhang S, Tsai MY, Campbell PM, Graham S, Barlow S, Marder SR, Vogel EM. Controlled doping of large-area trilayer MoS2 with molecular reductants and oxidants. Adv Mater 2015; 27:1175-81. [PMID: 25580926 DOI: 10.1002/adma.201404578] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Revised: 11/19/2014] [Indexed: 05/13/2023]
Abstract
Highly uniform large-area MoS2 is chemically doped using molecular reductants and oxidants. Electrical measurements, photoemission, and Raman spectroscopy are used to study the doping effect and to understand the underlying mechanism. Strong work-function changes of up to ±1 eV can be achieved, with contributions from state filling and surface dipoles. This results in high doping densities of up to ca. 8 × 10(12) cm(-2) .
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Affiliation(s)
- Alexey Tarasov
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
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2147
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Lien DH, Kang JS, Amani M, Chen K, Tosun M, Wang HP, Roy T, Eggleston MS, Wu MC, Dubey M, Lee SC, He JH, Javey A. Engineering light outcoupling in 2D materials. Nano Lett 2015; 15:1356-61. [PMID: 25602462 DOI: 10.1021/nl504632u] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
When light is incident on 2D transition metal dichalcogenides (TMDCs), it engages in multiple reflections within underlying substrates, producing interferences that lead to enhancement or attenuation of the incoming and outgoing strength of light. Here, we report a simple method to engineer the light outcoupling in semiconducting TMDCs by modulating their dielectric surroundings. We show that by modulating the thicknesses of underlying substrates and capping layers, the interference caused by substrate can significantly enhance the light absorption and emission of WSe2, resulting in a ∼11 times increase in Raman signal and a ∼30 times increase in the photoluminescence (PL) intensity of WSe2. On the basis of the interference model, we also propose a strategy to control the photonic and optoelectronic properties of thin-layer WSe2. This work demonstrates the utilization of outcoupling engineering in 2D materials and offers a new route toward the realization of novel optoelectronic devices, such as 2D LEDs and solar cells.
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Affiliation(s)
- Der-Hsien Lien
- Electrical Engineering and Computer Sciences, University of California , Berkeley, California 94720, United States
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2148
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Kim DW, Ok JM, Jung WB, Kim JS, Kim SJ, Choi HO, Kim YH, Jung HT. Direct observation of molybdenum disulfide, MoS2, domains by using a liquid crystalline texture method. Nano Lett 2015; 15:229-234. [PMID: 25494827 DOI: 10.1021/nl5034528] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Because the properties of molybdenum disulfide (MoS2) are strongly influenced by the sizes and boundaries of its domains, the direct visualization of large-area MoS2 domains is one of the most important challenges in MoS2 research. In the current study, we developed a simple and rapid method to observe and determine the boundaries of MoS2 domains. The technique, which depends on observations of nematic liquid crystal textures on the MoS2 surface, does not damage the sample and is not limited by domain size. Thus, this approach should significantly aid not only efforts aimed at gaining an understanding of the relationships between grain boundaries and properties of MoS2 but also those focusing on how domain sizes are controlled during large-area synthesis.
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Affiliation(s)
- Dae Woo Kim
- National Research Lab for Organic Optoelectronic Materials, Department of Chemical and Biomolecular Engineering (BK-21 plus), Korea Advanced Institute of Science and Technology , Daejeon 305-701, Korea
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2149
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Ceballos F, Bellus MZ, Chiu HY, Zhao H. Ultrafast charge separation and indirect exciton formation in a MoS2-MoSe2 van der Waals heterostructure. ACS Nano 2014; 8:12717-24. [PMID: 25402669 DOI: 10.1021/nn505736z] [Citation(s) in RCA: 285] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
We observe subpicosecond charge separation and formation of indirect excitons a van der Waals heterostructure formed by molybdenum disulfide and molybdenum diselenide monolayers. The sample is fabricated by manually stacking monolayer MoS2 and MoSe2 flakes prepared by mechanical exfoliation. Photoluminescence measurements confirm the formation of an effective heterojunction. In the transient absorption measurements, an ultrafast laser pulse resonantly injects excitons in the MoSe2 layer of the heterostructure. Differential reflection of a probe pulse tuned to the MoS2 exciton resonance is immediately observed following the pump excitation. This proves ultrafast transfer of electrons from MoSe2 to MoS2 layers, despite the strong Coulomb attraction from the holes in the resonantly excited excitons. Conversely, when excitons are selectively injected in MoS2, holes transfer to MoSe2 on an ultrafast time scale, too, as observed by measuring the differential reflection of a probe tuned to the MoSe2 resonance. The ultrafast charge transfer process is followed by the formation of spatially indirect excitons with electrons and holes residing in different layers. The lifetime of these indirect excitons are found to be longer than that of the direct excitons in individual MoS2 and MoSe2 monolayers.
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Affiliation(s)
- Frank Ceballos
- Department of Physics and Astronomy, The University of Kansas , Lawrence, Kansas 66045, United States
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2150
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Tan Y, Liu P, Chen L, Cong W, Ito Y, Han J, Guo X, Tang Z, Fujita T, Hirata A, Chen MW. Monolayer MoS2 films supported by 3D nanoporous metals for high-efficiency electrocatalytic hydrogen production. Adv Mater 2014; 26:8023-8. [PMID: 25363090 DOI: 10.1002/adma.201403808] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Revised: 09/26/2014] [Indexed: 05/08/2023]
Abstract
The "edge-free" monolayer MoS2 films supported by 3D nanoporous gold show high catalytic activities towards hydrogen evolution reaction (HER), originating from large out-of-plane strains that are geometrically required to manage the 3D curvature of bicontinuous nanoporosity. The large lattice bending leads to local semiconductor-to-metal transition of 2H MoS2 and the formation of catalytically active sites for HER.
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Affiliation(s)
- Yongwen Tan
- WPI Advanced Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan
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