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Zheng Z, Zeng T, Zhao T, Shi S, Ren L, Zhang T, Jia L, Gu Y, Xiao R, Zhou H, Zhang Q, Lu J, Wang G, Zhao C, Li H, Tay BK, Chen J. Effective electrical manipulation of a topological antiferromagnet by orbital torques. Nat Commun 2024; 15:745. [PMID: 38272914 PMCID: PMC10811228 DOI: 10.1038/s41467-024-45109-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Accepted: 01/09/2024] [Indexed: 01/27/2024] Open
Abstract
The electrical control of the non-trivial topology in Weyl antiferromagnets is of great interest for the development of next-generation spintronic devices. Recent studies suggest that the spin Hall effect can switch the topological antiferromagnetic order. However, the switching efficiency remains relatively low. Here, we demonstrate the effective manipulation of antiferromagnetic order in the Weyl semimetal Mn3Sn using orbital torques originating from either metal Mn or oxide CuOx. Although Mn3Sn can convert orbital current to spin current on its own, we find that inserting a heavy metal layer, such as Pt, of appropriate thickness can effectively reduce the critical switching current density by one order of magnitude. In addition, we show that the memristor-like switching behaviour of Mn3Sn can mimic the potentiation and depression processes of a synapse with high linearity-which may be beneficial for constructing accurate artificial neural networks. Our work paves a way for manipulating the topological antiferromagnetic order and may inspire more high-performance antiferromagnetic functional devices.
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Affiliation(s)
- Zhenyi Zheng
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Tao Zeng
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Tieyang Zhao
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Shu Shi
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Lizhu Ren
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Tongtong Zhang
- Centre for Micro- and Nano-Electronics (CMNE), School of Electrical and Electronic Engineering, Nanyang Technological University, 639798, Singapore, Singapore
| | - Lanxin Jia
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Youdi Gu
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Rui Xiao
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Hengan Zhou
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Qihan Zhang
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Jiaqi Lu
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Guilei Wang
- Beijing Superstring Academy of Memory Technology, Beijing, 100176, China
| | - Chao Zhao
- Beijing Superstring Academy of Memory Technology, Beijing, 100176, China
| | - Huihui Li
- Beijing Superstring Academy of Memory Technology, Beijing, 100176, China.
| | - Beng Kang Tay
- Centre for Micro- and Nano-Electronics (CMNE), School of Electrical and Electronic Engineering, Nanyang Technological University, 639798, Singapore, Singapore.
| | - Jingsheng Chen
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore.
- Chongqing Research Institute, National University of Singapore, Chongqing, 401120, China.
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2
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Hu Y, Rogée L, Wang W, Zhuang L, Shi F, Dong H, Cai S, Tay BK, Lau SP. Extendable piezo/ferroelectricity in nonstoichiometric 2D transition metal dichalcogenides. Nat Commun 2023; 14:8470. [PMID: 38123543 PMCID: PMC10733392 DOI: 10.1038/s41467-023-44298-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 12/07/2023] [Indexed: 12/23/2023] Open
Abstract
Engineering piezo/ferroelectricity in two-dimensional materials holds significant implications for advancing the manufacture of state-of-the-art multifunctional materials. The inborn nonstoichiometric propensity of two-dimensional transition metal dichalcogenides provides a spiffy ready-available solution for breaking inversion centrosymmetry, thereby conducing to circumvent size effect challenges in conventional perovskite oxide ferroelectrics. Here, we show the extendable and ubiquitous piezo/ferroelectricity within nonstoichiometric two-dimensional transition metal dichalcogenides that are predominantly centrosymmetric during standard stoichiometric cases. The emerged piezo/ferroelectric traits are aroused from the sliding of van der Waals layers and displacement of interlayer metal atoms triggered by the Frankel defects of heterogeneous interlayer native metal atom intercalation. We demonstrate two-dimensional chromium selenides nanogenerator and iron tellurides ferroelectric multilevel memristors as two representative applications. This innovative approach to engineering piezo/ferroelectricity in ultrathin transition metal dichalcogenides may provide a potential avenue to consolidate piezo/ferroelectricity with featured two-dimensional materials to fabricate multifunctional materials and distinguished multiferroic.
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Affiliation(s)
- Yi Hu
- Department of Applied Physics, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, PR China
- Centre for Micro- and Nano-Electronics (CMNE), School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 638798, Singapore
| | - Lukas Rogée
- Department of Applied Physics, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, PR China
| | - Weizhen Wang
- Department of Applied Physics, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, PR China
| | - Lyuchao Zhuang
- Department of Applied Physics, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, PR China
| | - Fangyi Shi
- Department of Applied Physics, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, PR China
| | - Hui Dong
- Department of Applied Physics, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, PR China
| | - Songhua Cai
- Department of Applied Physics, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, PR China
| | - Beng Kang Tay
- Centre for Micro- and Nano-Electronics (CMNE), School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 638798, Singapore
- IRL 3288 CINTRA (CNRS-NTU-THALES Research Alliances), Nanyang Technological University, Singapore, 637553, Singapore
| | - Shu Ping Lau
- Department of Applied Physics, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, PR China.
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Fu Q, Cong X, Xu X, Zhu S, Zhao X, Liu S, Yao B, Xu M, Deng Y, Zhu C, Wang X, Kang L, Zeng Q, Lin ML, Wang X, Tang B, Yang J, Dong Z, Liu F, Xiong Q, Zhou J, Wang Q, Li X, Tan PH, Tay BK, Liu Z. Berry Curvature Dipole Induced Giant Mid-Infrared Second-Harmonic Generation in 2D Weyl Semiconductor. Adv Mater 2023; 35:e2306330. [PMID: 37737448 DOI: 10.1002/adma.202306330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 09/05/2023] [Indexed: 09/23/2023]
Abstract
Due to its inversion-broken triple helix structure and the nature of Weyl semiconductor, 2D Tellurene (2D Te) is promising to possess a strong nonlinear optical response in the infrared region, which is rarely reported in 2D materials. Here, a giant nonlinear infrared response induced by large Berry curvature dipole (BCD) is demonstrated in the Weyl semiconductor 2D Te. Ultrahigh second-harmonic generation response is acquired from 2D Te with a large second-order nonlinear optical susceptibility (χ(2) ), which is up to 23.3 times higher than that of monolayer MoS2 in the range of 700-1500 nm. Notably, distinct from other 2D nonlinear semiconductors, χ(2) of 2D Te increases extraordinarily with increasing wavelength and reaches up to 5.58 nm V-1 at ≈2300 nm, which is the best infrared performance among the reported 2D nonlinear materials. Large χ(2) of 2D Te also enables the high-intensity sum-frequency generation with an ultralow continuous-wave (CW) pump power. Theoretical calculations reveal that the exceptional performance is attributed to the presence of large BCD located at the Weyl points of 2D Te. These results unravel a new linkage between Weyl semiconductor and strong optical nonlinear responses, rendering 2D Te a competitive candidate for highly efficient nonlinear 2D semiconductors in the infrared region.
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Affiliation(s)
- Qundong Fu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
- IRL 3288 CINTRA (CNRS-NTU-THALES Research Alliances), Nanyang Technological University, Singapore, 637553, Singapore
| | - Xin Cong
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, P. R. China
| | - Xiaodong Xu
- School of Materials Science and Engineering, Harbin Institute of Technology, Harbin, 150001, P. R. China
| | - Song Zhu
- School of Electrical & Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Xiaoxu Zhao
- School of Materials Science and Engineering, Peking University, Beijing, 100871, P. R. China
| | - Sheng Liu
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Bingqing Yao
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Manzhang Xu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Ya Deng
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Chao Zhu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Xiaowei Wang
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Lixing Kang
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Qingsheng Zeng
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Miao-Ling Lin
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, P. R. China
| | - Xingli Wang
- IRL 3288 CINTRA (CNRS-NTU-THALES Research Alliances), Nanyang Technological University, Singapore, 637553, Singapore
| | - Bijun Tang
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Jianqun Yang
- School of Materials Science and Engineering, Harbin Institute of Technology, Harbin, 150001, P. R. China
| | - Zhili Dong
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Fucai Liu
- School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, 610054, P. R. China
| | - Qihua Xiong
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, 100084, P. R. China
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, P. R. China
| | - Jiadong Zhou
- Key Lab of advanced optoelectronic quantum architecture and measurement (Ministry of Education), Beijing Key Lab of Nanophotonics & Ultrafine Optoelectronic Systems, and School of Physics, Beijing Institute of Technology, Beijing, 100081, P. R. China
| | - Qijie Wang
- IRL 3288 CINTRA (CNRS-NTU-THALES Research Alliances), Nanyang Technological University, Singapore, 637553, Singapore
- School of Electrical & Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Xingji Li
- School of Materials Science and Engineering, Harbin Institute of Technology, Harbin, 150001, P. R. China
| | - Ping-Heng Tan
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, P. R. China
| | - Beng Kang Tay
- IRL 3288 CINTRA (CNRS-NTU-THALES Research Alliances), Nanyang Technological University, Singapore, 637553, Singapore
| | - Zheng Liu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
- IRL 3288 CINTRA (CNRS-NTU-THALES Research Alliances), Nanyang Technological University, Singapore, 637553, Singapore
- Institute for Functional Intelligent Materials, National University of Singapore, Blk S9, Level 9, 4 Science Drive 2, Singapore, 117544, Singapore
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Wang X, Ge J, Ang NRX, Liang K, Tan CW, Li H, Tay BK. Low-Power Magnetron Sputtering Deposition of Antimonene Nanofilms for Water Splitting Reaction. Micromachines (Basel) 2022; 13:mi13030489. [PMID: 35334781 PMCID: PMC8951292 DOI: 10.3390/mi13030489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 03/16/2022] [Accepted: 03/17/2022] [Indexed: 11/16/2022]
Abstract
Antimonene (Sb) is a novel kind of two-dimensional (2D) material that is predicted to be promising for various applications, such as water splitting and semiconductor devices. Several methods have been reported to prepare Sb nanoflakes/nanofilms; however, it is still relatively difficult to prepare Sb nanofilms. In this work, a method of low-power magnetron sputtering deposition was used for the preparation of Sb nanofilms with lateral dimensions on the centimeter scale and controllable film thickness. It was found that the control of the deposition temperature is important for the final crystalline structure of the nanofilms. Furthermore, the application of the nanofilms as a catalyst for water splitting (hydrogen evolution reaction (HER) and oxygen evolution reaction (OER)) was demonstrated.
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Affiliation(s)
- Xingli Wang
- UMI 3288 CINTRA (CNRS International-NTU-THALES Research Alliances), Nanyang Technological University, Singapore 637553, Singapore; (X.W.); (J.G.); (K.L.); (C.-W.T.); (H.L.)
- Centre for Micro- and Nano-Electronics (CMNE), School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 638798, Singapore;
| | - Junyu Ge
- UMI 3288 CINTRA (CNRS International-NTU-THALES Research Alliances), Nanyang Technological University, Singapore 637553, Singapore; (X.W.); (J.G.); (K.L.); (C.-W.T.); (H.L.)
- School of Mechanical and Aerospace, Nanyang Technological University, Singapore 639798, Singapore
| | - Nicole Ru-Xuan Ang
- Centre for Micro- and Nano-Electronics (CMNE), School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 638798, Singapore;
| | - Kun Liang
- UMI 3288 CINTRA (CNRS International-NTU-THALES Research Alliances), Nanyang Technological University, Singapore 637553, Singapore; (X.W.); (J.G.); (K.L.); (C.-W.T.); (H.L.)
- Centre for Micro- and Nano-Electronics (CMNE), School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 638798, Singapore;
| | - Chong-Wei Tan
- UMI 3288 CINTRA (CNRS International-NTU-THALES Research Alliances), Nanyang Technological University, Singapore 637553, Singapore; (X.W.); (J.G.); (K.L.); (C.-W.T.); (H.L.)
- Centre for Micro- and Nano-Electronics (CMNE), School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 638798, Singapore;
| | - Hong Li
- UMI 3288 CINTRA (CNRS International-NTU-THALES Research Alliances), Nanyang Technological University, Singapore 637553, Singapore; (X.W.); (J.G.); (K.L.); (C.-W.T.); (H.L.)
- Centre for Micro- and Nano-Electronics (CMNE), School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 638798, Singapore;
- School of Mechanical and Aerospace, Nanyang Technological University, Singapore 639798, Singapore
| | - Beng Kang Tay
- UMI 3288 CINTRA (CNRS International-NTU-THALES Research Alliances), Nanyang Technological University, Singapore 637553, Singapore; (X.W.); (J.G.); (K.L.); (C.-W.T.); (H.L.)
- Centre for Micro- and Nano-Electronics (CMNE), School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 638798, Singapore;
- Correspondence:
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Goh SCK, Wu W, Siah CF, Phee DKY, Liu A, Tay BK. Surface disinfection with silver loaded pencil graphite prepared with green UV photoreduction technique. Nanotechnology 2022; 33:235602. [PMID: 35158341 DOI: 10.1088/1361-6528/ac54dd] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 02/14/2022] [Indexed: 06/14/2023]
Abstract
Carbon-based materials have been studied for their antimicrobial properties. Previously, most antimicrobial studies are investigated with suspended nanoparticles in a liquid medium. Most works are often carried out with highly ordered pyrolytic graphite. These materials are expensive and are not viable for mass use on high-touch surfaces. Additionally, highly antimicrobial silver nanoparticles are often incorporated onto substrates by chemical reduction. At times, harmful chemicals are used. In this work, low-cost graphite pencils are mechanically exfoliated and transferred onto Si substrates. The sparsely-covered graphite flakes are treated by either plasma O2or UV irradiation. Subsequently, Ag is photo reduced in the presence of UV onto selected graphite flake samples. It is found that graphite flake surface topography and defects are dependent on the treatment process. High surface roughness and (defects density,ID/IG) are induced by plasma O2follows by UV and pristine graphite flake as follows: 6.45 nm (0.62), 4.96 nm (0.5), 3.79 nm (0.47). Antimicrobial tests withE. colireveal high killing efficiency by photoreduced Ag-on-graphite flake. The reversible effect of Ag leaching can be compensated by repeating the photoreduction process. This work proposes that UV treatment is a promising technique over that of plasma O2in view that the latter treated surface could repel bacteria resulting in lower bacteria-killing efficiency.
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Affiliation(s)
- Simon Chun Kiat Goh
- CINTRA, Nanyang Technological University, 639798, Singapore
- School of Electrical and Electronic, Nanyang Technological University, 639798, Singapore
| | - Wenshuai Wu
- School of Electrical and Electronic, Nanyang Technological University, 639798, Singapore
| | - Chun Fei Siah
- School of Electrical and Electronic, Nanyang Technological University, 639798, Singapore
| | - Derek Keng Yang Phee
- School of Electrical and Electronic, Nanyang Technological University, 639798, Singapore
| | - Aiqun Liu
- School of Electrical and Electronic, Nanyang Technological University, 639798, Singapore
| | - Beng Kang Tay
- CINTRA, Nanyang Technological University, 639798, Singapore
- School of Electrical and Electronic, Nanyang Technological University, 639798, Singapore
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Lum L, Tan CW, Siah CF, Liang K, Tay BK. Graphitisation of Waste Carbon Powder with Femtosecond Laser Annealing. Micromachines 2022; 13:mi13010120. [PMID: 35056285 PMCID: PMC8779221 DOI: 10.3390/mi13010120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Revised: 01/07/2022] [Accepted: 01/10/2022] [Indexed: 02/04/2023]
Abstract
Graphitisation of structural characteristics and improvement in electrical conductivity was reported onto waste carbon powder through femtosecond laser annealing. Raman spectroscopy on the carbon powder pre- and post-annealing showed a shift from amorphous-like carbon to graphitic-like carbon, which can be explained by the three-stage model. Electrical I-V probing of the samples revealed an increase in conductivity by up to 90%. An increase in incident laser power was found to be correlated to an increase in conductivity. An average incident laser power of 0.104 W or less showed little to no change in electrical characteristics, while an average incident laser power of greater than 1.626 W had a destructive effect on the carbon powder, shown through the reduction in powder. The most significant improvement in electrical conductivity has been observed at laser powers ranging from 0.526 to 1.286 W. To conclude, the graphitisation of waste carbon powder is possible using post-process femtosecond laser annealing to alter its electrical conductivity for future applications.
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Affiliation(s)
- Lucas Lum
- Centre for Micro- and Nano-Electronics (CMNE), School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Ave, Singapore 639798, Singapore; (L.L.); (C.-W.T.); (C.F.S.); (K.L.)
| | - Chong-Wei Tan
- Centre for Micro- and Nano-Electronics (CMNE), School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Ave, Singapore 639798, Singapore; (L.L.); (C.-W.T.); (C.F.S.); (K.L.)
| | - Chun Fei Siah
- Centre for Micro- and Nano-Electronics (CMNE), School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Ave, Singapore 639798, Singapore; (L.L.); (C.-W.T.); (C.F.S.); (K.L.)
| | - Kun Liang
- Centre for Micro- and Nano-Electronics (CMNE), School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Ave, Singapore 639798, Singapore; (L.L.); (C.-W.T.); (C.F.S.); (K.L.)
- CNRS-NTU-THALES Research Alliances/UMI 3288, Research Techno Plaza, 50 Nanyang Ave, Singapore 637553, Singapore
| | - Beng Kang Tay
- Centre for Micro- and Nano-Electronics (CMNE), School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Ave, Singapore 639798, Singapore; (L.L.); (C.-W.T.); (C.F.S.); (K.L.)
- CNRS-NTU-THALES Research Alliances/UMI 3288, Research Techno Plaza, 50 Nanyang Ave, Singapore 637553, Singapore
- Correspondence:
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Chi X, Guo R, Xiong J, Ren L, Peng X, Tay BK, Chen J. Enhanced Tunneling Magnetoresistance Effect via Ferroelectric Control of Interface Electronic/Magnetic Reconstructions. ACS Appl Mater Interfaces 2021; 13:56638-56644. [PMID: 34786928 DOI: 10.1021/acsami.1c15836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Magnetic tunnel junctions (MTJs) with tunable tunneling magnetoresistances (TMR) have already been proven to have great potential for spintronics. Especially, when ferroelectric materials are used as insulating barriers, more novel functions of MTJs can be realized due to interface magnetoelectric coupling. Here, we demonstrate a very large ferroelectric modulation of TMR (as high as 570% in low-resistance state) in the ferroelectric/magnetic La0.5Sr0.5MnO3/BaTiO3 (LSMO/BTO) junctions and find robust interfacial electronic and magnetic reconstructions via ferroelectric polarization switching. Through electrical, magnetic, and optical measurements combined with X-ray absorption and magnetic circular dichroism, we reveal that the interfacial electronic and magnetic (ferromagnetic/antiferromagnetic phase transition) reconstructions originate from strong electromagnetic coupling between BTO and LSMO at the interface and are driven by the modulation of hole/electron doping at the interface of LSMO/BTO through ferroelectric polarization switching. As a result, the ferroelectrically controlled interface barrier height and width and spin filter effect enable a giant electrical modulation of TMR. Our results shed new light on the intrinsic mechanisms governing magnetoelectric coupling and offering a new route to enhance magnetoelectric coupling for spin control in spintronic devices.
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Affiliation(s)
- Xiao Chi
- State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510641, China
| | - Rui Guo
- Department of Materials Science and Engineering, National University of Singapore, 117575, Singapore
- Centre for Micro- and Nano-Electronics (CMNE), School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore
- UMI 3288 CINTRA (CNRS-NTU-THALES Research Alliances), Nanyang Technological University, Research Techno Plaza, 50 Nanyang Drive, 637553 Singapore
| | - Juxia Xiong
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, P.R. China
| | - Lizhu Ren
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117583 Singapore
| | - Xinwen Peng
- State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510641, China
| | - Beng Kang Tay
- Centre for Micro- and Nano-Electronics (CMNE), School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore
- UMI 3288 CINTRA (CNRS-NTU-THALES Research Alliances), Nanyang Technological University, Research Techno Plaza, 50 Nanyang Drive, 637553 Singapore
| | - Jingsheng Chen
- Department of Materials Science and Engineering, National University of Singapore, 117575, Singapore
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Siah CF, Lum LYX, Wang J, Goh SCK, Tan CW, Hu L, Coquet P, Li H, Tan CS, Tay BK. Development of a CMOS-Compatible Carbon Nanotube Array Transfer Method. Micromachines (Basel) 2021; 12:mi12010095. [PMID: 33477456 PMCID: PMC7830489 DOI: 10.3390/mi12010095] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/13/2021] [Accepted: 01/16/2021] [Indexed: 11/16/2022]
Abstract
Carbon nanotubes (CNTs) have, over the years, been used in research as a promising material in electronics as a thermal interface material and as interconnects amongst other applications. However, there exist several issues preventing the widespread integration of CNTs onto device applications, e.g., high growth temperature and interfacial resistance. To overcome these issues, a complementary metal oxide semiconductor (CMOS)-compatible CNT array transfer method that electrically connects the CNT arrays to target device substrates was developed. The method separates the CNT growth and preparation steps from the target substrate. Utilizing an alignment tool with the capabilities of thermocompression enables a highly accurate transfer of CNT arrays onto designated areas with desired patterns. With this transfer process as a starting point, improvement pointers are also discussed in this paper to further improve the quality of the transferred CNTs.
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Affiliation(s)
- Chun Fei Siah
- Centre for Micro- and Nano-Electronics (CMNE), School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Ave, Singapore 639798, Singapore; (C.F.S.); (L.Y.X.L.); (C.W.T.); (L.H.); (C.S.T.)
| | - Lucas Yu Xiang Lum
- Centre for Micro- and Nano-Electronics (CMNE), School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Ave, Singapore 639798, Singapore; (C.F.S.); (L.Y.X.L.); (C.W.T.); (L.H.); (C.S.T.)
| | - Jianxiong Wang
- CNRS-NTU-THALES Research Alliances/UMI 3288, Research Techno Plaza, 50 Nanyang Ave, Border X Block, Level 6, Singapore 637553, Singapore; (J.W.); (S.C.K.G.); (P.C.); (H.L.)
| | - Simon Chun Kiat Goh
- CNRS-NTU-THALES Research Alliances/UMI 3288, Research Techno Plaza, 50 Nanyang Ave, Border X Block, Level 6, Singapore 637553, Singapore; (J.W.); (S.C.K.G.); (P.C.); (H.L.)
| | - Chong Wei Tan
- Centre for Micro- and Nano-Electronics (CMNE), School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Ave, Singapore 639798, Singapore; (C.F.S.); (L.Y.X.L.); (C.W.T.); (L.H.); (C.S.T.)
| | - Liangxing Hu
- Centre for Micro- and Nano-Electronics (CMNE), School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Ave, Singapore 639798, Singapore; (C.F.S.); (L.Y.X.L.); (C.W.T.); (L.H.); (C.S.T.)
| | - Philippe Coquet
- CNRS-NTU-THALES Research Alliances/UMI 3288, Research Techno Plaza, 50 Nanyang Ave, Border X Block, Level 6, Singapore 637553, Singapore; (J.W.); (S.C.K.G.); (P.C.); (H.L.)
- Institut d’Electronique, de Micro Electronique et de Nanotechnologie (IEMN), CNRS UMR 8520-Université de Lille, 59650 Villeneuve d’Ascq, France
| | - Hong Li
- CNRS-NTU-THALES Research Alliances/UMI 3288, Research Techno Plaza, 50 Nanyang Ave, Border X Block, Level 6, Singapore 637553, Singapore; (J.W.); (S.C.K.G.); (P.C.); (H.L.)
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Ave, Singapore 639798, Singapore
| | - Chuan Seng Tan
- Centre for Micro- and Nano-Electronics (CMNE), School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Ave, Singapore 639798, Singapore; (C.F.S.); (L.Y.X.L.); (C.W.T.); (L.H.); (C.S.T.)
| | - Beng Kang Tay
- Centre for Micro- and Nano-Electronics (CMNE), School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Ave, Singapore 639798, Singapore; (C.F.S.); (L.Y.X.L.); (C.W.T.); (L.H.); (C.S.T.)
- CNRS-NTU-THALES Research Alliances/UMI 3288, Research Techno Plaza, 50 Nanyang Ave, Border X Block, Level 6, Singapore 637553, Singapore; (J.W.); (S.C.K.G.); (P.C.); (H.L.)
- Correspondence:
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9
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Abstract
As a novel class of two-dimensional materials, MXene has provoked tremendous progress for various applications in functional devices. Here, we pioneer a preliminary understanding on the field emission behavior of MXene for the first time. Ti3C2 paper is fabricated by using facile filtration method, and multiple vertical sheets appear on the surface of MXene paper with high electrical conductivity (2.93 × 105 S m-1) and low work function (3.77 eV). The field electron emission performance and electric field distribution on MXene emitters are measured and simulated under planar and standing conditions. Both emitter conditions exhibit stable, uniform electron emission pattern, and the standing emitter achieves high emission current density of 59 mA cm-2 under 7.5 V μm-1. This work demonstrates the feasibility of MXene as cold electron source, establishing a preliminary foundation for its applications in field emission-based devices.
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Affiliation(s)
- Jiangtao Chen
- Laboratory of Clean Energy Chemistry and Materials, State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, People's Republic of China
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10
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He Y, Tang P, Hu Z, He Q, Zhu C, Wang L, Zeng Q, Golani P, Gao G, Fu W, Huang Z, Gao C, Xia J, Wang X, Wang X, Zhu C, Ramasse QM, Zhang A, An B, Zhang Y, Martí-Sánchez S, Morante JR, Wang L, Tay BK, Yakobson BI, Trampert A, Zhang H, Wu M, Wang QJ, Arbiol J, Liu Z. Engineering grain boundaries at the 2D limit for the hydrogen evolution reaction. Nat Commun 2020; 11:57. [PMID: 31896753 PMCID: PMC6940382 DOI: 10.1038/s41467-019-13631-2] [Citation(s) in RCA: 78] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 11/01/2019] [Indexed: 11/17/2022] Open
Abstract
Atom-thin transition metal dichalcogenides (TMDs) have emerged as fascinating materials and key structures for electrocatalysis. So far, their edges, dopant heteroatoms and defects have been intensively explored as active sites for the hydrogen evolution reaction (HER) to split water. However, grain boundaries (GBs), a key type of defects in TMDs, have been overlooked due to their low density and large structural variations. Here, we demonstrate the synthesis of wafer-size atom-thin TMD films with an ultra-high-density of GBs, up to ~1012 cm-2. We propose a climb and drive 0D/2D interaction to explain the underlying growth mechanism. The electrocatalytic activity of the nanograin film is comprehensively examined by micro-electrochemical measurements, showing an excellent hydrogen-evolution performance (onset potential: -25 mV and Tafel slope: 54 mV dec-1), thus indicating an intrinsically high activation of the TMD GBs.
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Affiliation(s)
- Yongmin He
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
- Center for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering & The Photonics Institute, Nanyang Technological University, Singapore, 639798, Singapore
| | - Pengyi Tang
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona, 08193, Catalonia, Spain
- Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, Sant Adrià del Besòs, Barcelona, 08930, Catalonia, Spain
| | - Zhili Hu
- College of Aerospace Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China
- Department of Materials Science and NanoEngineering, Rice University, Houston, TX, 77005, USA
| | - Qiyuan He
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Chao Zhu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Luqing Wang
- Department of Materials Science and NanoEngineering, Rice University, Houston, TX, 77005, USA
| | - Qingsheng Zeng
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Prafful Golani
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Guanhui Gao
- Paul-Drude-Institut für Festkörperelektronik Leibniz-Institut im Forschungsverbund Berlin Hausvogteiplatz, 5-7, 10117, Berlin, Germany
| | - Wei Fu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Zhiqi Huang
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Caitian Gao
- Centre for Micro-/Nano-electronics (NOVITAS), School of Electrical & Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Juan Xia
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Xingli Wang
- CNRS-International-NTU-THALES Research Alliance, Nanyang Technological University, Singaproe, 637553, Singapore
| | - Xuewen Wang
- Institute of Flexible Electronics, Northwestern Polytechnical University, Xi'an, 710072, China
| | - Chao Zhu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Quentin M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus, Keckwick Lane, Daresbury, WA44AD, UK
- School of Chemical and Process Engineering, University of Leeds, Leeds, LS29JT, UK
| | - Ao Zhang
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Boxing An
- College of Materials Science and Engineering, Beijing University of Technology, Beijing, 100124, People's Republic of China
| | - Yongzhe Zhang
- College of Materials Science and Engineering, Beijing University of Technology, Beijing, 100124, People's Republic of China
| | - Sara Martí-Sánchez
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona, 08193, Catalonia, Spain
| | - Joan Ramon Morante
- Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, Sant Adrià del Besòs, Barcelona, 08930, Catalonia, Spain
| | - Liang Wang
- School of Environmental and Chemical Engineering, Shanghai University, Shanghai, 200444, China
| | - Beng Kang Tay
- CNRS-International-NTU-THALES Research Alliance, Nanyang Technological University, Singaproe, 637553, Singapore
| | - Boris I Yakobson
- Department of Materials Science and NanoEngineering, Rice University, Houston, TX, 77005, USA
| | - Achim Trampert
- Paul-Drude-Institut für Festkörperelektronik Leibniz-Institut im Forschungsverbund Berlin Hausvogteiplatz, 5-7, 10117, Berlin, Germany
| | - Hua Zhang
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China
| | - Minghong Wu
- School of Environmental and Chemical Engineering, Shanghai University, Shanghai, 200444, China.
| | - Qi Jie Wang
- Center for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering & The Photonics Institute, Nanyang Technological University, Singapore, 639798, Singapore.
- CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, Singapore, 637553, Singapore.
| | - Jordi Arbiol
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona, 08193, Catalonia, Spain.
- ICREA, Pg. Lluís Companys 23, Barcelona, 08010, Catalonia, Spain.
| | - Zheng Liu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore.
- Centre for Micro-/Nano-electronics (NOVITAS), School of Electrical & Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore.
- CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, Singapore, 637553, Singapore.
- Environmental Chemistry and Materials Centre, Nanyang Environment and Water Research Institute, Singapore, Singapore.
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11
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Shan H, Yu Y, Wang X, Luo Y, Zu S, Du B, Han T, Li B, Li Y, Wu J, Lin F, Shi K, Tay BK, Liu Z, Zhu X, Fang Z. Direct observation of ultrafast plasmonic hot electron transfer in the strong coupling regime. Light Sci Appl 2019; 8:9. [PMID: 30651984 PMCID: PMC6333624 DOI: 10.1038/s41377-019-0121-6] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 01/03/2019] [Accepted: 01/03/2019] [Indexed: 05/22/2023]
Abstract
Achieving strong coupling between plasmonic oscillators can significantly modulate their intrinsic optical properties. Here, we report the direct observation of ultrafast plasmonic hot electron transfer from an Au grating array to an MoS2 monolayer in the strong coupling regime between localized surface plasmons (LSPs) and surface plasmon polaritons (SPPs). By means of femtosecond pump-probe spectroscopy, the measured hot electron transfer time is approximately 40 fs with a maximum external quantum yield of 1.65%. Our results suggest that strong coupling between LSPs and SPPs has synergetic effects on the generation of plasmonic hot carriers, where SPPs with a unique nonradiative feature can act as an 'energy recycle bin' to reuse the radiative energy of LSPs and contribute to hot carrier generation. Coherent energy exchange between plasmonic modes in the strong coupling regime can further enhance the vertical electric field and promote the transfer of hot electrons between the Au grating and the MoS2 monolayer. Our proposed plasmonic strong coupling configuration overcomes the challenge associated with utilizing hot carriers and is instructive in terms of improving the performance of plasmonic opto-electronic devices.
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Affiliation(s)
- Hangyong Shan
- School of Physics, State Key Lab for Mesoscopic Physics; Academy for Advanced Interdisciplinary Studies; Collaborative Innovation Center of Quantum Matter, Peking University, 100871 Beijing, China
| | - Ying Yu
- School of Physics, State Key Lab for Mesoscopic Physics; Academy for Advanced Interdisciplinary Studies; Collaborative Innovation Center of Quantum Matter, Peking University, 100871 Beijing, China
| | - Xingli Wang
- CNRS International-NTU-Thales Research Alliance (CINTRA), Nanyang Technological University, Singapore, 637553 Singapore
| | - Yang Luo
- School of Physics, State Key Lab for Mesoscopic Physics; Academy for Advanced Interdisciplinary Studies; Collaborative Innovation Center of Quantum Matter, Peking University, 100871 Beijing, China
| | - Shuai Zu
- School of Physics, State Key Lab for Mesoscopic Physics; Academy for Advanced Interdisciplinary Studies; Collaborative Innovation Center of Quantum Matter, Peking University, 100871 Beijing, China
| | - Bowen Du
- School of Physics, State Key Lab for Mesoscopic Physics; Academy for Advanced Interdisciplinary Studies; Collaborative Innovation Center of Quantum Matter, Peking University, 100871 Beijing, China
| | - Tianyang Han
- School of Physics, State Key Lab for Mesoscopic Physics; Academy for Advanced Interdisciplinary Studies; Collaborative Innovation Center of Quantum Matter, Peking University, 100871 Beijing, China
| | - Bowen Li
- School of Physics, State Key Lab for Mesoscopic Physics; Academy for Advanced Interdisciplinary Studies; Collaborative Innovation Center of Quantum Matter, Peking University, 100871 Beijing, China
| | - Yu Li
- School of Physics, State Key Lab for Mesoscopic Physics; Academy for Advanced Interdisciplinary Studies; Collaborative Innovation Center of Quantum Matter, Peking University, 100871 Beijing, China
| | - Jiarui Wu
- School of Physics, State Key Lab for Mesoscopic Physics; Academy for Advanced Interdisciplinary Studies; Collaborative Innovation Center of Quantum Matter, Peking University, 100871 Beijing, China
| | - Feng Lin
- School of Physics, State Key Lab for Mesoscopic Physics; Academy for Advanced Interdisciplinary Studies; Collaborative Innovation Center of Quantum Matter, Peking University, 100871 Beijing, China
| | - Kebin Shi
- School of Physics, State Key Lab for Mesoscopic Physics; Academy for Advanced Interdisciplinary Studies; Collaborative Innovation Center of Quantum Matter, Peking University, 100871 Beijing, China
| | - Beng Kang Tay
- CNRS International-NTU-Thales Research Alliance (CINTRA), Nanyang Technological University, Singapore, 637553 Singapore
- Centre for Micro-/Nano-Electronics (NOVITAS), School of Electrical and Electronic Engineering; Centre for Programmed Materials, School of Materials Science and Engineering, Nanyang Technological University, Singapore, 637553 Singapore
| | - Zheng Liu
- CNRS International-NTU-Thales Research Alliance (CINTRA), Nanyang Technological University, Singapore, 637553 Singapore
- Centre for Micro-/Nano-Electronics (NOVITAS), School of Electrical and Electronic Engineering; Centre for Programmed Materials, School of Materials Science and Engineering, Nanyang Technological University, Singapore, 637553 Singapore
| | - Xing Zhu
- School of Physics, State Key Lab for Mesoscopic Physics; Academy for Advanced Interdisciplinary Studies; Collaborative Innovation Center of Quantum Matter, Peking University, 100871 Beijing, China
| | - Zheyu Fang
- School of Physics, State Key Lab for Mesoscopic Physics; Academy for Advanced Interdisciplinary Studies; Collaborative Innovation Center of Quantum Matter, Peking University, 100871 Beijing, China
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12
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Fu Q, Zhu C, Zhao X, Wang X, Chaturvedi A, Zhu C, Wang X, Zeng Q, Zhou J, Liu F, Tay BK, Zhang H, Pennycook SJ, Liu Z. Ultrasensitive 2D Bi 2 O 2 Se Phototransistors on Silicon Substrates. Adv Mater 2019; 31:e1804945. [PMID: 30417479 DOI: 10.1002/adma.201804945] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 09/28/2018] [Indexed: 05/07/2023]
Abstract
2D materials are considered as intriguing building blocks for next-generation optoelectronic devices. However, their photoresponse performance still needs to be improved for practical applications. Here, ultrasensitive 2D phototransistors are reported employing chemical vapor deposition (CVD)-grown 2D Bi2 O2 Se transferred onto silicon substrates with a noncorrosive transfer method. The as-transferred Bi2 O2 Se preserves high quality in contrast to the serious quality degradation in hydrofluoric-acid-assisted transfer. The phototransistors show a responsivity of 3.5 × 104 A W-1 , a photoconductive gain of more than 104 , and a time response in the order of sub-millisecond. With back gating of the silicon substrate, the dark current can be reduced to several pA. This yields an ultrahigh sensitivity with a specific detectivity of 9.0 × 1013 Jones, which is one of the highest values among 2D material photodetectors and two orders of magnitude higher than that of other CVD-grown 2D materials. The high performance of the phototransistor shown here together with the developed unique transfer technique are promising for the development of novel 2D-material-based optoelectronic applications as well as integrating with state-of-the-art silicon photonic and electronic technologies.
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Affiliation(s)
- Qundong Fu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Chao Zhu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Xiaoxu Zhao
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117575, Singapore
| | - Xingli Wang
- CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, Singapore, 637553, Singapore
| | - Apoorva Chaturvedi
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Chao Zhu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Xiaowei Wang
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Qingsheng Zeng
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Jiadong Zhou
- 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
- School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Beng Kang Tay
- CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, Singapore, 637553, Singapore
| | - Hua Zhang
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Stephen J Pennycook
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117575, Singapore
| | - Zheng Liu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
- CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, Singapore, 637553, Singapore
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13
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Fu Q, Zhu C, Zhao X, Wang X, Chaturvedi A, Zhu C, Wang X, Zeng Q, Zhou J, Liu F, Tay BK, Zhang H, Pennycook SJ, Liu Z. Ultrasensitive 2D Bi 2 O 2 Se Phototransistors on Silicon Substrates. Adv Mater 2018. [PMID: 30417479 DOI: 10.1002/adma.201804945.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
2D materials are considered as intriguing building blocks for next-generation optoelectronic devices. However, their photoresponse performance still needs to be improved for practical applications. Here, ultrasensitive 2D phototransistors are reported employing chemical vapor deposition (CVD)-grown 2D Bi2 O2 Se transferred onto silicon substrates with a noncorrosive transfer method. The as-transferred Bi2 O2 Se preserves high quality in contrast to the serious quality degradation in hydrofluoric-acid-assisted transfer. The phototransistors show a responsivity of 3.5 × 104 A W-1 , a photoconductive gain of more than 104 , and a time response in the order of sub-millisecond. With back gating of the silicon substrate, the dark current can be reduced to several pA. This yields an ultrahigh sensitivity with a specific detectivity of 9.0 × 1013 Jones, which is one of the highest values among 2D material photodetectors and two orders of magnitude higher than that of other CVD-grown 2D materials. The high performance of the phototransistor shown here together with the developed unique transfer technique are promising for the development of novel 2D-material-based optoelectronic applications as well as integrating with state-of-the-art silicon photonic and electronic technologies.
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Affiliation(s)
- Qundong Fu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Chao Zhu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Xiaoxu Zhao
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117575, Singapore
| | - Xingli Wang
- CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, Singapore, 637553, Singapore
| | - Apoorva Chaturvedi
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Chao Zhu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Xiaowei Wang
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Qingsheng Zeng
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Jiadong Zhou
- 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.,School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Beng Kang Tay
- CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, Singapore, 637553, Singapore
| | - Hua Zhang
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Stephen J Pennycook
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117575, Singapore
| | - Zheng Liu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore.,CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, Singapore, 637553, Singapore
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14
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Maurice A, Bodelot L, Tay BK, Lebental B. Controlled, Low-Temperature Nanogap Propagation in Graphene Using Femtosecond Laser Patterning. Small 2018; 14:e1801348. [PMID: 29971912 DOI: 10.1002/smll.201801348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 06/05/2018] [Indexed: 06/08/2023]
Abstract
Graphene nanogap systems are promising research tools for molecular electronics, memories, and nanodevices. Here, a way to control the propagation of nanogaps in monolayer graphene during electroburning is demonstrated. A tightly focused femtosecond laser beam is used to induce defects in graphene according to selected patterns. It is shown that, contrary to the pristine graphene devices where nanogap position and shape are uncontrolled, the nanogaps in prepatterned devices propagate along the defect line created by the femtosecond laser. Using passive voltage contrast combined with atomic force microscopy, the reproducibility of the process with a 92% success rate over 26 devices is confirmed. Coupling in situ infrared thermography and finite element analysis yields a real-time estimation of the device temperature during electrical loading. The controlled nanogap formation occurs well below 50 °C when the defect density is high enough. In the perspective of graphene-based circuit fabrication, the availability of a cold electroburning process is critical to preserve the full circuit from thermal damage.
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Affiliation(s)
- Ange Maurice
- NOVITAS, Nanoelectronics Center of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore
- CINTRA, CNRS International NTU THALES Research Alliance, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore, 637553, Singapore
| | - Laurence Bodelot
- Laboratoire de Mécanique des Solides, Ecole Polytechnique, CNRS, Université Paris-Saclay, Palaiseau, 91128, France
| | - Beng Kang Tay
- NOVITAS, Nanoelectronics Center of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore
- CINTRA, CNRS International NTU THALES Research Alliance, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore, 637553, Singapore
| | - Bérengère Lebental
- LPICM, CNRS, Ecole Polytechnique, Université Paris-Saclay, Palaiseau, 91128, France
- Université Paris-Est, IFSTTAR, COSYS, Marne-La-Vallée, 77447, France
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15
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Lim YD, Grapov D, Hu L, Kong Q, Tay BK, Labunov V, Miao J, Coquet P, Aditya S. Enhanced field emission properties of carbon nanotube bundles confined in SiO 2 pits. Nanotechnology 2018; 29:075205. [PMID: 29239308 DOI: 10.1088/1361-6528/aaa1bb] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
It has been widely reported that carbon nanotubes (CNTs) exhibit superior field emission (FE) properties due to their high aspect ratios and unique structural properties. Among the various types of CNTs, random growth CNTs exhibit promising FE properties due to their reduced inter-tube screening effect. However, growing random growth CNTs on individual catalyst islands often results in spread out CNT bundles, which reduces overall field enhancement. In this study, significant improvement in FE properties in CNT bundles is demonstrated by confining them in microfabricated SiO2 pits. Growing CNT bundles in narrow (0.5 μm diameter and 2 μm height) SiO2 pits achieves FE current density of 1-1.4 A cm-2, which is much higher than for freestanding CNT bundles (76.9 mA cm-2). From the Fowler Nordheim plots, confined CNT bundles show a higher field enhancement factor. This improvement can be attributed to the reduced bundle diameter by SiO2 pit confinement, which yields bundles with higher aspect ratios. Combining the obtained outcomes, it can be conclusively summarized that confining CNTs in SiO2 pits yields higher FE current density due to the higher field enhancement of confined CNTs.
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Affiliation(s)
- Yu Dian Lim
- Centre for Micro-/Nano-electronics (NOVITAS), School of Electrical and Electronics Engineering, Nanyang Technological University, 50 Nanyang Avenue 639798, Singapore
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16
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Lim YD, Hu L, Xia X, Ali Z, Wang S, Tay BK, Aditya S, Miao J. Field emission properties of SiO 2-wrapped CNT field emitter. Nanotechnology 2018; 29:015202. [PMID: 29083996 DOI: 10.1088/1361-6528/aa96ed] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Carbon nanotubes (CNTs) exhibit unstable field emission (FE) behavior with low reliability due to uneven heights of as-grown CNTs. It has been reported that a mechanically polished SiO2-wrapped CNT field emitter gives consistent FE performance due to its uniform CNT heights. However, there are still a lack of studies on the comparison between the FE properties of freestanding and SiO2-wrapped CNTs. In this study, we have performed a comparative study on the FE properties of freestanding and SiO2-wrapped CNT field emitters. From the FE measurements, freestanding CNT field emitter requires lower applied voltage of 5.5 V μm-1 to achieve FE current density of 22 mA cm-2; whereas SiO2-wrapped field emitter requires 8.5 V μm-1 to achieve the same current density. This can be attributed to the lower CNT tip electric field of CNTs embedded in SiO2, as obtained from the electric field simulation. Nevertheless, SiO2-wrapped CNTs show higher consistency in FE current than freestanding CNTs. Under repeated FE measurement, SiO2-wrapped CNT field emitter achieves consistent FE behavior from the 1st voltage sweep, whereas freestanding field emitter only achieved consistent FE performance after 3rd voltage sweep. At the same time, SiO2-wrapped CNTs exhibit better emission stability than freestanding CNTs over 4000 s continuous emission.
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Affiliation(s)
- Yu Dian Lim
- Nanoelectronics Centre of Excellence (NOVITAS), School of Electrical and Electronics Engineering, Nanyang Technological University. 50 Nanyang Avenue 639798, Singapore
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17
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Lim YD, Avramchuck AV, Grapov D, Tan CW, Tay BK, Aditya S, Labunov V. Enhanced Carbon Nanotubes Growth Using Nickel/Ferrocene-Hybridized Catalyst. ACS Omega 2017; 2:6063-6071. [PMID: 31457855 PMCID: PMC6644565 DOI: 10.1021/acsomega.7b00858] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2017] [Accepted: 09/07/2017] [Indexed: 06/07/2023]
Abstract
Tall, crystalline carbon nanotubes (CNTs) are desired to successfully integrate them in various applications. As the crystallinity of CNTs improves with increasing growth temperatures, higher growth temperatures are required to obtain crystalline CNTs. However, in a typical chemical vapor deposition (CVD) process, CNT growth rate reduces when the growth temperature exceeds a specific level due to the degradation of the catalyst particles. In this study, we have demonstrated the improved catalytic activity of nickel/ferrocene-hybridized catalyst as compared to sole ferrocene catalyst. To demonstrate this, CNTs are grown on bare silicon (Si) as well as nickel (Ni) catalyst-deposited substrates using volatile catalyst source (ferrocene/xylene) CVD at the growth temperatures ranging from 790 to 880 °C. It was found that CNTs grown on bare Si substrate experience a reduction in height at growth temperature above 860 °C, whereas the CNTs grown on 10 nm Ni catalyst-deposited substrates experience continuous increase in height as the temperature increases from 790 to 880 °C. The enhancement in the height of CNTs by the addition of Ni catalyst is also demonstrated on 5, 20, and 30 nm Ni layers. The examination of CNTs using electron microscopy and Raman spectra shows that the additional Ni catalyst source improves the CNT growth rates and crystallinity, yielding taller CNTs with a high degree of structural crystallinity.
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Affiliation(s)
- Yu Dian Lim
- School
of Electrical and Electronics Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore
| | - Alexander Vasiliyvich Avramchuck
- Micro-
and Nanoelectronics Department, Belarusian
State University of Informatics and Radioelectronics, vulica Pietrusia Broŭki 6, 220013 Minsk, Belarus
| | - Dmitry Grapov
- Micro-
and Nanoelectronics Department, Belarusian
State University of Informatics and Radioelectronics, vulica Pietrusia Broŭki 6, 220013 Minsk, Belarus
| | - Chong Wei Tan
- School
of Electrical and Electronics Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore
| | - Beng Kang Tay
- School
of Electrical and Electronics Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore
| | - Sheel Aditya
- School
of Electrical and Electronics Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore
| | - Vladimir Labunov
- Micro-
and Nanoelectronics Department, Belarusian
State University of Informatics and Radioelectronics, vulica Pietrusia Broŭki 6, 220013 Minsk, Belarus
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18
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Legrand D, Le Cunff LO, Bruyant A, Salas-Montiel R, Liu Z, Tay BK, Maurer T, Bachelot R. Surface plasmons in suspended graphene: launching with in-plane gold nanoantenna and propagation properties. Opt Express 2017; 25:17306-17321. [PMID: 28789223 DOI: 10.1364/oe.25.017306] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 06/15/2017] [Indexed: 06/07/2023]
Abstract
Graphene physics and plasmonics are two fields which, once combined, promise a variety of exciting applications. One of those applications is the integration of active nano-optoelectronic devices in electronic systems, using the fact that plasmons in graphene are tunable, highly confined and weakly damped. A crucial challenge remains before achieving these active devices: finding a platform enabling a high propagation of Graphene Plasmons Polaritons (GPPs). Suspended graphene presenting ultrahigh electron mobility has given rise to increasing interest. We numerically studied the plasmonic properties of suspended graphene. We propose a hybrid configuration and a set of conditions to launch graphene plasmons via an in-plane gold nanoantenna, for micrometric propagation of surface plasmons in suspended graphene. Finally, we propose a realistic optoelectronic device based on the use of suspended graphene.
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19
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Chow WL, Yu P, Liu F, Hong J, Wang X, Zeng Q, Hsu CH, Zhu C, Zhou J, Wang X, Xia J, Yan J, Chen Y, Wu D, Yu T, Shen Z, Lin H, Jin C, Tay BK, Liu Z. High Mobility 2D Palladium Diselenide Field-Effect Transistors with Tunable Ambipolar Characteristics. Adv Mater 2017; 29. [PMID: 28370566 DOI: 10.1002/adma.201602969] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 02/15/2017] [Indexed: 05/11/2023]
Abstract
Due to the intriguing optical and electronic properties, 2D materials have attracted a lot of interest for the electronic and optoelectronic applications. Identifying new promising 2D materials will be rewarding toward the development of next generation 2D electronics. Here, palladium diselenide (PdSe2 ), a noble-transition metal dichalcogenide (TMDC), is introduced as a promising high mobility 2D material into the fast growing 2D community. Field-effect transistors (FETs) based on ultrathin PdSe2 show intrinsic ambipolar characteristic. The polarity of the FET can be tuned. After vacuum annealing, the authors find PdSe2 to exhibit electron-dominated transport with high mobility (µe (max) = 216 cm2 V-1 s-1 ) and on/off ratio up to 103 . Hole-dominated-transport PdSe2 can be obtained by molecular doping using F4 -TCNQ. This pioneer work on PdSe2 will spark interests in the less explored regime of noble-TMDCs.
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Affiliation(s)
- Wai Leong Chow
- Centre for Micro-/Nano-electronics (NOVITAS), School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
- CINTRA UMI CNRS/NTU/THALES, Singapore, 637553, Singapore
| | - Peng Yu
- Centre for Programmed Materials, School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Fucai Liu
- Centre for Programmed Materials, School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Jinhua Hong
- State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang, 310027, P. R. China
| | - Xingli Wang
- Centre for Micro-/Nano-electronics (NOVITAS), School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
- CINTRA UMI CNRS/NTU/THALES, Singapore, 637553, Singapore
- State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang, 310027, P. R. China
| | - Qingsheng Zeng
- Centre for Programmed Materials, School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Chuang-Han Hsu
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Chao Zhu
- Centre for Programmed Materials, School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Jiadong Zhou
- State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang, 310027, P. R. China
| | - Xiaowei Wang
- State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang, 310027, P. R. China
| | - Juan Xia
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 639798, Singapore
| | - Jiaxu Yan
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 639798, Singapore
| | - Yu Chen
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 639798, Singapore
| | - Di Wu
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Ting Yu
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 639798, Singapore
| | - Zexiang Shen
- CINTRA UMI CNRS/NTU/THALES, Singapore, 637553, Singapore
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 639798, Singapore
| | - Hsin Lin
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Chuanhong Jin
- State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang, 310027, P. R. China
| | - Beng Kang Tay
- Centre for Micro-/Nano-electronics (NOVITAS), School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
- CINTRA UMI CNRS/NTU/THALES, Singapore, 637553, Singapore
| | - Zheng Liu
- CINTRA UMI CNRS/NTU/THALES, Singapore, 637553, Singapore
- Centre for Programmed Materials, School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
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20
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Shen J, Li X, Wan L, Liang K, Tay BK, Kong L, Yan X. An Asymmetric Supercapacitor with Both Ultra-High Gravimetric and Volumetric Energy Density Based on 3D Ni(OH) 2/MnO 2@Carbon Nanotube and Activated Polyaniline-Derived Carbon. ACS Appl Mater Interfaces 2017; 9:668-676. [PMID: 27936554 DOI: 10.1021/acsami.6b12370] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Development of a supercapacitor device with both high gravimetric and volumetric energy density is one of the most important requirements for their practical application in energy storage/conversion systems. Currently, improvement of the gravimetric/volumetric energy density of a supercapacitor is restricted by the insufficient utilization of positive materials at high loading density and the inferior capacitive behavior of negative electrodes. To solve these problems, we elaborately designed and prepared a 3D core-shell structured Ni(OH)2/MnO2@carbon nanotube (CNT) composite via a facile solvothermal process by using the thermal chemical vapor deposition grown-CNTs as support. Owing to the superiorities of core-shell architecture in improving the service efficiency of pseudocapacitive materials at high loading density, the prepared Ni(OH)2/MnO2@CNT electrode demonstrated a high capacitance value of 2648 F g-1 (1 A g-1) at a high loading density of 6.52 mg cm-2. Coupled with high-performance activated polyaniline-derived carbon (APDC, 400 F g-1 at 1 A g-1), the assembled Ni(OH)2/MnO2@CNT//APDC asymmetric device delivered both high gravimetric and volumetric energy density (126.4 Wh kg-1 and 10.9 mWh cm-3, respectively), together with superb rate performance and cycling lifetime. Moreover, we demonstrate an effective approach for building a high-performance supercapacitor with high gravimetric/volumetric energy density.
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Affiliation(s)
- Juanjuan Shen
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metal, Lanzhou University of Technology , Lanzhou 730050, P. R. China
- Laboratory of Clean Energy Chemistry and Materials, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences , Lanzhou 730000, P. R. China
- University of Chinese Academy of Science , Beijing 100080, P. R. China
| | - Xiaocheng Li
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metal, Lanzhou University of Technology , Lanzhou 730050, P. R. China
- Laboratory of Clean Energy Chemistry and Materials, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences , Lanzhou 730000, P. R. China
| | - Liu Wan
- Laboratory of Clean Energy Chemistry and Materials, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences , Lanzhou 730000, P. R. China
| | - Kun Liang
- School of Electrical & Electronic Engineering, Nanyang Technological University , 50 Nanyang Avenue, Singapore 639798
| | - Beng Kang Tay
- School of Electrical & Electronic Engineering, Nanyang Technological University , 50 Nanyang Avenue, Singapore 639798
| | - Lingbin Kong
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metal, Lanzhou University of Technology , Lanzhou 730050, P. R. China
| | - Xingbin Yan
- Laboratory of Clean Energy Chemistry and Materials, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences , Lanzhou 730000, P. R. China
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21
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Yang P, Chao D, Zhu C, Xia X, Zhang Y, Wang X, Sun P, Tay BK, Shen ZX, Mai W, Fan HJ. Ultrafast-Charging Supercapacitors Based on Corn-Like Titanium Nitride Nanostructures. Adv Sci (Weinh) 2016; 3:1500299. [PMID: 27774405 PMCID: PMC5057334 DOI: 10.1002/advs.201500299] [Citation(s) in RCA: 39] [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] [Received: 09/04/2015] [Indexed: 05/29/2023]
Abstract
Ultrahigh rates realized by ALD-made TiN. The symmetric full-cell supercapacitors deliver a typical capacitance of 20.7 F cm-3 at a scan rate of 1 V s-1, and retain 4.3 F cm-3 at high rate of 100 V s-1. The devices can be charged and discharged for 20 000 cycles with negligible capacitance loss and with an ultralow self-discharge current (≈1 μA).
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Affiliation(s)
- Peihua Yang
- Department of Physics and Siyuan Laboratory Jinan University Guangzhou Guangdong 510632 P.R. China; School of Physical and Mathematical Sciences Nanyang Technological University Singapore 637371 Singapore
| | - Dongliang Chao
- School of Physical and Mathematical Sciences Nanyang Technological University Singapore 637371 Singapore
| | - Changrong Zhu
- School of Physical and Mathematical Sciences Nanyang Technological University Singapore 637371 Singapore
| | - Xinhui Xia
- School of Physical and Mathematical Sciences Nanyang Technological University Singapore 637371 Singapore
| | - Yongqi Zhang
- School of Physical and Mathematical Sciences Nanyang Technological University Singapore 637371 Singapore
| | - Xingli Wang
- School of Electrical and Electronic Engineering Nanyang Technological University Singapore 639798 Singapore
| | - Peng Sun
- Department of Physics and Siyuan Laboratory Jinan University Guangzhou Guangdong 510632 P.R. China
| | - Beng Kang Tay
- School of Electrical and Electronic Engineering Nanyang Technological University Singapore 639798 Singapore
| | - Ze Xiang Shen
- School of Physical and Mathematical Sciences Nanyang Technological University Singapore 637371 Singapore
| | - Wenjie Mai
- Department of Physics and Siyuan Laboratory Jinan University Guangzhou Guangdong 510632 P.R. China
| | - Hong Jin Fan
- School of Physical and Mathematical Sciences Nanyang Technological University Singapore 637371 Singapore
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22
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Loisel L, Florea I, Cojocaru CS, Tay BK, Lebental B. Oxidation-Based Continuous Laser Writing in Vertical Nano-Crystalline Graphite Thin Films. Sci Rep 2016; 6:26224. [PMID: 27194181 PMCID: PMC4872136 DOI: 10.1038/srep26224] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 04/22/2016] [Indexed: 11/09/2022] Open
Abstract
Nano and femtosecond laser writing are becoming very popular techniques for patterning carbon-based materials, as they are single-step processes enabling the drawing of complex shapes without photoresist. However, pulsed laser writing requires costly laser sources and is known to cause damages to the surrounding material. By comparison, continuous-wave lasers are cheap, stable and provide energy at a more moderate rate. Here, we show that a continuous-wave laser may be used to pattern vertical nano-crystalline graphite thin films with very few macroscale defects. Moreover, a spatially resolved study of the impact of the annealing to the crystalline structure and to the oxygen ingress in the film is provided: amorphization, matter removal and high oxygen content at the center of the beam; sp2 clustering and low oxygen content at its periphery. These data strongly suggest that amorphization and matter removal are controlled by carbon oxidation. The simultaneous occurrence of oxidation and amorphization results in a unique evolution of the Raman spectra as a function of annealing time, with a decrease of the I(D)/I(G) values but an upshift of the G peak frequency.
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Affiliation(s)
- Loïc Loisel
- CINTRA CNRS/NTU/Thalès, UMI 3288, 50 Nanyang Drive, Singapore.,School of Electrical and Electronics Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore.,LPICM, CNRS, Ecole Polytechnique, Université Paris Saclay, 91128, Palaiseau, France
| | - Ileana Florea
- LPICM, CNRS, Ecole Polytechnique, Université Paris Saclay, 91128, Palaiseau, France
| | | | - Beng Kang Tay
- CINTRA CNRS/NTU/Thalès, UMI 3288, 50 Nanyang Drive, Singapore.,School of Electrical and Electronics Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore
| | - Bérengère Lebental
- LPICM, CNRS, Ecole Polytechnique, Université Paris Saclay, 91128, Palaiseau, France.,Université Paris-Est, IFSTTAR, 14-20 Bd Newton, Champs-sur-Marne, F-77447, Marne-la-Vallée, France
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23
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Niu L, Liu X, Cong C, Wu C, Wu D, Chang TR, Wang H, Zeng Q, Zhou J, Wang X, Fu W, Yu P, Fu Q, Najmaei S, Zhang Z, Yakobson BI, Tay BK, Zhou W, Jeng HT, Lin H, Sum TC, Jin C, He H, Yu T, Liu Z. Controlled Synthesis of Organic/Inorganic van der Waals Solid for Tunable Light-Matter Interactions. Adv Mater 2015; 27:7800-7808. [PMID: 26505987 DOI: 10.1002/adma.201503367] [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] [Received: 07/13/2015] [Revised: 08/29/2015] [Indexed: 06/05/2023]
Abstract
High-quality organic and inorganic van der Waals (vdW) solids are realized using methylammonium lead halide (CH3 NH3 PbI3 ) as the organic part (organic perovskite) and 2D inorganic monolayers as counterparts. By stacking on various 2D monolayers, the vdW solids exhibit dramatically different light emissions. Futhermore, organic/h-BN vdW solid arrays are patterned for red-light emission.
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Affiliation(s)
- Lin Niu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, Singapore, 639798, Singapore
| | - Xinfeng Liu
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore, 637371, Singapore
- National Center for Nanoscience and Technology, Beijing, 100190, China
| | - Chunxiao Cong
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore, 637371, Singapore
| | - Chunyang Wu
- State Key Laboratory of Silicon Materials and School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027, P. R. China
| | - Di Wu
- Centre for Advanced 2D Materials and Department of Physics, National University of Singapore, Singapore, Singapore, 117542, Singapore
| | - Tay Rong Chang
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - Hong Wang
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, Singapore, 639798, Singapore
| | - Qingsheng Zeng
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, Singapore, 639798, Singapore
| | - Jiadong Zhou
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, Singapore, 639798, Singapore
| | - Xingli Wang
- NOVITAS, Nanoelectronics Centre of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Wei Fu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, Singapore, 639798, Singapore
| | - Peng Yu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, Singapore, 639798, Singapore
| | - Qundong Fu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, Singapore, 639798, Singapore
| | - Sina Najmaei
- United States Army Research Laboratories, Sensors and Electron Devices Directorate, 2800 Powder Mill Road, Adelphi, MD, 20783, USA
| | - Zhuhua Zhang
- Department of Materials Science and Nanoengineering, Rice University, Houston, TX, 77005, USA
| | - Boris I Yakobson
- Department of Materials Science and Nanoengineering, Rice University, Houston, TX, 77005, USA
| | - Beng Kang Tay
- NOVITAS, Nanoelectronics Centre of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Wu Zhou
- Materials Science and Technology Division, Oak Ridge National Lab, Oak Ridge, TN, 37831, USA
| | - Horng Tay Jeng
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - Hsin Lin
- Centre for Advanced 2D Materials and Department of Physics, National University of Singapore, Singapore, Singapore, 117542, Singapore
| | - Tze Chien Sum
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore, 637371, Singapore
| | - Chuanhong Jin
- State Key Laboratory of Silicon Materials and School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027, P. R. China
| | - Haiyong He
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, Singapore, 639798, Singapore
| | - Ting Yu
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore, 637371, Singapore
| | - Zheng Liu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, Singapore, 639798, Singapore
- NOVITAS, Nanoelectronics Centre of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore
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24
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Yan J, Xia J, Wang X, Liu L, Kuo JL, Tay BK, Chen S, Zhou W, Liu Z, Shen ZX. Stacking-Dependent Interlayer Coupling in Trilayer MoS₂ with Broken Inversion Symmetry. Nano Lett 2015; 15:8155-61. [PMID: 26565932 DOI: 10.1021/acs.nanolett.5b03597] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The stacking configuration in few-layer two-dimensional (2D) materials results in different structural symmetries and layer-to-layer interactions, and hence it provides a very useful parameter for tuning their electronic properties. For example, ABA-stacking trilayer graphene remains semimetallic similar to that of monolayer, while ABC-stacking is predicted to be a tunable band gap semiconductor under an external electric field. Such stacking dependence resulting from many-body interactions has recently been the focus of intense research activities. Here we demonstrate that few-layer MoS2 samples grown by chemical vapor deposition with different stacking configurations (AA, AB for bilayer; AAB, ABB, ABA, AAA for trilayer) exhibit distinct coupling phenomena in both photoluminescence and Raman spectra. By means of ultralow-frequency (ULF) Raman spectroscopy, we demonstrate that the evolution of interlayer interaction with various stacking configurations correlates strongly with layer-breathing mode (LBM) vibrations. Our ab initio calculations reveal that the layer-dependent properties arise from both the spin-orbit coupling (SOC) and interlayer coupling in different structural symmetries. Such detailed understanding provides useful guidance for future spintronics fabrication using various stacked few-layer MoS2 blocks.
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Affiliation(s)
- Jiaxu Yan
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , Singapore 637371, Singapore
| | - Juan Xia
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , Singapore 637371, Singapore
| | - Xingli Wang
- NOVITAS, Nanoelectronics Centre of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University , Singapore 639798, Singapore
| | - Lei Liu
- State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences , Changchun 130033, P. R. China
| | - Jer-Lai Kuo
- Institute of Atomic and Molecular Sciences, Academia Sinica , Taipei 10617, Taiwan
| | - Beng Kang Tay
- NOVITAS, Nanoelectronics Centre of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University , Singapore 639798, Singapore
| | - Shoushun Chen
- School of Electrical and Electronic Engineering, Nanyang Technological University , Singapore 639798, Singapore
| | - Wu Zhou
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Zheng Liu
- NOVITAS, Nanoelectronics Centre of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University , Singapore 639798, Singapore
- School of Materials Science and Engineering, Nanyang Technological University , Singapore 639798, Singapore
| | - Ze Xiang Shen
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , Singapore 637371, Singapore
- Centre for Disruptive Photonic Technologies, Nanyang Technological University , Singapore 637371, Singapore
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25
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Zhu C, Yang P, Chao D, Wang X, Zhang X, Chen S, Tay BK, Huang H, Zhang H, Mai W, Fan HJ. All Metal Nitrides Solid-State Asymmetric Supercapacitors. Adv Mater 2015; 27:4566-71. [PMID: 26153405 DOI: 10.1002/adma.201501838] [Citation(s) in RCA: 130] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 05/20/2015] [Indexed: 05/26/2023]
Abstract
Two metal nitrides, TiN porous layers and Fe2 N nanoparticles, are grown uniformly with the assistance of atomic layer deposition on vertically aligned graphene nanosheets and used as the cathode and anode for solid-state supercapacitors, respectively. Full cells are constructed and show good flexibility, high-rate capability, and 98% capacitance retention after 20,000 cycles.
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Affiliation(s)
- Changrong Zhu
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore, Singapore
- Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, 638075, Singapore, Singapore
| | - Peihua Yang
- Department of Physics and Siyuan Laboratory, Jinan University, Guangzhou, 510632, P. R. China
| | - Dongliang Chao
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore, Singapore
| | - Xingli Wang
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore, Singapore
| | - Xiao Zhang
- School of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore
| | - Shi Chen
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore, Singapore
| | - Beng Kang Tay
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore, Singapore
| | - Hui Huang
- Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, 638075, Singapore, Singapore
| | - Hua Zhang
- School of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore
| | - Wenjie Mai
- Department of Physics and Siyuan Laboratory, Jinan University, Guangzhou, 510632, P. R. China
| | - Hong Jin Fan
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore, Singapore
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26
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Liu W, Lu C, Wang X, Tay RY, Tay BK. High-performance microsupercapacitors based on two-dimensional graphene/manganese dioxide/silver nanowire ternary hybrid film. ACS Nano 2015; 9:1528-1542. [PMID: 25560268 DOI: 10.1021/nn5060442] [Citation(s) in RCA: 76] [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] [Indexed: 06/04/2023]
Abstract
Microsupercapacitors (MSCs), as one type of significant power source or energy storage unit in microelectronic devices, have attracted more and more attention. However, how to reasonably design electrode structures and exploit the active materials to endow the MSCs with excellent performances in a limited surface area still remains a challenge. Here, a reduced graphene oxide (RGO)/manganese dioxide (MnO2)/silver nanowire (AgNW) ternary hybrid film (RGMA ternary hybrid film) is successfully fabricated by a facile vacuum filtration and subsequent thermal reduction, and is used directly as a binder-free electrode for MSCs. Additionally, a flexible, transparent, all-solid state RMGA-MSC is also built, and its electrochemical performance in an ionic liquid gel electrolyte are investigated in depth. Notably, the RGMA-MSCs display superior electrochemical properties, including exceptionally high rate capability (up to 50000 mV·s(-1)), high frequency response (very short corresponding time constant τ0 = 0.14 ms), and excellent cycle stability (90.3% of the initial capacitance after 6000 cycles in ionic liquid gel electrolyte). Importantly, the electrochemical performance of RGMA-MSCs shows a strong dependence on the geometric parameters including the interspace between adjacent fingers and the width of the finger of MSCs. These encouraging results may not only provide important references for the design and fabrication of high-performance MSCs, but also make the RGMA ternary hybrid film promising for the next generation film lithium ion batteries and other energy storage devices.
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Affiliation(s)
- Wenwen Liu
- Novitas, Nanoelectronics Center of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University , Singapore 639798, Singapore
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27
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Gong Y, Lin J, Wang X, Shi G, Lei S, Lin Z, Zou X, Ye G, Vajtai R, Yakobson BI, Terrones H, Terrones M, Tay BK, Lou J, Pantelides ST, Liu Z, Zhou W, Ajayan PM. Vertical and in-plane heterostructures from WS2/MoS2 monolayers. Nat Mater 2014; 13:1135-42. [PMID: 25262094 DOI: 10.1038/nmat4091] [Citation(s) in RCA: 858] [Impact Index Per Article: 85.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 08/20/2014] [Indexed: 04/14/2023]
Abstract
Layer-by-layer stacking or lateral interfacing of atomic monolayers has opened up unprecedented opportunities to engineer two-dimensional heteromaterials. Fabrication of such artificial heterostructures with atomically clean and sharp interfaces, however, is challenging. Here, we report a one-step growth strategy for the creation of high-quality vertically stacked as well as in-plane interconnected heterostructures of WS2/MoS2 via control of the growth temperature. Vertically stacked bilayers with WS2 epitaxially grown on top of the MoS2 monolayer are formed with preferred stacking order at high temperature. A strong interlayer excitonic transition is observed due to the type II band alignment and to the clean interface of these bilayers. Vapour growth at low temperature, on the other hand, leads to lateral epitaxy of WS2 on MoS2 edges, creating seamless and atomically sharp in-plane heterostructures that generate strong localized photoluminescence enhancement and intrinsic p-n junctions. The fabrication of heterostructures from monolayers, using simple and scalable growth, paves the way for the creation of unprecedented two-dimensional materials with exciting properties.
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Affiliation(s)
- Yongji Gong
- 1] Department of Chemistry, Rice University, Houston, Texas 77005, USA [2] Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA
| | - Junhao Lin
- 1] Materials Science and Technology Division, Oak Ridge National Lab, Oak Ridge, Tennessee 37831, USA [2] Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, USA
| | - Xingli Wang
- 1] School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 [2] School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798
| | - Gang Shi
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA
| | - Sidong Lei
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA
| | - Zhong Lin
- Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Xiaolong Zou
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA
| | - Gonglan Ye
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA
| | - Robert Vajtai
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA
| | - Boris I Yakobson
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA
| | - Humberto Terrones
- Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, Johnson-Rowland Science Center, 110 Eighth Street, Troy, New York 12180, USA
| | - Mauricio Terrones
- 1] Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, USA [2] Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA [3] Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA [4] Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Beng Kang Tay
- 1] School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 [2] School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798
| | - Jun Lou
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA
| | - Sokrates T Pantelides
- 1] Materials Science and Technology Division, Oak Ridge National Lab, Oak Ridge, Tennessee 37831, USA [2] Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, USA
| | - Zheng Liu
- 1] School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 [2] School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798
| | - Wu Zhou
- Materials Science and Technology Division, Oak Ridge National Lab, Oak Ridge, Tennessee 37831, USA
| | - Pulickel M Ajayan
- 1] Department of Chemistry, Rice University, Houston, Texas 77005, USA [2] Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA
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Wang X, Gong Y, Shi G, Chow WL, Keyshar K, Ye G, Vajtai R, Lou J, Liu Z, Ringe E, Tay BK, Ajayan PM. Chemical vapor deposition growth of crystalline monolayer MoSe2. ACS Nano 2014; 8:5125-5131. [PMID: 24680389 DOI: 10.1021/nn501175k] [Citation(s) in RCA: 304] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Recently, two-dimensional layers of transition metal dichalcogenides, such as MoS2, WS2, MoSe2, and WSe2, have attracted much attention for their potential applications in electronic and optoelectronic devices. The selenide analogues of MoS2 and WS2 have smaller band gaps and higher electron mobilities, making them more appropriate for practical devices. However, reports on scalable growth of high quality transition metal diselenide layers and studies of their properties have been limited. Here, we demonstrate the chemical vapor deposition (CVD) growth of uniform MoSe2 monolayers under ambient pressure, resulting in large single crystalline islands. The photoluminescence intensity and peak position indicates a direct band gap of 1.5 eV for the MoSe2 monolayers. A back-gated field effect transistor based on MoSe2 monolayer shows n-type channel behavior with average mobility of 50 cm(2) V(-1) s(-1), a value much higher than the 4-20 cm(2) V(-1) s(-1) reported for vapor phase grown MoS2.
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Affiliation(s)
- Xingli Wang
- Department of Materials Science & NanoEngineering, Rice University , Houston, Texas 77005, United States
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Lu C, Liu WW, Li H, Tay BK. A binder-free CNT network–MoS2 composite as a high performance anode material in lithium ion batteries. Chem Commun (Camb) 2014; 50:3338-40. [DOI: 10.1039/c3cc49647c] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
CNT network and MoS2 are rationally architected into a composite, which demonstrates excellent performances as a binder-free anode material in LIB.
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Affiliation(s)
- Congxiang Lu
- CINTRA CNRS/NTU/THALES
- Nanyang Technological University
- Singapore 637553, Singapore
- Novitas, Nanoelectronics Centre of Excellence
- School of Electrical and Electronic Engineering
| | - Wen-wen Liu
- Novitas, Nanoelectronics Centre of Excellence
- School of Electrical and Electronic Engineering
- Nanyang Technological University
- Singapore 639798, Singapore
| | - Hong Li
- Department of Mechanical Engineering
- Stanford University
- California 94305, USA
| | - Beng Kang Tay
- CINTRA CNRS/NTU/THALES
- Nanyang Technological University
- Singapore 637553, Singapore
- Novitas, Nanoelectronics Centre of Excellence
- School of Electrical and Electronic Engineering
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Labunov V, Prudnikava A, Bushuk S, Filatov S, Shulitski B, Tay BK, Shaman Y, Basaev A. Femtosecond laser modification of an array of vertically aligned carbon nanotubes intercalated with Fe phase nanoparticles. Nanoscale Res Lett 2013; 8:375. [PMID: 24004518 PMCID: PMC3766691 DOI: 10.1186/1556-276x-8-375] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 08/22/2013] [Indexed: 06/02/2023]
Abstract
Femtosecond lasers (FSL) are playing an increasingly important role in materials research, characterization, and modification. Due to an extremely short pulse width, interactions of FSL irradiation with solid surfaces attract special interest, and a number of unusual phenomena resulted in the formation of new materials are expected. Here, we report on a new nanostructure observed after the interaction of FSL irradiation with arrays of vertically aligned carbon nanotubes (CNTs) intercalated with iron phase catalyst nanoparticles. It was revealed that the FSL laser ablation transforms the topmost layer of CNT array into iron phase nanospheres (40 to 680 nm in diameter) located at the tip of the CNT bundles of conical shape. Besides, the smaller nanospheres (10 to 30 nm in diameter) are found to be beaded at the sides of these bundles. Some of the larger nanospheres are encapsulated into carbon shells, which sometime are found to contain CNTs. The mechanism of creation of such nanostructures is proposed.
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Affiliation(s)
- Vladimir Labunov
- Laboratory of Integrated Micro- and Nanosystems, Belarusian State University of Informatics and Radioelectronics, P. Brovka St. 6, Minsk 220013, Republic of Belarus
| | - Alena Prudnikava
- Laboratory of Integrated Micro- and Nanosystems, Belarusian State University of Informatics and Radioelectronics, P. Brovka St. 6, Minsk 220013, Republic of Belarus
| | - Serguei Bushuk
- Laboratory of Optical Diagnostics, B.I. Stepanov Institute of Physics of the National Academy of Sciences of Belarus, Minsk 220072, Republic of Belarus
| | - Serguei Filatov
- Laboratory of Hydrogen Energy, Institute of Heat and Mass Transfer of the National Academy of Sciences of Belarus, Minsk 220072, Belarus
| | - Boris Shulitski
- Laboratory of Integrated Micro- and Nanosystems, Belarusian State University of Informatics and Radioelectronics, P. Brovka St. 6, Minsk 220013, Republic of Belarus
| | - Beng Kang Tay
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Yury Shaman
- Scientific-Manufacturing Complex Technological Centre MIET, K-498, Moscow 103498, Russia
| | - Alexander Basaev
- Scientific-Manufacturing Complex Technological Centre MIET, K-498, Moscow 103498, Russia
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31
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Yap RCC, Li H, Chow WL, Lu CX, Tay BK, Teo EHT. Identifying the mechanisms of p-to-n conversion in unipolar graphene field-effect transistors. Nanotechnology 2013; 24:195202. [PMID: 23579584 DOI: 10.1088/0957-4484/24/19/195202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The mechanisms of p-to-n conversion and vice versa in unipolar graphene field-effect transistors (GFETs) were systematically studied using Raman spectroscopy. Unipolar p-type GFETs are achieved by decorating the graphene surface with a thin layer of titanium (Ti) film, resulting in a Raman D peak. The D peak is observed to recover by annealing the GFET in nitrogen ambient followed by silicon nitride (Si3N4) deposition, suggesting that the Ti adatoms are being partially removed. Furthermore, unipolar n-type GFETs are obtained after the passivation on p-type GFETs. The threshold voltage of the n-type GFET is dependent on the thickness of the Si3N4 layer, which increases as the thickness decreases. A comparison between the Si3N4 and SiO2 passivation layers shows that SiO2 passivation does not convert the GFET into n-type graphene, which identifies the significance of ammonia (NH3) for the formation of the n-type GFETs. This study provides an insight into the mechanism of controlling the conduction behavior of unipolar GFETs.
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Affiliation(s)
- Ray Chin Chong Yap
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore
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32
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Fan Y, Zhang Q, Lu C, Xiao Q, Wang X, Tay BK. High performance carbon nanotube-Si core-shell wires with a rationally structured core for lithium ion battery anodes. Nanoscale 2013; 5:1503-1506. [PMID: 23334522 DOI: 10.1039/c3nr33683b] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Core-shell Si nanowires are very promising anode materials. Here, we synthesize vertically aligned carbon nanotubes (CNTs) with relatively large diameters and large inter-wire spacing as core wires and demonstrate a CNT-Si core-shell wire composite as a lithium ion battery (LIB) anode. Owing to the rationally engineered core structure, the composite shows good capacity retention and rate performance. The excellent performance is superior to most core-shell nanowires previously reported.
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Affiliation(s)
- Yu Fan
- NOVITAS, Nanoelectronics Centre of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798
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33
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Shakerzadeh M, Loh GC, Xu N, Chow WL, Tan CW, Lu C, Yap RCC, Tan D, Tsang SH, Teo EHT, Tay BK. Re-ordering chaotic carbon: origins and application of textured carbon. Adv Mater 2012; 24:4112-4123. [PMID: 22605561 DOI: 10.1002/adma.201104991] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2011] [Revised: 03/02/2012] [Indexed: 05/31/2023]
Abstract
Formation of nanocrystals with preferred orientation within the amorphous carbon matrix has attracted lots of theoretical and experimental attentions recently. Interesting properties of this films, easy fabrication methods and practical problems associated with the growth of other carbon nanomaterials such as carbon nanotubes (CNTs) and graphene gives this new class of carbon nanostructure a potential to be considered as a replacement for some applications such as thermal management at nanoscale and interconnects. In this short review paper, the fabrication techniques and associated formation mechanisms of these nanostructured films have been discussed. Besides, electrical and thermal properties of these nanostructured films have been compared with CNTs and graphene.
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Affiliation(s)
- M Shakerzadeh
- School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798, Singapore
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34
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Zhao ZW, Lei W, Zhang XB, Tay BK, Chen JS. Growth and characterization of bamboo-shaped carbon nanotubes using nanocluster-assembled ZnO:Co thin films as catalyst. J Nanosci Nanotechnol 2012; 12:6583-6587. [PMID: 22962791 DOI: 10.1166/jnn.2012.5427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Bamboo-shaped carbon nanotubes (CNTs) had been successfully fabricated by a plasma enhanced chemical vapor deposition method, in which nanocluster-assembled ZnO:Co thin film was used as catalyst. It was found that bamboo-shaped CNTs were generally grown in a direction perpendicularly to the substrate surface with the tops of CNTs dominated by the droplet-like catalyst covered by the carbon layer. The diameter of CNTs was ranged from 20-50 nm. High resolution of TEM image showed that the typical CNT had a multi-walled structure with an inner core presented. The ordered graphite layers were inclined to an axis of CNT about 18 degrees and the interlayer space of a CNT was about 0.35 nm. Two peaks in Raman spectrum at 1586 cm(-1) and 1372 cm(-1) were identified as G-band and D-band for graphite, respectively. The results showed that catalyst based on ZnO:Co thin films could be used for the growth of CNTs with bamboo-shaped structure.
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Affiliation(s)
- Z W Zhao
- School of Electronic Science and Engineering, Southeast University, Nanjing, 210096, China
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35
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Shakerzadeh M, Teo EHT, Tay BK. Thickness dependency of field emission in amorphous and nanostructured carbon thin films. Nanoscale Res Lett 2012; 7:286. [PMID: 22655860 PMCID: PMC3431989 DOI: 10.1186/1556-276x-7-286] [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] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Accepted: 06/01/2012] [Indexed: 06/01/2023]
Abstract
Thickness dependency of the field emission of amorphous and nanostructured carbon thin films has been studied. It is found that in amorphous and carbon films with nanometer-sized sp2 clusters, the emission does not depend on the film thickness. This further proves that the emission happens from the surface sp2 sites due to large enhancement of electric field on these sites. However, in the case of carbon films with nanocrystals of preferred orientation, the emission strongly depends on the film thickness. sp2-bonded nanocrystals have higher aspect ratio in thicker films which in turn results in higher field enhancement and hence easier electron emission.
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Affiliation(s)
- Maziar Shakerzadeh
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Edwin Hang Tong Teo
- Temasek Laboratories, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Beng Kang Tay
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
- CINTRA, CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore, 637553, Singapore
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Li X, Tay BK, Li J, Tan D, Tan CW, Liang K. Mildly reduced graphene oxide-Ag nanoparticle hybrid films for surface-enhanced Raman scattering. Nanoscale Res Lett 2012; 7:205. [PMID: 22471923 PMCID: PMC3366872 DOI: 10.1186/1556-276x-7-205] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Accepted: 04/03/2012] [Indexed: 05/29/2023]
Abstract
Large-area mildly reduced graphene oxide (MR-GO) monolayer films were self-assembled on SiO2/Si surfaces via an amidation reaction strategy. With the MR-GO as templates, MR-GO-Ag nanoparticle (MR-GO-Ag NP) hybrid films were synthesized by immersing the MR-GO monolayer into a silver salt solution with sodium citrate as a reducing agent under UV illumination. SEM image indicated that Ag NPs with small interparticle gap are uniformly distributed on the MR-GO monolayer. Raman spectra demonstrated that the MR-GO monolayer beneath the Ag NPs can effectively quench the fluorescence signal emitted from the Ag films and dye molecules under laser excitation, resulting in a chemical enhancement (CM). The Ag NPs with narrow gap provided numerous hot spots, which are closely related with electromagnetic mechanism (EM), and were believed to remarkably enhance the Raman signal of the molecules. Due to the co-contribution of the CM and EM effects as well as the coordination mechanism between the MR-GO and Ag NPs, the MR-GO-Ag NP hybrid films showed more excellent Raman signal enhancement performance than that of either Ag films or MR-GO monolayer alone. This will further enrich the application of surface-enhanced Raman scattering in molecule detection.
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Affiliation(s)
- Xiaocheng Li
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
- Temasek Laboratories@NTU, 9th Storey, BorderX Block, Research Techno Plaza, Nanyang Technological University, 50 Nanyang Avenue, Singapore 637553, Singapore
| | - Beng Kang Tay
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
| | - Junshuai Li
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
| | - Dunlin Tan
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
| | - Chong Wei Tan
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
| | - Kun Liang
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
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Yap CC, Brun C, Tan D, Li H, Teo EHT, Baillargeat D, Tay BK. Carbon nanotube bumps for the flip chip packaging system. Nanoscale Res Lett 2012; 7:105. [PMID: 22313721 PMCID: PMC3338392 DOI: 10.1186/1556-276x-7-105] [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] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2011] [Accepted: 02/07/2012] [Indexed: 05/31/2023]
Abstract
Carbon nanotube [CNT] interconnection bump joining methodology has been successfully demonstrated using flip chip test structures with bump pitches smaller than 150 μm. In this study, plasma-enhanced chemical vapor deposition approach is used to grow the CNT bumps onto the Au metallization lines. The CNT bumps on the die substrate are then 'inserted' into the CNT bumps on the carrier substrate to form the electrical connections (interconnection bumps) between each other. The mechanical strength and the concept of reworkable capabilities of the CNT interconnection bumps are investigated. Preliminary electrical characteristics show a linear relationship between current and voltage, suggesting that ohmic contacts are attained.
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Affiliation(s)
- Chin Chong Yap
- CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore, 637553, Singapore
- School of Electrical and Electronics Engineering, Nanyang Technological University, Block S1, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Christophe Brun
- CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore, 637553, Singapore
- XLIM UMR 6172, Université de Limoges/CNRS, 123 Avenue Albert Thomas, Limoges Cedex, 87060, France
| | - Dunlin Tan
- CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore, 637553, Singapore
- School of Electrical and Electronics Engineering, Nanyang Technological University, Block S1, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Hong Li
- School of Electrical and Electronics Engineering, Nanyang Technological University, Block S1, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Edwin Hang Tong Teo
- CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore, 637553, Singapore
- School of Electrical and Electronics Engineering, Nanyang Technological University, Block S1, 50 Nanyang Avenue, Singapore, 639798, Singapore
- Temasek Laboratories@NTU, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 9, Singapore, 637553, Singapore
| | - Dominique Baillargeat
- CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore, 637553, Singapore
| | - Beng Kang Tay
- CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore, 637553, Singapore
- School of Electrical and Electronics Engineering, Nanyang Technological University, Block S1, 50 Nanyang Avenue, Singapore, 639798, Singapore
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Labunov VA, Basaev AS, Shulitski BG, Shaman YP, Komissarov I, Prudnikava AL, Tay BK, Shakerzadeh M. Growth of few-wall carbon nanotubes with narrow diameter distribution over Fe-Mo-MgO catalyst by methane/acetylene catalytic decomposition. Nanoscale Res Lett 2012; 7:102. [PMID: 22300375 PMCID: PMC3347986 DOI: 10.1186/1556-276x-7-102] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Accepted: 02/02/2012] [Indexed: 05/31/2023]
Abstract
Few-wall carbon nanotubes were synthesized by methane/acetylene decomposition over bimetallic Fe-Mo catalyst with MgO (1:8:40) support at the temperature of 900°C. No calcinations and reduction pretreatments were applied to the catalytic powder. The transmission electron microscopy investigation showed that the synthesized carbon nanotubes [CNTs] have high purity and narrow diameter distribution. Raman spectrum showed that the ratio of G to D band line intensities of IG/ID is approximately 10, and the peaks in the low frequency range were attributed to the radial breathing mode corresponding to the nanotubes of small diameters. Thermogravimetric analysis data indicated no amorphous carbon phases. Experiments conducted at higher gas pressures showed the increase of CNT yield up to 83%. Mössbauer spectroscopy, magnetization measurements, X-ray diffraction, high-resolution transmission electron microscopy, and electron diffraction were employed to evaluate the nature of catalyst particles.
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Affiliation(s)
- Vladimir A Labunov
- Belarusian State University of Informatics and Radioelectronics, P. Brovki 6, Minsk 220013, Republic of Belarus
| | | | - Boris G Shulitski
- Belarusian State University of Informatics and Radioelectronics, P. Brovki 6, Minsk 220013, Republic of Belarus
| | - Yuriy P Shaman
- Belarusian State University of Informatics and Radioelectronics, P. Brovki 6, Minsk 220013, Republic of Belarus
- SMC (Technological Centre), Zelenograd, Moscow 124 498, Russia
| | - Ivan Komissarov
- Belarusian State University of Informatics and Radioelectronics, P. Brovki 6, Minsk 220013, Republic of Belarus
| | - Alena L Prudnikava
- Belarusian State University of Informatics and Radioelectronics, P. Brovki 6, Minsk 220013, Republic of Belarus
| | - Beng Kang Tay
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Maziar Shakerzadeh
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore
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39
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Tan CW, Tay BK. Carbon nanowires fabrications via top down approach. J Nanosci Nanotechnol 2012; 12:707-713. [PMID: 22524044 DOI: 10.1166/jnn.2012.5399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Carbon nanowires are fabricated by the Langmuir Blodgett (LB) method via the top down approach on amorphous carbon. Thick a-C films (500 nm to 1 microm) have been successfully deposited after the treatment on silicon. The anisotropic etching of carbon using reactive ion etching (RIE) has been verified giving near vertical sidewalls. The LB method for depositing monolayer requires a hydrophilic surface. Plasma treatment is being performed on the silicon oxide hard mask to reduce the surface energy thereby making the surface from hydrophobic to hydrophilic. PS balls which are being deposited by LB method have one disadvantage which is the low adhesion of the PS ball to the silicon oxide surface. This adhesion is being improved by subjecting the PS ball to annealing which changes the shape and increase the contact area between the PS balls and the silicon oxide surface. As carbon and PS ball is vulnerable to oxygen plasma, a modified recipe of CF4:Ar was being used to etch the silicon oxide hard mask. There is almost little chemical reaction of the CF4 on carbon and PS ball. Carbon nanowires were successfully fabricated using polystyrene (PS) balls of diameter 450 nm. Through a series of steps, carbon nanowire of 500 nm in length and diameter approximately 250 nm can be produced.
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Affiliation(s)
- Chong Wei Tan
- Nanoelectronics Laboratory, School of Electrical and Electronic Engineering, Nanyang Technological University, 1, Block S1, B3, Rm S1-B3a-01, Nanyang Avenue, 639798 Singapore
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Li X, Tay BK. Facile fabrication of Si nanowire arrays for solar cell application. J Nanosci Nanotechnol 2011; 11:10539-10543. [PMID: 22408943 DOI: 10.1166/jnn.2011.3974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Large-area Si nanowire arrays have been fabricated on phosphorus doped Si surface by a facile silver-catalyzed chemical etching process. The solar cell incorporated with Si nanowire arrays shows a power conversion efficiency of 6.69% with an open circuit voltage of 558 mV and a short circuit current density of 25.13 mA/cm2 under AM 1.5 G illumination without using any extra antireflection layer and surface passivation technique. The high power conversion efficiency of Si nanowires based-solar cell is attributed to the low reflectance loss of Si nanowire arrays for incident sunlight. Optimization of electrical contact and phosphorus diffusion process will be critical to improve the performance of Si nanowires-based solar cell in the future.
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Affiliation(s)
- Xiaocheng Li
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798
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Ang CL, Singh G, Goh ASW, Shen L, Tay BK. Densitometry trends in postmenopausal Asian women undergoing bisphosphonate treatment. Singapore Med J 2011; 52:677-680. [PMID: 21947146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
INTRODUCTION Bisphosphonates have been shown to be effective in reducing the risk of fragility fractures in several landmark clinical trials conducted in Western populations. However, limited studies on bone mineral densitometry (BMD) trends have been conducted in Asian women. We conducted a retrospective review of electronic records to determine the actual BMD trends in a local population of postmenopausal women on bisphosphonate treatment. METHODS The electronic records of all women over 50 years of age who had undergone BMD at Singapore General Hospital in 2004 were examined. Patients who were later started on bisphosphonates and continued the treatment for at least two years were selected for the study. Their subsequent BMD results were recorded, and longitudinal analysis was applied to determine the BMD trends as a cohort. RESULTS A total of 254 postmenopausal women were included for analysis. Their mean BMD T-score was -2.70 before treatment, and improved to -2.56 and -2.27 one and two years after treatment, respectively. However, the score deteriorated to -2.50 and -2.62 three and four years after treatment, respectively. The difference between each year's results and those of the baseline was statistically significant. CONCLUSION In our study, the BMD scores in our local population showed improvement in the first two years of bisphosphonate treatment but declined subsequently. Our findings contrasted with those of studies conducted in Western populations. Further prospective studies are suggested so as to elucidate the actual BMD trends and fracture risk reduction in Asian women on bisphosphonate treatment.
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Affiliation(s)
- C L Ang
- Department of Orthopaedic Surgery, Singapore General Hospital, Outram Road, Singapore 169608.
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Han ZJ, Ostrikov KK, Tan CM, Tay BK, Peel SAF. Effect of hydrophilicity of carbon nanotube arrays on the release rate and activity of recombinant human bone morphogenetic protein-2. Nanotechnology 2011; 22:295712. [PMID: 21693800 DOI: 10.1088/0957-4484/22/29/295712] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Novel nanostructures such as vertically aligned carbon nanotube (CNT) arrays have received increasing interest as drug delivery carriers. In the present study, two CNT arrays with extreme surface wettabilities are fabricated and their effects on the release of recombinant human bone morphogenetic protein-2 (rhBMP-2) are investigated. It is found that the superhydrophilic arrays retained a larger amount of rhBMP-2 than the superhydrophobic ones. Further use of a poloxamer diffusion layer delayed the initial burst and resulted in a greater total amount of rhBMP-2 released from both surfaces. In addition, rhBMP-2 bound to the superhydrophilic CNT arrays remained bioactive while they denatured on the superhydrophobic surfaces. These results are related to the combined effects of rhBMP-2 molecules interacting with poloxamer and the surface, which could be essential in the development of advanced carriers with tailored surface functionalities.
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Affiliation(s)
- Zhao Jun Han
- Plasma Nanoscience Centre Australia (PNCA), CSIRO Materials Science and Engineering, Lindfield, New South Wales, Australia.
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Abstract
We report dewetting of thermodynamically stable, thick (approximately 100 nm) polystyrene films by titanium ion implantation. The dynamic dewetting patterns in time evolution are recorded. The dewetting mechanism is determined to be heterogeneous nucleation, where the defects and Ti nanoparticles formed by ion implantation serve as the nuclei. In addition, we observe abundant rims with regular polygonal shapes in dewetting patterns. This is attributed to fingering instability, which results from the balance between the driving force arisen from thermally induced surface tension gradient and the resistive forces from the combination of friction force, Laplace pressure and long-range van der Waals interactions. Finally, a model based on mass conservation is used to qualitatively describe the transition from circular to polygonal shaped rims at a critical diameter for holes.
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Affiliation(s)
- Z J Han
- Nanoelectronics Lab I, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore.
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Lau DWM, McCulloch DG, Taylor MB, Partridge JG, McKenzie DR, Marks NA, Teo EHT, Tay BK. Abrupt stress induced transformation in amorphous carbon films with a highly conductive transition phase. Phys Rev Lett 2008; 100:176101. [PMID: 18518310 DOI: 10.1103/physrevlett.100.176101] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2007] [Indexed: 05/26/2023]
Abstract
We demonstrate that when, and only when, the biaxial stress is increased above a critical value of 6+/-1 GPa during the growth of a carbon film at room temperature, tetrahedral amorphous carbon is formed. This confirms that the stress present during the formation of an amorphous carbon film determines its sp;{3} bonding fraction. In the vicinity of the critical stress, a highly oriented graphitelike material is formed which exhibits low electrical resistance and provides Ohmic contacts to silicon. Atomistic simulations reveal that the structural transitions are thermodynamically driven and not the result of dynamical effects.
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Affiliation(s)
- D W M Lau
- Applied Physics, School of Applied Sciences, RMIT University, GPO Box 2476V Melbourne 3001, Australia
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Zhao ZW, Chen XJ, Tay BK, Chen JS, Han ZJ, Khor KA. A novel amperometric biosensor based on ZnO:Co nanoclusters for biosensing glucose. Biosens Bioelectron 2007; 23:135-9. [PMID: 17478087 DOI: 10.1016/j.bios.2007.03.014] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2006] [Revised: 02/26/2007] [Accepted: 03/19/2007] [Indexed: 10/23/2022]
Abstract
ZnO:Co nanoclusters were synthesized by nanocluster-beam deposition with averaged particle size of 5 nm and porous structure, which were for the first time adopted to construct a novel amperometric glucose biosensor. Glucose oxidase was immobilized into the ZnO:Co nanocluster-assembled thin film through Nafion-assisted cross-linking technique. Due to the high specific active sites and high electrocatalytic activity of the ZnO:Co nanoclusters, the constructed glucose biosensor showed a high sensitivity of 13.3 microA/mA cm2. The low detection limit was estimated to be 20 microM (S/N=3) and the apparent Michaelis-Menten constant was found to be 21 mM, indicating the high affinity of the enzyme on ZnO:Co nanoclusters to glucose. The results show that the ZnO:Co nanocluster-assembled thin films with nanoporous structure and nanocrystallites have potential applications as platforms to immobilize enzyme in biosensors.
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Affiliation(s)
- Z W Zhao
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore.
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Chen X, Yan X, Khor KA, Tay BK. Multilayer assembly of positively charged polyelectrolyte and negatively charged glucose oxidase on a 3D Nafion network for detecting glucose. Biosens Bioelectron 2007; 22:3256-60. [PMID: 17314038 DOI: 10.1016/j.bios.2007.01.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2006] [Revised: 12/04/2006] [Accepted: 01/10/2007] [Indexed: 11/17/2022]
Abstract
In this paper, a novel amperometric glucose biosensor was constructed by alternative self-assembly of positively charged poly(diallydimethylammonium chloride) (PDDA) and negatively charged glucose oxidase (GOx) onto a 3D Nafion network via electrostatic adsorption. The amount of Nafion in the electrode and the number of the (PDDA/GOx)(n) multilayers were optimized to develop a sensitive and selective glucose biosensor. Under optimal conditions, the glucose biosensor with (PDDA/GOx)(5) multilayers exhibited remarkable electrocatalytic activity, capable of detecting glucose with enhanced sensitivity of 9.55 microA/mM cm(2) and a commendably low detection limit of 20 microM (S/N=3). A linear response range of 0.05-7 mM (a linear correlation coefficient of 0.9984, n=20) was achieved. In addition, the glucose biosensor demonstrated superior selectivity towards glucose over some interferents, such as ascorbic acid (AA) and uric acid (UA), at an optimized detection potential of 0.6 V versus Ag/AgCl reference.
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Affiliation(s)
- Xiaojun Chen
- School of Mechanical & Aerospace Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798, Singapore.
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Li C, Yang Y, Sun XW, Lei W, Zhang XB, Wang BP, Wang JX, Tay BK, Ye JD, Lo GQ, Kwong DL. Enhanced field emission from injector-like ZnO nanostructures with minimized screening effect. Nanotechnology 2007; 18:135604. [PMID: 21730382 DOI: 10.1088/0957-4484/18/13/135604] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Injector-like zinc oxide (ZnO) nanostructures have been synthesized on Si substrate by the vapour phase transport method. Samples with different areal densities were obtained by controlling the temperature. The field emission properties of the injector-like ZnO nanostructures showed a clear dependence on the areal density of the nanostructures, which is due to the screening effect. The samples with a needle length of 850 nm and an areal density of 1 × 10(8) cm(-2) showed the lowest field emission turn-on field of 1.85 V µm(-1) at a current density of 10 µA cm(-2), and the current density reaches 1 mA cm(-2) at an applied field of 4.7 V µm(-1).
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Affiliation(s)
- C Li
- School of Electronic Science and Engineering, Southeast University, Nanjing 210096, People's Republic of China. School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, 639798, Singapore
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Abstract
We report that oxidized multiwalled carbon nanotubes (MWCNTs) can be synchronously dispersed and functionalized in TiO2 sol via an in situ sol-gel process. Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and atomic force microscopy (AFM) were used to characterize the functionalized MWCNTs. The results revealed that the hydrolysis and condensation originated from Ti(OC4H9)4 molecules favor the dispersion of MWCNTs in as-prepared TiO2 sol. Based on the strong interaction between the oxidized MWCNTs and TiO2 sol during the in situ sol-gel process, MWCNT (core)-TiOx (shell) tubular composites and TiO2 nanotubes can be obtained through filtrating, washing, and annealing of this kind of TiO2 sol containing functionalized MWCNTs, as revealed by TEM, XPS, Raman spectroscopy, and redispersion experiment. By casting the dilute dispersion of functionalized MWCNTs onto a hydrophilic Si surface, discrete and individual nanotubes can be observed by AFM.
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Affiliation(s)
- Xing-bin Yan
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798.
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Kung AWC, Pasion EG, Sofiyan M, Lau EMC, Tay BK, Lam KS, Wilawan K, Ongphiphadhanakul B, Thiebaud D. A comparison of teriparatide and calcitonin therapy in postmenopausal Asian women with osteoporosis: a 6-month study. Curr Med Res Opin 2006; 22:929-37. [PMID: 16709314 DOI: 10.1185/030079906x104768] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVE The number of hip fractures is expected to double in the next 20 years, with current estimates that Asia will account for 37% of these cases. As bone mineral density (BMD) may be used as a measure of fracture risk, we sought to compare the effects of teriparatide with salmon calcitonin treatment on changes in BMD, biochemical bone markers, and safety in postmenopausal Asian women with osteoporosis. METHODOLOGY A total of 104 patients (n = 47 teriparatide [20 g/day subcutaneously] and n = 57 calcitonin [100 IU/day subcutaneously]) were enrolled in Hong Kong, Singapore, Philippines, Malaysia, and Thailand. Calcium (> or = 500 mg/day) and vitamin D (200-400 IU/day) supplements were taken throughout the 6-month controlled, randomized study. RESULTS Teriparatide was associated with a 5.03 +/- 4.77% increase in lumbar spine BMD (p < 0.0001, mean +/- SD change from baseline), whereas changes in lumbar spine BMD for patients on calcitonin were not statistically significant (mean change of 0.36 +/- 4.12%, p = 0.16). Comparison of the two groups indicated that teriparatide treatment improved lumbar spine BMD statistically significantly more than calcitonin (p < 0.0001). No statistically significant changes were observed for total hip or femoral neck BMD. Serum bone-specific alkaline phosphatase (BSAP) increased by 55.9% (median change from baseline, p < 0.0001) in the teriparatide group, and remained stable with calcitonin (5.0% change, p = 0.24); osteocalcin increased by 156.15% (median change from baseline, p < 0.0001) with teriparatide, and decreased with calcitonin (-15.25%, p = 0.03). Similar rates of adverse events were observed, with nausea and dizziness the most commonly reported for both groups (teriparatide versus calcitonin, 13.0% versus 23.2% p = 0.21, 10.9% versus 21.4% p = 0.19, respectively). There were no clinically relevant changes observed in laboratory parameters. CONCLUSIONS Both treatments were similarly tolerated, however teriparatide was associated with greater increases in lumbar spine BMD and bone formation markers, demonstrating the unique mechanism of action and safety of this treatment for osteoporosis in these Asian women.
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Affiliation(s)
- A W C Kung
- Dept of Medicine, University of Hong Kong, Queen Mary Hospital, China
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Tow BPB, Chang PCC, Mitra AK, Tay BK, Wong MC. Comparing 2-year outcomes of anterior cruciate ligament reconstruction using either patella-tendon or semitendinosus-tendon autografts: a non-randomised prospective study. J Orthop Surg (Hong Kong) 2005; 13:139-46. [PMID: 16131675 DOI: 10.1177/230949900501300206] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
PURPOSE To compare the results of anterior cruciate ligament (ACL) reconstructions using either a patella-tendon autograft or a semitendinosus-tendon autograft. METHODS Based on surgeon experience and preference, 68 patients underwent ACL reconstruction using either a quadruple-strand semitendinosus autograft (n = 34) or a central one-third bone-patella tendon-bone autograft (n = 34). Each patient was assessed preoperatively and postoperatively at 3, 6, and 24 months using the International Knee Documentation Committee (IKDC) knee score, Biodex muscle strength and endurance testing, and the KT1000 instrumented arthrometer test of knee laxity to anterior translation. All assessments at the 2-year follow-up were performed by the same physician and physiotherapist. RESULTS While ACL reconstruction improved knee stability and IKDC knee scores significantly, there was no statistically significant difference between semitendinosus- and patella-tendon autograft reconstructions in terms of long-term knee score or laxity to anterior translation. Semitendinosus graft reconstruction was associated with less donor-site morbidity and hamstring weakness. Meniscectomy was associated with poorer long-term knee scores. CONCLUSION ACL reconstruction is associated with a significantly better IKDC knee score and laxity measurement at 2-year follow-up. However, we were unable to demonstrate a significantly better long-term outcome in knee score or laxity to anterior translation with either a patella-tendon autograft or a semitendinosus-tendon autograft.
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Affiliation(s)
- B P B Tow
- Department of Orthopaedic Surgery, Singapore General Hospital, Singapore
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