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Yang Q, Gong Z, Xiao S, Zhang D, Ma L. Establishing Ohmic Contact of a Radial Compressed CNT Bundle with High Work Function Metal. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:10460-10467. [PMID: 38441484 DOI: 10.1021/acs.langmuir.3c03395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Establishing low-resistance ohmic contact is critical for developing electronic devices based on traditional silicon and new low-dimensional materials. Due to unprecedented electronic and mechanical properties, the one-dimensional carbon nanotubes (CNTs) have been used as source/drain, gate, or tunnel to fabricate transistors. However, the mechanism causing low-resistance ohmic contact is not clear yet. Here, the hybrid atomic force microscopy-scanning electron microscopy (AFM-SEM) instrument was developed to establish lower-resistance ohmic contact between a radial compressed deformed multiwalled CNT bundle and high work function metal (platinum and gold). The radial compression structure under strong van der Waals attraction was in situ characterized through the SEM image to obtain the diameter and width and through AFM to get height and to perform nanoindentation, indicating that Pt has the smaller radial compression deformation. Molecular dynamics simulations exhibit that compared to Pt, a wider ribbon-like graphene layer formed when the radial compressed CNTs contacted with Au. The bond forming and electron orbital overlapping between C atoms of deformed CNTs and the high work function metal atom is beneficial for good electrical contact.
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Affiliation(s)
- Quan Yang
- College of Integrated Circuits, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 310027, China
| | - Zhihao Gong
- Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 311200, China
| | - Shungen Xiao
- School of Information Engineering, Ningde Normal University, Ningde 352100, China
| | - Dongxing Zhang
- Shenzhen Institute for Advanced Study, University of Electronics Science and Technology of China, Shenzhen 518110, China
| | - Li Ma
- School of Mechatronic Engineering and Automation, Shanghai University, Shanghai 200444, China
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Yang Q, Ma L, Xiao S, Zhang D, Djoulde A, Ye M, Lin Y, Geng S, Li X, Chen T, Sun L. Electrical Conductivity of Multiwall Carbon Nanotube Bundles Contacting with Metal Electrodes by Nano Manipulators inside SEM. NANOMATERIALS 2021; 11:nano11051290. [PMID: 34068361 PMCID: PMC8153315 DOI: 10.3390/nano11051290] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 05/07/2021] [Accepted: 05/10/2021] [Indexed: 11/16/2022]
Abstract
Determining the metallicity and semiconductivity of a multi-walled carbon nanotube (MWCNT) bundle plays a particularly vital role in its interconnection with the metal electrode of an integrated circuit. In this paper, an effective method is proposed to determine the electrical transport properties of an MWCNT bundle using a current-voltage characteristic curve during its electrical breakdown. We established the reliable electrical nanoscale contact between the MWCNT bundle and metal electrode using a robotic manipulation system under scanning electron microscope (SEM) vacuum conditions. The experimental results show that the current-voltage curve appears as saw-tooth-like current changes including up and down steps, which signify the conductance and breakdown of carbon shells in the MWCNT bundle, respectively. Additionally, the power law nonlinear behavior of the current-voltage curve indicates that the MWCNT bundle is semiconducting. The molecular dynamics simulation explains that the electron transport between the inner carbon shells, between the outermost carbon shells and gold metal electrode and between the outermost carbons shells of two adjacent individual three-walled carbon nanotubes (TWCNTs) is through their radial deformation. Density functional theory (DFT) calculations elucidate the electron transport mechanism between the gold surface and double-wall carbon nanotube (DWCNT) and between the inner and outermost carbon shells of DWCNT using the charge density difference, electrostatic potential and partial density of states.
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Affiliation(s)
- Quan Yang
- School of Mechatronic Engineering and Automation, Shanghai University, Shanghai 200444, China; (Q.Y.); (A.D.); (M.Y.); (Y.L.); (S.G.)
| | - Li Ma
- School of Mechatronic Engineering and Automation, Shanghai University, Shanghai 200444, China; (Q.Y.); (A.D.); (M.Y.); (Y.L.); (S.G.)
- Correspondence: (L.M.); (S.X.); (X.L.); (T.C.)
| | - Shungen Xiao
- School of Information, Mechanical and Electrical Engineering, Ningde Normal University, Ningde 352100, China
- Correspondence: (L.M.); (S.X.); (X.L.); (T.C.)
| | - Dongxing Zhang
- Shenzhen Institute for Advanced Study, University of Electronics Science and Technology of China, Shenzhen 518110, China;
| | - Aristide Djoulde
- School of Mechatronic Engineering and Automation, Shanghai University, Shanghai 200444, China; (Q.Y.); (A.D.); (M.Y.); (Y.L.); (S.G.)
| | - Maosheng Ye
- School of Mechatronic Engineering and Automation, Shanghai University, Shanghai 200444, China; (Q.Y.); (A.D.); (M.Y.); (Y.L.); (S.G.)
| | - Yini Lin
- School of Mechatronic Engineering and Automation, Shanghai University, Shanghai 200444, China; (Q.Y.); (A.D.); (M.Y.); (Y.L.); (S.G.)
| | - Songchao Geng
- School of Mechatronic Engineering and Automation, Shanghai University, Shanghai 200444, China; (Q.Y.); (A.D.); (M.Y.); (Y.L.); (S.G.)
| | - Xuan Li
- Robotics and Microsystems Centre, Soochow University, Suzhou 215021, China;
- Correspondence: (L.M.); (S.X.); (X.L.); (T.C.)
| | - Tao Chen
- Robotics and Microsystems Centre, Soochow University, Suzhou 215021, China;
- Correspondence: (L.M.); (S.X.); (X.L.); (T.C.)
| | - Lining Sun
- Robotics and Microsystems Centre, Soochow University, Suzhou 215021, China;
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Zhu W, Zhang Y, Xu N, Tan Y, Zhan R, Shen Y, Xu Z, Bai X, Chen J, She J, Deng S. Epitaxial growth of multiwall carbon nanotube from stainless steel substrate and effect on electrical conduction and field emission. NANOTECHNOLOGY 2017; 28:305704. [PMID: 28681729 DOI: 10.1088/1361-6528/aa780c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The epitaxial growth of carbon nanotubes (CNTs) is an important subject of research. Recent attention has been paid to finding new strategies for the controlled growth of single-wall CNTs with a defined chirality. In addition, many potential applications require multiwall CNTs (MWCNTs) to grow vertically from the substrate and the interface property is crucial. Here, we report for the first time that MWCNTs can grow directly from the surface of a substrate by epitaxy, based on the experimental study of individual multiwall carbon nanotubes on a large-area stainless steel substrate, which is a very useful system for electrical and mechanical applications. In particular, evidence is given of the lattice matching between the MWCNT and the lattice of a hexagonal Cr2O3: (Fe, Mn) film formed on the surface of the substrate. Furthermore, a method is developed to increase the density of the MWCNTs; a mechanism of simultaneous top and bottom growth is proposed. The resultant significantly improved electrical transport and field emission properties are also presented, showing the Ohmic contact for electrical conduction and high performance in resisting the catastrophic cold-cathode vacuum breakdown of the CNTs.
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Affiliation(s)
- Weiwei Zhu
- State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, People's Republic of China. School of Materials Science and Engineering, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China
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Kahng YH, Lee S, Choe M, Jo G, Park W, Yoon J, Hong WK, Cho CH, Lee BH, Lee T. A study of graphene films synthesized on nickel substrates: existence and origin of small-base-area peaks. NANOTECHNOLOGY 2011; 22:045706. [PMID: 21169664 DOI: 10.1088/0957-4484/22/4/045706] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Large-area graphene films, synthesized by the chemical vapor deposition (CVD) method, have the potential to be used as electrodes. However, the electrical properties of CVD-synthesized graphene films fall short of the best results obtained for graphene films prepared by other methods. Therefore, it is important to understand the reason why these electrical properties are inferior to improve the applicability of CVD-grown graphene films. Here, we show that CVD-grown graphene films on nickel substrates contain many small-base-area (SBA) peaks that scatter conducting electrons, thereby decreasing the Hall mobility of charges in the films. These SBA peaks were induced by small peaks on the nickel surface and are likely composed of amorphous carbon. The formation of these SBA peaks on graphene films was successfully suppressed by controlling the surface morphology of the nickel substrate. These findings may be useful for the development of a CVD synthesis method that is capable of producing better quality graphene films with large areas.
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Affiliation(s)
- Yung Ho Kahng
- Department of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea.
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The effect of amorphous carbon layer on the field emission characteristics of carbon nanotube film. Ultramicroscopy 2010; 111:426-30. [PMID: 21159440 DOI: 10.1016/j.ultramic.2010.11.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Revised: 11/04/2010] [Accepted: 11/10/2010] [Indexed: 11/23/2022]
Abstract
Carbon nanotube (CNT) has excellent field emission characteristics and could play as a good cold cathode in the application of vacuum electronic devices. However, the practical application faces a big obstacle regarding current fluctuation and deterioration of the CNT cathode. In this research, the formation of amorphous carbon (ac) layer between the CNT film and the substrate, and the effect of the existence of this layer on field emission stability of the CNT film are studied. The formation of the ac layer could be controlled by adjustment of growth temperature and hydrocarbon flow rate. The field emission character and current stability of the CNT film without ac layer are better than those of the CNT film with ac layer. The results attribute to the ac layer a thermal disequilibrium state under high current level. Moreover, adhesion capacity of the CNT film without ac layer is also better than that with the ac layer. It is concluded that the ac layer between the CNT film and substrate is a key factor in the stability of field emission characteristics and should be eliminated before applications.
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Castellanos-Gomez A, Agraït N, Rubio-Bollinger G. Carbon fibre tips for scanning probe microscopy based on quartz tuning fork force sensors. NANOTECHNOLOGY 2010; 21:145702. [PMID: 20220220 DOI: 10.1088/0957-4484/21/14/145702] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We report the fabrication and the characterization of carbon fibre tips for use in combined scanning tunnelling and force microscopy based on piezoelectric quartz tuning fork force sensors. We find that the use of carbon fibre tips results in a minimum impact on the dynamics of quartz tuning fork force sensors, yielding a high quality factor and, consequently, a high force gradient sensitivity. This high force sensitivity, in combination with high electrical conductivity and oxidation resistance of carbon fibre tips, make them very convenient for combined and simultaneous scanning tunnelling microscopy and atomic force microscopy measurements. Interestingly, these tips are quite robust against occasionally occurring tip crashes. An electrochemical fabrication procedure to etch the tips is presented that produces a sub-100-nm apex radius in a reproducible way which can yield high resolution images.
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Affiliation(s)
- A Castellanos-Gomez
- Departamento de Física de la Materia Condensada (C-III), Universidad Autónoma de Madrid, Campus de Cantoblanco, Madrid, Spain
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Rykaczewski K, Hildreth OJ, Kulkarni D, Henry MR, Kim SK, Wong CP, Tsukruk VV, Fedorov AG. Maskless and resist-free rapid prototyping of three-dimensional structures through electron beam induced deposition (EBID) of carbon in combination with metal-assisted chemical etching (MaCE) of silicon. ACS APPLIED MATERIALS & INTERFACES 2010; 2:969-973. [PMID: 20356053 DOI: 10.1021/am1000773] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
In this work, we introduce a maskless, resist-free rapid prototyping method to fabricate three-dimensional structures using electron beam induced deposition (EBID) of amorphous carbon (aC) from a residual hydrocarbon precursor in combination with metal-assisted chemical etching (MaCE) of silicon. We demonstrate that EBID-made patterned aC coating, with thickness of even a few nanometers, acts as a negative "mask" for the etching process and is sufficient for localized termination of the MaCE of silicon. Optimal aC deposition settings and gold film thickness for fabrication of high-aspect-ratio nanoscale 3D silicon structures are determined. The speed necessary for optimal aC feature deposition is found to be comparable to the writing speed of standard Electron Beam Lithography and the MaCE etching rate is found to be comparable to standard deep reactive ion etching (DRIE) rate.
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Rykaczewski K, Henry MR, Kim SK, Fedorov AG, Kulkarni D, Singamaneni S, Tsukruk VV. The effect of the geometry and material properties of a carbon joint produced by electron beam induced deposition on the electrical resistance of a multiwalled carbon nanotube-to-metal contact interface. NANOTECHNOLOGY 2010; 21:035202. [PMID: 19966395 DOI: 10.1088/0957-4484/21/3/035202] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Multiwall carbon nanotubes (MWNTs) are promising candidates for yielding next generation electrical and electronic devices such as interconnects and tips for conductive force microscopy. One of the main challenges in MWNT implementation in such devices is the high contact resistance of the MWNT-metal electrode interface. Electron beam induced deposition (EBID) of an amorphous carbon interface has previously been demonstrated to simultaneously lower the electrical contact resistance and improve the mechanical characteristics of the MWNT-electrode connection. In this work, we investigate the influence of process parameters, such as the electron beam energy, current, geometry, and deposition time, on the EBID-made carbon joint geometry and electrical contact resistance. The influence of the composition of the deposited material on its resistivity is also investigated. The relative importance of each component of the contact resistance and the limiting factor of the overall electrical resistance of a MWNT-based interconnect is determined through a combination of a model analysis and comprehensive experiments.
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Affiliation(s)
- Konrad Rykaczewski
- Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
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Kahng YH, Choi J, Jeong K, Park BC, Kim DH, Lyou J, Lee JJ, Lee H, Lee T, Ahn SJ. Fabrication of ball-shaped atomic force microscope tips by ion-beam-induced deposition of platinum on multiwall carbon nanotubes. Ultramicroscopy 2009; 110:82-8. [PMID: 19853998 DOI: 10.1016/j.ultramic.2009.09.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2009] [Revised: 09/14/2009] [Accepted: 09/22/2009] [Indexed: 10/20/2022]
Abstract
Ball-shaped atomic force microscope (AFM) tips (ball tips) are useful in AFM metrology, particularly in critical dimension AFM metrology and in micro-tribology. However, a systematic fabrication method for nano-scale ball tips has not been reported. We report that nano-scale ball tips can be fabricated by ion-beam-induced deposition (IBID) of Pt at the free end of multiwall carbon nanotubes that are attached to AFM tips. Scanning electron microscopy and transmission electron microscopy analyses were done on the Pt ball tips produced by IBID in this manner, using ranges of Ga ion beam conditions. The Pt ball tips produced consisted of aggregated Pt nano-particles and were found to be strong enough for AFM imaging.
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Affiliation(s)
- Yung Ho Kahng
- Korea Research Institute of Standards and Science, Daejeon 305-340, Republic of Korea
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