• Title, Summary, Keyword: carbon nanowires

Search Result 50, Processing Time 0.03 seconds

Precise Resistivity Measurement Independent Of Contact Resistance Influence And Its Applications

  • Kim, Dae-Hyun;Ryu, Hye-Yeon;Ji, Hyun-Jin;Lee, Jae-Woo;Kim, Gyu-Tae
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • /
    • pp.146-147
    • /
    • 2007
  • A universal four-point contact measurement method, has an advantage of non-existence of contact resistance, is demonstrated by the experiments with carbon nanotubes and ZnO nanowire. Ti/Au and Pt are tried to compare the influence of contact resistance between two different metals. These metals are selected to make Ohmic contact and Schottky contact originated from their different work functions. For precise experiments, Ti/Au and Pt are separately evaporated to form double 'four-point contact electrodes' on CNTs or ZnO, and the voltage-current characteristics are measured. This method can be applied to universal resistivity measurement for nanotubes and nanowires.

  • PDF

MWCNTs/V2O5 Nanowire Hetero-junction Actuator Devices (탄소나노튜브/V2O5 나노선 헤테로 구동소자 특성연구)

  • Lee Kang-Ho;Yee Seong-Min;Park So-Jeong;Huh Jung-Hwan;Kim Gyu-Tae;Park Sung-Joon;Ha Jeong-Sook
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.19 no.3
    • /
    • pp.250-254
    • /
    • 2006
  • Hetero-junction sheet actuator composed of carbon nanotubes and $V_{2}O_5$ nanowires were demonstrated in a bimetal configuration. The successive filtration of $V_{2}O_5$ nanowire solution followed by carbon nanotube dispersed water solution in the same way produced a dark-gray colored sheet. A significant actuation was observed in sodium chloride electrolyte solution with a bending direction to the carbon nanotube side at the positive bias voltage against the copper counter-electrode. As the frequency of the applied voltage increased, the amplitudes decreased, indicating a rather slow response of the hetero-film actuator in the electrolyte solution. The hybrid structure enabled an easy fabrication of the film actuator with the enhanced efficiencies.

GaAs-Carbon Nanotubes Nanocomposite: Synthesis and Field-Emission Property (갈륨비소-탄소나노튜브 복합체 제작과 전계방출특성)

  • Lim, Hyun-Chul;Chandrasekar, P.V.;Chang, Dong-Mi;Ahn, Se-Yong;Jung, Hyuk;Kim, Do-Jin
    • Korean Journal of Materials Research
    • /
    • v.20 no.4
    • /
    • pp.199-203
    • /
    • 2010
  • Hybridization of semiconductor materials with carbon nanotubes (CNTs) is a recent field of interest in which new nanodevice fabrication and applications are expected. In this work, nanowire type GaAs structures are synthesized on porous single-wall carbon nanotubes (SWCNTs) as templates using the molecular beam epitaxy (MBE) technique. The field emission properties of the as-synthesized products were investigated to suggest their potential applications as cold electron sources, as well. The SWCNT template was synthesized by the arc-discharge method. SWCNT samples were heat-treated at $400^{\circ}C$ under an $N_2/O_2$ atmosphere to remove amorphous carbon. After heat treatment, GaAs was grown on the SWCNT template. The growth conditions of the GaAs in the MBE system were set by changing the growth temperatures from $400^{\circ}C$ to $600^{\circ}C$. The morphology of the GaAs synthesized on the SWCNTs strongly depends on the substrate temperature. Namely, nano-crystalline beads of GaAs are formed on the CNTs under $500^{\circ}C$, while nanowire structures begin to form on the beads above $600^{\circ}C$. The crystal qualities of GaAs and SWCNT were examined by X-ray diffraction and Raman spectra. The field emission properties of the synthesized GaAs nanowires were also investigated and a low turn-on field of $2.0\;V/{\mu}m$ was achieved. But, the turn-on field was increased in the second and third measurements. It is thought that arsenic atoms were evaporated during the measurement of the field emission.

Structuring of Bulk Silicon Particles for Lithium-Ion Battery Applications

  • Bang, Byoung-Man;Kim, Hyun-Jung;Park, Soo-Jin
    • Journal of Electrochemical Science and Technology
    • /
    • v.2 no.3
    • /
    • pp.157-162
    • /
    • 2011
  • We report a simple route for synthesizing multi-dimensional structured silicon anode materials from commercially available bulk silicon powders via metal-assisted chemical etching process. In the first step, silver catalyst was deposited onto the surface of bulk silicon via a galvanic displacement reaction. Next, the silver-decorated silicon particles were chemically etched in a mixture of hydrofluoric acid and hydrogen peroxide to make multi-dimensional silicon consisting of one-dimensional silicon nanowires and micro-scale silicon cores. As-synthesized silicon particles were coated with a carbon via thermal decomposition of acetylene gas. The carbon-coated multi-dimensional silicon anodes exhibited excellent electrochemical properties, including a high specific capacity (1800 mAh/g), a stable cycling retention (cycling retention of 89% after 20 cycles), and a high rate capability (71% at 3 C rate, compared to 0.1 C rate). This process is a simple and mass-productive (yield of 40-50%), thus opens up an effective route to make a high-performance silicon anode materials for lithiumion batteries.

A study of Physically Implanted Surface Islands by direct Nd:YAG Laser Beam Irradiation

  • Oh, Chang-Heon;Cheon, Suyoung;Lim, Changjin;Lee, Jeongjun;Jeon, Jihyun;Kim, Kyoung-Kook;Chung, Chan-Moon;Cho, Soohaeng
    • Applied Science and Convergence Technology
    • /
    • v.26 no.4
    • /
    • pp.66-69
    • /
    • 2017
  • Physically implanted surface islands of Nano Carbon Tube (NCT) and ${\alpha}-F_2O_3$ particles have been produced on Al-doped ZnO (AZO)/glass surfaces by simple and direct ND:YAG laser beam irradiation. Sheet resistance of the reconstructed surface increased by about 3.6% of over AZO. Minimal surface damage can be repaired by ND:YAG laser beam irradiation in conjunction with proper impurities. Implanted islands of NCT, which are considered to be a good conductive impurity, on AZO increased the sheet resistance by about 1.8%, while implanted islands of ${\alpha}-F_2O_3$, an insulating impurity, on AZO increased sheet resistance by about 129% compared with a laser beam treated AZO. This study provides insight regarding surface implantations of nanowires and micro-circuits, doping effects for semiconductors and optical devices, surface area and impurity effects for catalysis.

Morphology Control of Nanostructured Graphene on Dielectric Nanowires

  • Kim, Byeong-Seong;Lee, Jong-Un;Son, Gi-Seok;Choe, Min-Su;Lee, Dong-Jin;Heo, Geun;Nam, In-Cheol;Hwang, Seong-U;Hwang, Dong-Mok
    • Proceedings of the Korean Vacuum Society Conference
    • /
    • /
    • pp.375-375
    • /
    • 2012
  • Graphene is a sp2-hybridized carbon sheet with an atomic-level thickness and a wide range of graphene applications has been intensely investigated due to its unique electrical, optical, and mechanical properties. In particular, hybrid graphene structures combined with various nanomaterials have been studied in energy- and sensor-based applications due to the high conductivity, large surface area and enhanced reactivity of the nanostructures. Conventional metal-catalytic growth method, however, makes useful applications difficult since a transfer process, used to separate graphene from the metal substrate, should be required. Recently several papers have been published on direct graphene growth on the two dimensional planar substrates, but it is necessary to explore a direct growth of hierarchical nanostructures for the future graphene applications. In this study, uniform graphene layers were successfully synthesized on highly dense dielectric nanowires (NWs) without any external catalysts. We also demonstrated that the graphene morphology on NWs can be controlled by the growth parameters, such as temperature or partial pressure in chemical vapor deposition (CVD) system. This direct growth method can be readily applied to the fabrication of nanoscale graphene electrode with designed structures because a wide range of nanostructured template is available. In addition, we believe that the direct growth growth approach and morphological control of graphene are promising for the advanced graphene applications such as super capacitors or bio-sensors.

  • PDF

Synthesis of Core/Shell Graphene/Semiconductor Nanostructures for Lithium Ion Battery Anodes

  • Sin, Yong-Seung;Jang, Hyeon-Sik;Im, Jae-Yeong;Im, Se-Yun;Lee, Jong-Un;Lee, Jae-Hyeon;Wang, Junyi;Heo, Geun;Kim, Tae-Geun;Hwang, Seong-U;Hwang, Dong-Mok
    • Proceedings of the Korean Vacuum Society Conference
    • /
    • /
    • pp.288-288
    • /
    • 2013
  • Lithium-ion battery (LIB) is one of the most important rechargeable battery and portable energy storage for the electric digital devices. In particular, study about the higher energy capacity and longer cycle life is intensively studied because of applications in mobile electronics and electric vehicles. Generally, the LIB's capacity can be improved by replacing anode materials with high capacitance. The graphite, common anode materials, has a good cyclability but shows limitations of capacity (~374 mAh/g). On the contrary, silicon (Si) and germanium(Ge), which is same group elements, are promising candidate for high-performance LIB electrodes because it has a higher theoretical specific capacity. (Si:4200 mAh/g, Ge:1600 mAh/g) However, it is well known that Si volume change by 400% upon full lithiation (lithium insertion into Si), which result in a mechanical pulverization and poor capacity retention during cycling. Therefore, variety of nanostructure group IV elements, including nanoparticles, nanowires, and hollow nanospheres, can be promising solution about the critical issues associated with the large volume change. However, the fundamental research about correlation between the composition and structure for LIB anode is not studied yet. Herein, we successfully synthesized various structure of nanowire such as Si-Ge, Ge-Carbon and Si-graphene core-shell types and analyzed the properties of LIB. Nanowires (NWs) were grown on stainless steel substrates using Au catalyst via VLS (Vapor Liquid Solid) mechanism. And, core-shell NWs were grown by VS (Vapor-Solid) process on the surface of NWs. In order to characterize it, we used FE-SEM, HR-TEM, and Raman spectroscopy. We measured battery property of various nanostructures for checking the capacity and cyclability by cell-tester.

  • PDF

Template Synthesis of $Ni(OH)_2$ nanowires by Electrochemical Process

  • Zhang, Wentao;Beili, Pang;Lee, Hong-Ro
    • Proceedings of the Korean Institute of Surface Engineering Conference
    • /
    • /
    • pp.68-68
    • /
    • 2008
  • There are several methods for oxide coating on metals, such as aluminum or carbon nanotubes(CNTs). Usually CVD method is introduced for various oxide coating on CNTs. Another method is electrochemical method which use potential-pH diagram for oxide coating on metal or CNTs. In this experiment, electrochemical coating parameter for oxide coating on aluminum template modified by acids and hydrogen peroxide ($H_2O_2$) were examined. SEM micrographs displayed clearly $Ni(OH)_2$ coating on template. For confirmation of electrochemical method application to EDLC electrode material fabrication, EDS spectrum was analyzed.

  • PDF

Ag Nanowires와 혼합물을 이용한 ITO-free 유기태양전지 연구

  • Jang, So-Ra;Yang, Hye-Jin;Go, Geum-Jin;Choe, Cheol-Ho;Choe, Ju-Hwan;Sin, Jin-Guk
    • Proceedings of the Korean Vacuum Society Conference
    • /
    • /
    • pp.467.2-467.2
    • /
    • 2014
  • 유기태양전지는 친환경 에너지 소스로써 저가 대량 생산이 가능하고 특히 유연한 기판에 적용이 가능하여 많은 관심을 받고 있다. 그럼에도 불구하고 기존에 사용되는 indium tin oxide (ITO)의 사용으로 인한 유연성 부족으로 대체되는 투명전극의 개발이 요구되어지고 있다. 이로 인해 carbon nanotubes, graphene, thin metals, metal grids, and conducting polymers 등이 연구되고 있으며, 이중 Silver nanowires (Ag NWs)를 이용한 방식도 많은 관심과 함께 전기광학적 특성에 대한 연구가 진행되고 있다. 하지만 유기전자소자에 사용되기에는 몇 가지 문제점이 발생하는데 이를 해결하기 위한 노력이 다양하게 이루어지고 있다. 특히 다양한 물질의 혼합을 통해 개선하고자 하는 노력이 증가하고 있는데 적층구조의 전도성필름 형성을 통해 ITO-free OPVs에서 Ag nanowire를 transparent conductive electrodes로 활용하였다. Ag NWs층과 PEDOT:PSS layer의 복합화를 통해 저가의 ITO-free OPVs용 transparent anodes가 가능해졌다.

  • PDF

Fabrication of transparent conductive thin films with Ag mesh shape using the polystyrene beads monolayer

  • Jung, Taeyoung;Choi, Eun Chang;Hong, Byungyou
    • Proceedings of the Korean Vacuum Society Conference
    • /
    • /
    • pp.313-313
    • /
    • 2016
  • Transparent conductive oxide (TCO) films have many disadvantages, such as rarity, possible exhaustion, process temperature limitations, and brittleness on a flexible substrate. In particular, as display technology moves toward flexible displays, TCO will become completely unsuitable due to its brittleness. To address theses issue, many researchers have been studying TCO substitutes. In recent efforts, metal nanowires, conducting polymers, carbon nanotube networks, graphene films, hybrid thin films, and metal meshes/grids have been evaluated as candidates to replace TCO electrodes. In this study, we fabricated the TCO film with Ag meshes shape using polystyrene (PS) beads monolayer on the substrate. The PS beads were used as a template to create the mesh pattern. We fabricated the monolayer on the flexible substrate (PES) with the well-aligned PS beads. Electrodes with Ag mesh shape were formed using this patterned monolayer. We could fabricated the Ag mesh electrode with the sheet resistance with $8ohm{\Omega}/{\Box}$.

  • PDF