• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.146-150
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• 2004

We researched carbon nanotube(CNT) cartridge as a CNT sample for the fabrication of nanotweezer which is composed of a couple of single CNT tip. Our CNT cartridge was made by dielectrophoretic methods, a kind of micromanipulation technique using electric field. Therein we intended to fabricate the CNT cartridge with just conventional function generators and a set of simple electrode. A knife edge and a flat metal electrode were employed as a couple of electrode, and these electrode pair faced each other with the gap. When the gap is filled with CNT suspension, we induced AC electric field into the gap. Then CNTs was attached on the sharp edge in knife edge by dielectrophoresis. This knife edge with attached CNTs is called as the CNT cartridge.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1224-1225
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• 2008

The results of the experiment that was conducted on the electron emission property and the long-term stability of the emission current in various carbon nanotubes (CNTs)-based field emitters with a CNT/catalyst/buffer/W-tip configuration are presented herein. CNT-based field emitters were fabricated by varying the (TiN, Al/Ni/TiN) buffer layer and the (Ni, Co) catalyst material. This study aimed to elucidate how the buffer layers and catalyst materials affect the structural properties of CNTs and the long-term stability of CNT emitters. Raman spectroscopy, field emission SEM, and high-resolution TEM were used to analyze the crystalline structure, surface morphologies, and nanostructures of all the grown CNTs. X-ray photoelectron spectroscopy (XPS) was used to monitor the chemical bonds of all the buffer layers and catalysts. Electron emission measurement and a long-term (up to 40h) stability test were carried out using a compactly designed field emission measurement system.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.150-150
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• 2010

Carbon nanotubes have drawn attention as one of the most promising emitter materials ever known not only due to their nanometer-scale radius of curvature at tip and extremely high aspect ratios but also due to their strong mechanical strength, excellent thermal conductivity, good chemical stability, etc. Some applications of CNTs as emitters, such as X-ray tubes and microwave amplifiers, require high current emission over a small emitter area. The field emission for high current density often damages CNT emitters by Joule heating, field evaporation, or electrostatic interaction. In order to endure the high current density emission, CNT emitters should be optimally fabricated in terms of material properties and morphological aspects: highly crystalline CNT materials, low gas emission during electron emission in vacuum, optimal emitter distribution density, optimal aspect ratio of emitters, uniform emitter height, strong emitter adhesion onto a substrate, etc. We attempted a novel approach to fabricate CNT emitters to meet some of requirements described above, including highly crystalline CNT materials, low gas emission, and strong emitter adhesion. In this study, CNT emitters were fabricated by filtrating an aqueous suspension of highly crystalline thin multiwalled CNTs (Hanwha Nanotech Inc.) through a metal mesh. The metal mesh served as a support and fixture frame of CNT emitters. When 5 ml of the CNT suspension was engaged in filtration through a 400 mesh, the CNT layers were formed to be as thick as the mesh at the mesh openings. The CNT emitter sample of $1{\times}1\;cm^2$ in size was characteristic of the turn-on electrical field of 2.7 V/${\mu}m$ and the current density of 14.5 mA at 5.8 V/${\mu}m$ without noticeable deterioration of emitters. This study seems to provide a novel fabrication route to simply produce small-size CNT emitters for high current emission with reliability.

• 한국정밀공학회지
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• 제23권12호
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• pp.122-127
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• 2006

This paper reports on the development of carbon nanotube tip modified with focused ion beam(FIB). We used an electric field which causes dielectrophoresis, to align and deposit CNTs on a metal-coated canning Probe Microscope (SPM) tip. Using the CNT attached SPM tip, we have obtained an enhanced resolution and wear property compared to that from the bare silicon tip through the scanning of the surface of the bio materials. The carbon nanotube tip was aligned toward the source of the ion beam allowing their orientation to be changed at precise angles. By this technique, metal coated carbon nanotube tips that are several micrometer in length are prepared for SPM.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.986-990
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• 2004

In this paper, we propose a method to estimate the actuating voltage of the nanotweezer made by manual assembly using carbon nanotube. The nanotweezer is composed of two CNT arms that are made by the multiwalled carbon nanotube and tungsten tip. Since the each CNT arm has the macro actuator, the nanotweezer can manipulate a large particle and it is possible to close and open the CNT arm repeatedly. The closing voltage, i.e., actuating voltage is calculated using the capacitance between the carbon nanotubes in CNT arm. We demonstrate the actuation of the nanotweezer using the voltage calculated with the electrostatic force.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.466-466
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• 2011

There have been several methods to fabricate carbon nanotube (CNT) emitters, which include as-grown, spraying, screen-printing, electrophoresis and bonding methods. Unfortunately, these techniques generally suffer from two main problems. One is a weak mechanical adhesion between CNTs and the cathode. The as-grown, spraying and electrophoresis methods show a weak mechanical adhesion between CNTs and the cathodes, which induces CNT emitters pulled out under a high electric field. The other is a severe degradation of the CNT tip due to organic binders used in the fabrication process. The screen-printing method which is widely used to fabricate CNT emitters generally shows a critical degradation of CNT emitters caused by the organic binder. Such kinds of problems induce a short lifetime of the CNT field emitters which may limit their practical applications. Therefore, a robust CNT emitter which has the strong mechanical adhesion and no degradation is still a great challenge. Here, we introduce a simple and effective technique for fabrication of CNT field emitter, namely filtration-taping-transfer method. The CNT emitters fabricated by the filtration-taping-transfer method show the low turn-on electric fields, the high emission current, good uniformity and good stability. The enhanced emission performance of the CNT emitters is mainly attributed to high emission sites on the emitter area, and to good ohmic contact and strong mechanical adhesion between the emitters and cathodes. The CNT emitters using a simple and effective fabrication method can be applied for various field emission applications such as field emission displays, lamps, e-beam sources, and x-ray sources. The detail fabrication process will be covered at the poster.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.682-685
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• 2003

In this paper, we propose the method to measure the Young's modulus of carbon nano tube which was manufactured by chemical vapor deposition. We also made the tungsten tip by electrochemical etching process and the carbon nano tube which was detangled through ultra-sonication with isopropyl alcohol was attached to the tungsten tip. This tip which was composed of tungsten tip and carbon nano tube can be used in Young's modulus measurement by applying DC voltage with counter electrode. The attachment process and measurement of the deflection of carbon nano tube was done under optical microscope.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 춘계학술대회 논문집
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• pp.43-43
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• 2010

we have investigated the field emission characteristics of the CNT/TEOS hybrid thin films fabricated by a spray method. It is found that the CNT/TEOS hybrid emitters show high current density, low turn on field, and long-term emission stability compared to the CNT emitters. These efficient field emission characteristics of the CNT/TEOS hybrid emitters are attributed to the TEOS sol, acting as a protection layer of nanotube emitter by surrounding the nanotube tip as well as a binder material to enhance the adhesion of nanotube emitters to the substrate. Therefore, the CNT/TEOS hybrid emitters could be utilized as an alternative for the efficient and reliable field emitters.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.25.2-25.2
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• 2010

CNT(Carbon Nanotube)는 특이한 구조 및 뛰어난 물성을 갖고 있어, 여러가지 분야에 응용 가능한 신소재로서 연구되어 왔다. 또한 모양 및 구조에 따라 기계, 전기, 화학적인 특성이 달라 다양한 분야에서 활용이 가능하다. 외국에서는 FED tip, TR, 디스플레이 소자, 수소저장체, 고강도 복합체 및 대 표면적 전극 등 CNT의 다양한 특성을 이용한 응용이 연구되고 있는 반면, 국내에서는 이론연구와 합성연구에 편중되어 있다. 본 연구에서는 열 화학 기상법 (Thermal CVD)을 이용하여 MWNT(Multi-wall nano tube)를 성장시켜 촉매두께, 온도, gas변수에 따른 CNT의 양상을 분석하였다. Ni catalyst는 DC magnetron sputter를 이용하여 5~50nm 두께로 증착하였으며, 성장온도는 $800^{\circ}C$에서 $950^{\circ}C$까지 변화시켰다. 기판의 pre-treatment 로 ammonia($NH_3$) gas를 주입한 후, carbon precursor인 methane($CH_4$) gas와 $H_2$ dilute gas를 1:4의 비율로 주입하여 CNT를 성장시켰다. FE-SEM과 TEM, 그리고 XRD를 이용해 성장된 CNT의 형상 및 구조를 분석한 결과, 낮은 온도에서는 100nm이상의 두께를 갖는 수직형상의 MWNT가 성장되었으며, $900^{\circ}C$이상의 높은 온도에서는 20nm이하의 amorphous carbon nano rod가 성장되었다. 각각의 MWNT, carbon nano rod는 온도가 높을수록 직경이 증가하는 추세를 나타냈으며, Ni catalyst가 얇아질수록 수직형상을 갖는 결과가 나타났다. 또한 ammonia gas의 pre-treatment여부에 따라 CNT의 수직 형상이 좌우되는 결과를 확인하였다. 향후 성장된 MWNT의 최적 조건을 도출하여 디스플레이 소자인 FED(Field Emission Display)분야 등에 응용 가능할 것으로 전망된다.

• 한국정밀공학회지
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• 제24권6호
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• pp.113-120
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• 2007

Chemical vapor deposition (CVD) is one of the various synthesis methods that have been employed for carbon nanotube (CNT) growth. In particular, Ren et al reported that large areas of vertically aligned multi-wall carbon nanotubes could be grown using a direct current (dc) PECVD system. The synthesis of CNT requires a metal catalyst layer, etchant gas, and a carbon source. In this work, the substrates consists of Si wafers with Ni-deposited film. Ammonia $NH_3$) and acetylene ($C_2H_2$) were used as the etchant gases and carbon source, respectively. Pretreated conditions had an influence on vertical growth and density of CNTs. And patterned growth of CNTs could be achieved by lithographical defining the Ni catalyst prior to growth. The length of single CNT was increased as niclel dot size increased, but the growth rate was reduced when nickel dot size was more than 200 nm due to the synthesis of several CNTs on single Ni dot. The morphology of the carbon nanotubes by TEM showed that vertical CNTs were multi-wall and tip-type growth mode structure in which a Ni cap was at the end of the CNT.