Publications (9)24.05 Total impact

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    ABSTRACT: To investigate emission properties of the photosensitive carbon nanotube emitters using ethanol as developer, a photosensitive carbon nanotube paste was formulated. for patterning of carbon nanotube paste, backside exposure and development process were carried out after screen printing and drying process. Ethanol is not only formed pattern but also removed organic vehicles in the photosensitive carbon nanotube film. The emission properties of patterned carbon nanotube film with and without firing were evaluated.
    No preview · Article · May 2007 · SID Symposium Digest of Technical Papers
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    ABSTRACT: We have studied, for the first time, the field emission from the film, prepared by a spray method, of the finely dispersed black core material, including multi-walled carbon nanotubes (MWNTs), fabricated by arc discharge. We dispersed the black core material by using an ultrasonic processor and found that the dispersed ones were much finer than those observed when treated with a ball mill and normal ultra-sonic bath. By SEM, HRTEM and Raman analyses, the MWNTs were almost not deformed and damaged during ultra-sonication. The field emission current density measured from the film of the dispersed black core material was about 15 mA/cm2 at an applied field of 8 V/μm, which was about 23 times higher than that found by a ball mill. A current density of 1 mA/cm2, which is required basically for flat panel display, has been obtained at 5.3 V/μm. The lifetime test of the dispersed black core material showed that the current density was almost unchanged while the field was applied. Therefore, it is concluded that a black core material fabricated by arc discharge could be used to flat panel displays as field emitters by dispersing with an ultrasonic processor, without further treatment like extraction or purification.
    Preview · Article · Dec 2005 · Carbon
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    ABSTRACT: We have installed two nanomanipulators, which can travel about 20mm with a minimum increment of 1 nm, for manipulation of nanostructured materials inside field-emission scanning electron microscope (FE-SEM). Both manipulators render motions in x, y, and z directions, providing various manipulation freedoms such as moving, bending, cutting, and biasing. In addition, we have conducted in situ characterization of the electrical breakdown of multi-walled carbon nanotubes (MWCNTs). Our results demonstrate the possibility that MWCNTs can be used as a gas sensor.
    Full-text · Article · Feb 2005 · Micron
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    ABSTRACT: We have developed a new gas-phase synthesis technique to produce carbon nanotubes (CNTs) with a continuous process and at high temperature, by using a thermal plasma jet. A thermal plasma jet was generated by applying a direct current of 100–300 A, using Ar as the plasma gas with a flow rate of ∼6 ksccm. The temperature of the thermal plasma jet was very high (∼104 K) and the velocity was very fast (∼100 m/s). Fe(CO)5 and CO were used as a catalyst precursor and carbon source, respectively. The yield of CNTs was dramatically increased by attaching a helical extension reactor at the end of the plasma nozzle. High purity (∼80%) CNTs were produced with a continuous process by using a thermal plasma jet with helical extension reactor equipment. The number of CNT walls produced was critically affected by the hydrogen gas injected as an auxiliary plasma gas. Without hydrogen gas, single-walled carbon nanotubes whose diameter was about 1 nm were mostly produced while with hydrogen gas double-walled carbon nanotubes (about 4 nm in diameter) were predominantly produced, with small amount of 3- and 4-walled carbon nanotubes.
    Full-text · Article · Dec 2004 · Carbon
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    ABSTRACT: The developing of a thermal plasma jet (TPJ) system to produce controlled carbon nanotube (CNT) in a continuous process was investigated. High-purity single-, double- and multi-walled carbon nanotubes were synthesized selectively over catalysts by varying the inlet location of carbon source, with or without H2 gas. Typical HRTEM images of the CNT produced and Fe particles collected were developed. It was also found that the size of the particles increased with the time because of the number of particles.
    No preview · Article · Dec 2004 · Carbon
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    ABSTRACT: We analyzed the microstructure of double-walled carbon nanotubes (DWNTs) synthesized by chemical vapor deposition (CVD) method and investigated field emission of properties DWNTs screen printed. We fabricated 1-inch triode type CNTs flat lamp.
    No preview · Conference Paper · Aug 2004
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    ABSTRACT: In this work, we fabricate 1-in carbon nano tubes (CNTs) flat lamp of diode and triode structure. The CNTs have been directly grown on soda-lime glass substrate by thermal growth method. To know the optimized flat lamp structure, we have simulated the electric field distribution in these structures by the Maxwell simulator. The metal-mesh grid is inserted between an anode and cathode plate for dispersion of emitted electrons and decrease of turn-on voltage, and we investigate the trajectory of emitted electrons in the triode structure. Also, we suggest the direct joint packaging method, which needs no exhausting hole and tube. The CNTs flat lamps are successfully packaged and fully emitted with high brightness. The emission and brightness properties of CNTs are investigated for various conditions.
    No preview · Article · May 2004 · Vacuum
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    ABSTRACT: We have investigated effects of post-treatment of carbon nanotubes(CNTs) films on field emission characteristics. CNTs films were prepared with Ar plasma treatment of different exposure times. With the Ar plasma treatment, electron emission at low threshold field was observed and higher emission current at 2.9 V/μm was generated, compared to the untreated films. Also the field emission site density of CNTs films was improved by Ar plasma treatment. We show that electrons can be emitted from not only CNT tip but also irradiation-induced defects on CNTs walls.
    No preview · Article · Jan 2004 · SID Symposium Digest of Technical Papers
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    ABSTRACT: We have used two piezoelectric nanomanipulators to manage the multiwalled carbon nanotubes (MWCNTs) within the field emission-scanning electron microscope (FE-SEM). For an easy access of a tungsten tip to MWCNTs, we prepared the tungsten tip in sharp and long tip geometry using different electrochemical etching parameters. In addition, the sample stage was tilted by 45° from the normal direction of the surface to allow a better incident angle to the approaching tungsten tip. For manipulations, a nanotube or the bundles were attached at the tungsten tip using an electron beam-induced deposition (EBID). Using two manipulators, we have then fabricated a CNT-based transistor, a cross-junction of MWCNTs, and a CNT-attached atomic force microscopy tip. After these fabrications, the field emission properties of the MWCNT and junction properties of the MWCNT and the tungsten tip have been investigated. We found that the EBID approach was very useful to weld the nanostructured materials on the tungsten tip by simply irradiating the electron beam, although this sometimes increased the contact resistance by depositing hydrocarbon materials. © 2003 American Institute of Physics.
    Full-text · Article · Aug 2003 · Review of Scientific Instruments