• Journal of the Microelectronics and Packaging Society
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• v.9 no.4
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• pp.55-60
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• 2002

This paper presents a technique for the preparation of vertically grown CNTs by ICPHFCVD(inductively coupled plasma hot filament chemical vapor deposition) below $580^{\circ}C$. Purification of the CNTs(carbon nanotubes) using RE(radio frequency) plasma in a one step process, based on the different etching property of the Ni-tip, amorphous carbon and carbonaceous materials is also discussed. After purifying the grown materials. CNTs shown the multi walled and hollow typed structure. The typical outer and inner diameters or CNT were 50 nm and 25 nm, respectively. The graphitic wall was composed of 82 layers and the distance between wall and wall was 0.34 nm. From the results of TEM observation, the Ni catalyst at the tip of the carbon nanotubes were effectively removed by using a RF plasma etching, continuously.

• Mass Spectrometry Letters
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• v.6 no.4
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• pp.112-115
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• 2015

In this article, we examine the influences of Ne and He buffer gases under confined Ar⁺ ion cloud in a homemade Paul ion trap in various pressures and confinement times. The trap is of small size (r₀ = 1 cm) operating in a radio frequency (rf) voltage only mode, and has limited accuracy of 13 V. The electron impact and ionization process take place inside the trap and a Faraday cup has been used for the detection. Although the experimental results show that the Ar⁺ ion FWHM with Ne buffer gas is wider than the He buffer gas at the same pressure (1×10^-1 mbar) and confinement time is about 1000 μs, nevertheless, a faster cooling was found with He buffer gas with 500 μs. ultimetly, the obtanied results performed an average cloud tempertures reduced from 1777 K to 448.3 K for Ne (1000 μs) and from 1787.9 K to 469.4 K for He (500 μs)

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.320-320
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• 2011

We describe fabrication of superhydrophobic surface on non-woven fabric (NWF) having nano-hairy structures and a hydrophobic surface coating. Oxygen plasma was irradiated on NWF for nano-texuring and a precursor of HMDSO (Hexamethydisiloxane) was introduced as a surface chemical modification for obtaining superhydrophobicity using 13.56 MHz radio frequency-Plasma Enhanced Chemical Vapor Deposition (rf-PECVD). O2 plasma treatment time was varied from 1 min to 60 min at a bias voltage of 400V, which fabricated pillar-like structures with diameter of 30 nm and height of 150 nm on NWF. Subsequently, hydrophobic coating using hexamethyldisiloxane vapor was deposited with 10 nm thickness on NWF substrate at a bias voltage of 400 V. We evaluate superhydrophobicity of the modified NWF with sessile drop using goniometer and high speed camera, in which aspect ratio of nanohairy structures, contact angle and contact angle hysteresis of the surfaces were measured. With the increase of aspect ratio, the wetting angle increased from $103^{\circ}$ to $163^{\circ}$, and the contact angle hysteresis decreased dramatically below $5^{\circ}$. In addition, we had conducted experiment for nucleation and condensation of water via E-SEM. During increasing vapor pressure inside E-SEM from 3.7 Torr to over 6 Torr which is beyond saturation point at $2^{\circ}C$, we observed condensation of water droplet on the superhydropobic NWF. While the condensation of water on oxygen plasma treated NWF (superhydrophilic) occurred easily and rapidly, superhydrophobic NWF which was fabricated by oxygen and HMDSO was hardly wet even under supersaturation condition. From the result of wetting experiment and water condensation via E-SEM, it is confirmed that superhydrophobic NWF shows the grate water repellent abilities.

• Journal of Powder Materials
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• v.25 no.2
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• pp.120-125
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• 2018

Boron nitride nanotubes (BNNTs) are receiving great attention because of their unusual material properties, such as high thermal conductivity, mechanical strength, and electrical resistance. However, high-throughput and high-efficiency synthesis of BNNTs has been hindered due to the high boiling point of boron (${\sim}4000^{\circ}C$) and weak interaction between boron and nitrogen. Although, hydrogen-catalyzed plasma synthesis has shown potential for scalable synthesis of BNNTs, the direct use of $H_2$ gas as a precursor material is not strongly recommended, as it is extremely flammable. In the present study, BNNTs have been synthesized using radio-frequency inductively coupled thermal plasma (RF-ITP) catalyzed by solid-state ammonium chloride ($NH_4Cl$), a safe catalyst materials for BNNT synthesis. Similar to BNNTs synthesized from h-BN (hexagonal boron nitride) + $H_2$, successful fabrication of BNNTs synthesized from $h-BN+NH_4Cl$ is confirmed by their sheet-like properties, FE-SEM images, and XRD analysis. In addition, improved dispersion properties in aqueous solution are found in BNNTs synthesized from $h-BN+NH_4Cl$.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.6
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• pp.690-696
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• 2010

Abatement of perfluorocompounds (PFCs) used in semiconductor and display industries has received an attention due to the increasingly stricter regulation on their emission. In order to meet this circumstance, we have developed a radio frequency (RF) driven plasma reactor with multiple annular shaped electrodes, characterized by an easy installment between a processing chamber and a vacuum pump. Abatement experiment has been performed with respect to $CF_4$, a representative PFCs widely used in the plasma etching process, by varying the power, $CF_4$ and $O_2$ flow rates, $CF_4$ concentration, and pressure. The influence of these variables on the $CF_4$ abatement was analyzed and discussed in terms of the destruction & removal efficiency (DRE), measured with a Fourier transform infrared (FTIR) spectrometer. The results revealed that DRE was enhanced with the increase in the discharge power and pressure, but dropped with the $CF_4$ flow rate and concentration. The addition of small quantity of $O_2$ lead to the improvement of DRE, which, however, leveled off and then decreased with $O_2$ flow rate.

• Journal of the Korean Vacuum Society
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• v.7 no.4
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• pp.320-327
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• 1998

The chemical aspects of nitridated surface of sapphire(0001) have been studied by X-ray photoelectron spectroscopy. Nitridated layer was formed by remote plasma enhanced-ultrahigh vacuum deposition at a low temperature range. It was confirmed that this nitridated surface was mainly consists of AIN layer. The relative amounts of nitrogen reacted with AL on the sapphire surface and their surface morphology were investigated with X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) as a function of radio-frequency power, reaction temperature, and reaction time. The amounts of atomic nitrogen activated by plasma which was subsequently incorporated into sapphire were increased with RF power. But the amounts of nitrogen reacted with AI in sapphire was initially increased and then remained constant. However, the relative amounts of AIN were nearly constant with irrespective of nitridation temperature and time. Furthermore, a depth porfile of nitridated layer with XPS showed that the nitridated surface consisted of three layers with different stoichiometry.

• Aerospace Engineering and Technology
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• v.12 no.1
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• pp.94-104
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• 2013

In solar system, Mars which has the most similar environment with the Earth has been steadily studied for the purpose of habitable environment for the future manned exploration and settlement. During the daytime, Martian ionosphere can be used for the ground-ground communications between lander and rover through the reflection of the radio wave from ionosphere. In addition, researches about Martian ionosphere provide the link of revolution of water and atmosphere. Martian ionospheric observations were performed by the occultation experiments onboard Mariner, Mars, Viking series during early Martian explorations as well as recent Mars Global Surveyor. Low frequency radar and plasma analyzer are on board Mars Express and Viking-1, 2 lander obtained the only vertical plasma density profile during their entry phase. In this paper, we studied the characteristics of scientific payloads observing Martian ionosphere and then analyzed the usability of ionospheric research according to the communication and climate on Mars.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.04a
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• pp.133-138
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• 2000

MgO thin films were deposited using $Mg(tmhd)_2$ as a precursor dissolved in a solvent by electrostatic spray pyrolysis. When a pure tetra hydro furan was used as a solvent, a large number of particles appeared on the MgO thin film surface due to homogeneous nucleation. However, by adding 1-butyl alcohol or 1-octyl alcohol to THF, homogeneous nucleation was restricted and the number density of the large particles was also drastically reduced. X-ray diffraction analysis showed that the MgO films had a (100) preferred orientation regardless of the type of solvents used. Characterization using Fourier Transformed-Infrared and spectroscopic photometer revealed that the crystallized MgO thin films on the glass substrate had a high optical transmittance (> 85 %) in the visible range. Discharge characteristics of MgO thin films deposited by ESP method on an alternating-current plasma display panel were compared with a MgO thin film prepared by reactive radio-frequency planar magnetron sputtering.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.7
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• pp.618-623
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• 2006

Hydrogenated Diamond-like carbon (DLC) films were prepared by the radio frequency plasma enhanced chemical vapor deposition (RF PECVD) method on silicon substrates using methane $(CH_4)$ and hydrogen $(H_2)$ gas. The wear track on the DLC films was examined after the ball-on disk (BOD) measurement with a Raman mapping method. The BOD measurement of the DLC films was performed for 1 to 3 hours with a 1-hour step time. The sliding traces on the hydrogenated DLC film after the BOD measurement were also observed using an optical microscope. The surface roughness and cross-sectional images of the wear track were obtained using an atomic force microscope (AFM). The novel Raman mapping method effectively shows the graphitization of DLC films of $300{\mu}m\times300{\mu}m$ area according to the sliding time by G-peak positions (intensities) and $I_D/I_G$ ratios.

• Tribology and Lubricants
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• v.22 no.3
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• pp.127-130
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• 2006

DLC (Diamond Like Carbon) films show very desirable surface interactions with high hardness, low friction coefficient, and good wear-resistance properties. The friction behavior of hydrogenated DLC film is dependent on tribological environment, especially surrounding temperature. In this work, the tribological behaviors of DLC (Diamond-like carbon) films, prepared by the radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) method, were studied in elevated temperatures. The ball-on-disk tests with DLC films on steel specimens were conducted at a sliding speed of 60 rpm, a load of 10N, and surrounding various temperatures of $25^{\circ}C,\;40^{\circ}C,\;55^{\circ}C\;and\;75^{\circ}C$. The results show considerable dependency of DLC tribological parameters on temperature. The friction coefficient decreased as the surrounding temperature increased. After tests the wear tracks of hydrogenated DLC film were analyzed by optical microscope, scanning electron spectroscopy (SEM) and Raman spectroscopy. The surface roughness and 3-D images of wear track were also obtained by an atomic force microscope (AFM).