• Journal of the Korean Vacuum Society
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• v.4 no.S2
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• pp.95-99
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• 1995

keV ion beam irradiatin for surface modification and thin film growth have been discussed. keV ion beam irradiation in reactive gas environment has been developed for improving wettability of polymer, and for enhancing adhesion to metal film, and adventages of the method have been reviewed. An epitaxial Cu film on Si(100) substrate has been grown by ionized cluster beam and changes of crystallinity and surface roughness have been discussed. Stoichiometric $SnO_2$ films on Si(100) and glass have been grown by a hybrid ion beam Deposition(2 metal ion sources+1 gas ion source), and nonstoichiometric $SnO_2$ films are controlled by various deposition conditions in the HIB. Surface modification for polymer by kev ion irradiation have been developed. Wetting angle of water to PC has been changed from 68 degree to 49 degree with $Ar^+$ irradiation and to 8 degree with $Ar^+$ irradiation and the oxygen environment. Change of surface phenomena in a keV ion beam and characteristics of the grown films are suggested.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.232-235
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• 2002

An 150 kV gas cluster ion accelerator was fabricated and assessed. The change of surface morphology and surface roughness were examined by an atom force microscope (AFM) after irradiation of $CO_2$ gas clusters on Si (100) surfaces at the acceleration voltages of 50 kV. The density of hillocks induced by cluster ion impact was gradually increased with the dosage up to 5$\times$10$^{11}$ ions/$\textrm{cm}^2$. At the boundary of the ion dosage of 10$^{12}$ ions/$\textrm{cm}^2$, the density of the induced hillocks was decreased and RMS (root mean square) surface roughness was not deteriorated further. At the dosage of 5x10$^{13}$ ions/$\textrm{cm}^2$, the induced hillocks completely disappeared and the surface became very flat. In addition, the irradiated region was sputtered. $CO_2$ cluster ions are irradiated at the acceleration voltage of 25 kV to remove hillocks on indium tin oxide (ITO) surface and thus to attain highly smooth surfaces. $CO_2$ monomer ions are also bombarded on the ITO surface at the same acceleration voltage to compare sputtering phenomena. From the AFM results, the irradiation of monomer ions make the hillocks sharper and the surfaces rougher On the other hand, the irradiation of $CO_2$ cluster ions reduces the hight of hillocks and planarize the ITO surfaces. From the experiment of isolated cluster ion impact on the Si surfaces, the induced hillocks m high had the surfaces embossed at the lower ion dosages. The surface roughness was slightly increased with the hillock density and the ion dosage. At higher than a critical ion dosage, the induced hillocks were sputtered and the sputtered particles migrated in order to fill valleys among the hillocks. After prolonged irradiation of cluster ions, the irradiated region was very flat and etched.

• Proceedings of the Korean Vacuum Society Conference
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• 1993.07a
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• pp.39-39
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• 1993

A finite element analysis and Monte Carlo method have been applied to calculate the ppressure pprofiles around the ppohang Light Source (ppLS) electron storage ring with the aim of ppredicting the pperformance of the vacuum system designed for the ppLS vacuum system. After ppropperly choosing the design pparameters, the ppressure distribution are calculated as a function of the integrated stored beam current [AmppHrs]. The effect of changes of the vacuum pparameters, such as installed ppumpping sppeeds and synchrotron radiation induced gas desorpption rates on the ppressure pprofile, is also studied. The results indicate that the use of lumpped non-evapporable getter ppumpps together with spputter ion ppumpps for ppumpping the ppLS down to the required ppressure is ppossible in the ppresence of synchrotron induced gas loads, after resonable beam cleaning time.

• Advances in materials Research
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• v.4 no.2
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• pp.63-76
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• 2015

The energy crisis involving depletion of fossil fuel resource is not the sole driving force for developing renewable energy technologies. Another driving force is the ever increasing concerns on the air quality of our planet, associated with the continuous and dramatic increase of the concentration of greenhouse gas (mainly carbon dioxide) emissions. The internal combustion engine is a major source of distributed $CO_2$ emissions caused by combustion of gasoline derived largely from fossil fuel. Another major source of $CO_2$ is the combustion of fossil fuels to produce electricity. New technologies for generating electricity from sources that do not emit $CO_2$, such as water, solar, wind, and nuclear, together with the advent of plug-in hybrid electric vehicles (PHEV) and even all-electric vehicles (EVs), offer the potential of alleviating our present problem. Therefore, the relevant technologies in $LiFePO_4$ as cathode material for Li-ion batteries suitable to the friendly environment are reviewed aim to provide the vital information about the growing field for energies to minimize the potential environmental risks.

• Journal of the Korean institute of surface engineering
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• v.31 no.2
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• pp.73-80
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• 1998

The aim of this study is to develop sintered stainless steels (SSS) with good mechanical strength, wear resistance, and corrosion resistance by nitrogen ion implantation on the Culated SSS surface. Stainless steel compacts containg Cu (2-10 wt%) were prepared by electroless Cu-pating method which results in the increased3 homogenization in alloying powder. Nitrogen ion implantation was carried out by using N2 gas as the ion source. Nitrogen ions were embedded by an acceleratol of 130keV with doese $3.0\times10^{17}\;ions/\textrm{cm}^2$ on the SSS at $25^{\circ}C$ in$2\times10^{-6}$ torr vacuum. The nitrogen ion implanted SSS obtained from anodic ploarization curves revealed higher corrosion potential than that of nitrogen ion unimplante one. And nitrogen ion implanted 316LSSS had good resistance to pitting corrosion due to the synergistic effect of Mo and N, and the inhibition of $NH_4\;^+$<\TEX>, against $CI^-$<\TEX>.

• Journal of the Korean Vacuum Society
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• v.17 no.4
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• pp.262-269
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• 2008

The residual gas analyzer (RGA) is employed for the process control of a vacuum system by measuring residual gases in it. This review paper introduces operating principles of the RGA and problems that can be encountered during use, together with their possible solutions.

• Proceedings of the IEEK Conference
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• 2000.06b
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• pp.282-285
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• 2000

Four helical resonators are distributed in a 2 ${\times}$ 2 array by modifying upper part of the conventional reactive ion etching(RIE) type LCD etcher in order to prepare a large area plasma source. Since the resonance condition of the RF signal to the helical antenna, one RF power supply is used for delivering the power efficiently to all four helical resonators without an impedance matching network Previous work of 2 ${\times}$ 2array inductively coupled plasma(ICP)requires one matching circuit to each ICP antenna for more efficient power deliverly Distributions of ion density and electron temperature are measured in terms of chamber pressure, gas flow rate and RF power . By adjusting the power distribution among the four helical resonator units, argon plasma density of higher than 10$\^$17/㎥ with the uniformity of better than 7％ can be obtained in the 620 ${\times}$ 620$\textrm{mm}^2$ chamber.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.2
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• pp.262-267
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• 2008

Plasma immersion ion beam (PIIB) nitriding process is an environmentally benign and cost-effective process, and offers the potential of producing high dose of nitrogen ions in a way of simple, fast and economic technique for the high plasma flux treatment of large surface area with nitrogen ion source gas. In this report PIIB nitriding technique was used for nitriding on austenite stainless steel of AISI304 with plasma treatment at $250{\sim}500^{\circ}C$ for 4 hours, and with the working gas pressure of $2.67{\times}10^{-1}$ Pa in vacuum condition. This PIIB process might prove the advantage of the low energy high flux of ion bombardment and enhance the tribological or mechanical properties of austenite stainless steel by nitriding, Furthermore, PIIB showed a useful surface modification technique for the nitriding an irregularly shaped three dimensional workpiece of austenite stainless steel and for the improvement of surface properties of AISI 304, such as hardness and strength

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.60-60
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• 2000

The adhesion interface formation between copper and poly(ethylene terephthalate)(PET), poly(methyl methacrylate)(PMMA) and Polyimide films was treated using Ion assisted reaction system to sequential sputter deposition by High-Frequency ion source. The ion beam modification system used a new type of low power HF ion thruster for space application as new low thruster electric propulsion system. Low power HF ion thruster with diameter 100mm gives the opportunity to obtain beams of Ar+ with currents 20~150 mA (current density 0.5~3.5 mA/cm2) and energy 200~2500eV at HF power level 10~150 W. Using Ar as a working gas it is possible to obtain thrust within 3~8 mN. Contact angles for untreated films were over 95$^{\circ}$ and 80 for Pet, 10o for PMMA and 12o for PI samples as a condition of ion assisted reaction at the ion dose of 10$\times$1016 ions/cm2, the ion beam potential of 1.2 keV and 4 ml/min for environmental gas flow rate. 900o peel tests yielded values of 15 to 35 for PET, 18 to 40 and 12 to 36 g/min. respectively. High resolution X-ray photoelectron spectrocopy is the Cls region for Cu metal on these polymer substrates showed increases in C=O-O groups for polymide, whereas PET and PMMA treated samples showed only C=O groups with increase the ion dose. Finally, unstable polymer surface can be changed from hydrophobic to hydrophilic formation such as C-O and C=O that were confirmed by the XPS analysis, conclusionally, the ion assisted reaction is very effective tools to attach reactive ion species to form functional groups on C-C bond chains of PET, PMMA and PI.

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.2
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• pp.136-141
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• 2005

Li-doped NiO was synthesized by molten salt method. $LiNO_3$-LiOH flux was used as a source for Li doping. $NiCl_2$ was added to the molten Li flux and then processed to make the Li-doped NiO material. Li:Ni ratios were maintained from 5:1 to 30:1 during the synthetic procedure and the Li doping amount of synthesized materials were found between 0.086-0.190 as a Li ion to Ni ion ratio. Li doping did not change the basic cubic structural characteristics of NiO as evidenced by XRD studies, however the lattice parameter decreased from 0.41769nm in pure NiO to 0.41271nm as Li doping amount increased. Hydrogen gas sensors were fabricated using these materials as thick films on alumina substrates. The half surface of each sensor was coated with the Pt catalyst. The sensor when exposed to the hydrogen gas blended in air, heated up the catalytic surface leaving rest half surface (without catalyst) cold. The thermoelectric voltage thus built up along the hot and cold surface of the Li-doped NiO made the basis for detecting hydrogen gas. The linearity of the voltage signal vs $H_2$ concentration was checked up to 4% of $H_2$ in air (as higher concentrations above 4.65% are explosive in air) using Li doped NiO of Li ion/Ni ion=0.111 as the sensor material. The response time T90 and the recovery time RT90 were less than 25 sec. There was minimum interference of other gases and hence $H_2$ gas can easily be detected.