• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1379-1382
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• 1997

Diamond-like carbon(DLC) thin films are produced by using a filtered cathodic vacuum arc(FCVA) deposition system. Different magnetic components, namely steering, focusing, and filtering plasma-optic systems, are used to achieve a stable arc plasma and to prevent the macroparticles from incorporating into the deposited films. Effects of magnetic fields on plasma behavior and film deposition are examined. The carbon ion energy is found to be varied by applying a negative (accelerating) substrate bias voltage. The deposition rate of DLC films is dependent upon magnetic field as well as substrate bias voltage and at a nominal deposition condition is about $2{\AA}/s$. The structural properties of DLC films, such as internal stress, relative fraction of tetrahedral($sp^3$) bonds, and surface roughness have also been characterized as a function of substrate bias voltages and partial gas($N_2$) pressures.

• Journal of the Korean Ceramic Society
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• v.45 no.9
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• pp.556-560
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• 2008

The effects of Nb and Co ion substitution on the dielectric and magnetic properties of the multiferroic $BiFeO_3$ thin films have been investigated. Heteroepitaxial $BiFeO_3$ thin films were deposited by Pulsed Laser Deposition method. Nb substitution decreased the leakage current by 6 orders of magnitude and Co substituted $BiFeO_3$ thin films showed an enhanced magnetization, 2 times larger than that of un-substituted $BiFeO_3$. Through the co-substitution of Co and Nb, $BiFeO_3$ thin films with a low leakage current and an enhanced magnetization could be obtained.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.470-473
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• 1995

We have constructed an apparatus for in sity measurement of stress of the film prepared by sputtering using an optical noncontact displacement detector. A Change of the gap distance between the detector and the substrate, caused by stress of a deposited film, was detected by a corresponding change of the reflectivity. The sensitivity of the displacement detector was $5.9\;{\mu}V/{\AA}$ and thus, it was turned out to be good enough to detect stress caused by deposition of a monoatomic layer. The apparatus was applied to in situ stress measurements of Co/X(X=Pd or Pt) multilayer thin films prepared on the glass substrates by dc magnetron sputtering. At the very beginning of the deposition, both Co and X sublayers have subjected to their own intrinsic stresses. However, when the film was thicker than about $100{\AA}$, constant tensile stress in the Co sublayer and compressive stress in the X sublayer were observed, which is believed to be related to a lattice mismatch between the matching planes of Co and X.

• Journal of the Korean Vacuum Society
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• v.4 no.S2
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• pp.24-29
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• 1995

The magnetic amd magneto-optical(MO)properties of Co-based multilayered(ML)films are known to vary sensitively according to the manufacturing methods and the film microstructures. Co/Pd and Co/Pt ML films with ultrathin layers of Co were prepared by alternating deposition in an ultrahigh-vacuum physical-vapor-deposition system. The individual layer thicknesses of the samples were estimated making use of the angular positions of x-ray diffraction peaks. The magnetic and MO properties were investigated, and correlated systematically to the structural parameters of the films. A Kerr spectrometer was self-manufactured to measure the MO properties such as Kerr rotation angle, ellipticity and reflectivity. The rms surface roughness was also measured using atomic force microscopy. Some of the samples showed good properties for MO medium, such as large perpendicular magnetic anisotropy and Kerr rotation, and perfect squareness of the magnetic hysteresis loop.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.1
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• pp.11-16
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• 2001

CuNi alloy films are deposited by co-sputtering of dual targets (Cu and Ni, respectively). Effects of the co-sputtering conditions, such as powers applied to the targets, deposition pressures, and substrate temperatures, on the structural and electrical properties of deposited films are systematically investigated. The composition ratio of Ni/Cu is almost linearly decreased by increasing the DC power applied to the Cu target from 25.6 W to 69.7 W with the RF power applied to the Ni target unchanged(140 W). it is noted that the chamber pressure during deposition and the film thickness give rise to a change of the Ni/Cu ratio within the films deposited. The former may be due to a higher sputtering yield of Cu atom and the latter due to the re-sputtering phenomenon of Cu atoms on the surface of deposited film. The film deposited at higher pressures or at lower substrate temperatures have a smaller crystallite size, a higher electrical resistivity, and much more voids. This may be attributed to a lower surface mobility of sputtered atoms over the substrate.

• Carbon letters
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• v.8 no.1
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• pp.12-16
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• 2007

Molecular sieving carbon (MSC) for separating $O_2-N_2$ and $CO_2-CH_4$ has been prepared through chemical vapor deposition (CVD) of methane and benzene on activated carbon spheres (ACS) derived from polystyrene sulfonate beads. The validity of the material for assessment of molecular sieving behavior for $O_2-N_2$ and $CO_2-CH_4$ pair of gases was assessed by the kinetic adsorption of the corresponding gases at $25^{\circ}C$. It was observed that methane cracking on ACS lead to deposition of carbon mostly in whole length of pores rather than in pore entrance, resulting in a reduction in adsorption capacity. MSC showing good selectivity for $CO_2-CH_4$ and $O_2-N_2$ separation was obtained through benzene cracking on ACS with benzene entrantment of $0.40{\times}10^{-4}\;g/ml$ at cracking temperature of $725^{\circ}C$ for a period of 90 minutes resulting in a selectivity of 3.31:1.00 for $O_2-N_2$ and 8.00:1.00 for $CO_2-CH_4$ pair of gases respectively.

• Journal of Magnetics
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• v.19 no.2
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• pp.121-125
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• 2014

$CoFe_2O_4(CFO)/BaTiO_3(BTO)/CoFe_2O_4(CFO)$ multilayered thin films were deposited on $Pt/TiO_2/SiO_2/Si$ substrates by the pulsed laser deposition (PLD) system with KrF excimer laser (${\lambda}=248nm$). BTO, CFO, BTO/CFO and CFO/BTO/CFO structured thin films were prepared and their crystal structures and microstructures, as well as their magnetic and magneto-electrical properties, were studied. The C-V characteristics of these multilayered thin films with different capacitor structures were obtained to confirm the change in their capacitances under a magnetic field. Finally, the capacitance of the CFO/BTO/CFO thin film as a function of bias voltage under an in-plane magnetic field of 1,000 Oe increased to 951.04 pF at 1 MHz, from 831.90 pF measured under no magnetic field, indicating 14.3% increase in magnetocapacitance.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.140.2-140.2
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• 2013

Strong metal-support interaction effect is an important issue in determining the catalytic activity for heterogeneous catalysis. In this work, we report the catalytic activity of $Au/TiO_2$, $Au/Al_2O_3$, and $Au/Al_2O_3-CeO_2$ nanocatalysts under CO oxidation fabricated by arc plasma deposition (APD), which is a facile dry process with no organic materials involved. These catalytic materials were characterized by transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) and $N_2$-physisorption. Catalytic activity of the materials has measured by CO oxidation using oxygen, as a model reaction, in a micro-flow reactor at atmospheric pressure. Using APD, the catalyst nanoparticles were well dispersed on metal oxide powder with an average particle size (3~10 nm). As for catalytic reactivity, the result shows $Au/Al_2O_3-CeO_2$ nanocatalyst has the highest catalytic activity among three samples in CO oxidation, and $Au/TiO_2$, and $Au/Al_2O_3$ in sequence. We discuss the effects of structure and metal-oxide interactions of the catalysts on catalytic activity.

• Journal of the Korean Ceramic Society
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• v.28 no.1
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• pp.1-10
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• 1991

Zirconium dioxide(ZrO2) thin films have been deposited by chemical vapor deposition technique involving the application of gas mixture of ZrCl4, and H2O into silicon wafers. The relationships between the deposition rate and various reaction parameters such as the deposition time, the gas flow rate, the deposition temperature, and the composition of reactant gases were studied. The film was identified as nearly stoichiometric monoclinic ZrO2. The apparent activation energy is about 19Kcal/mole at surface chemical reaction controlled region. The deposition rate is mainly influenced by the H2O-forming reacting between CO2 and H2.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.336-339
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• 2007

The enhanced control of OLED deposition processes by Organic Vapor Phase Deposition $(OVPD^{(R)})$ is discussed. $OVPD^{(R)}$ opens a wide space of process control parameters. It allows the accurate and individual control of deposition layer properties like morphology and precise mixing of multi component layers (co-deposition) in comparison to conventional deposition manufacturing processes like e. g. VTE (vacuum thermal evaporation).