• 한국초전도ㆍ저온공학회논문지
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• 제22권2호
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• pp.21-25
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• 2020

We investigated the flux pinning property of GdBa₂Cu₃O_7-x (GdBCO) films on top of La_0.7Sr_0.3MnO₃ (LSMO) nanoparticles deposited by a surface decoration. Both GdBCO films and LSMO nano particles were deposited by pulsed laser deposition and the number of laser pulses were varied from 80 to 320 in order to control the density of the LSMO nanoparticles. The magnetization data at 77 K showed that the critical current density (J_c) was enhanced in all of the GdBCO films with LSMO nanoparticles and that the J_c enhancement was found to be inversely proportional to the LSMO nanoparticle density. Structural analyses revealed that LSMO nanoparticles induce a compressive strain in the GdBCO films resulting in a disordering in the CuO₂ plane. Therefore, the enhanced flux pinning property in the GdBCO with LSMO nanoparticles was attributed to the competing effect between the increase of pinning centers and the increase of compressive strain in the superconducting phase.

• 동력기계공학회지
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• 제5권1호
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• pp.89-96
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• 2001

Decorative property of chromium deposition from oxalic acid bath containing chromium oxide and ammonium sulfate, has been examined over a wide range of bath compositions and plating conditions. The followings were determined as optimum bath composition, $CrO_3\;200{\sim}250g/{\ell},\;H_2C_2O_4{\cdot}2H_2O\;500{\sim}700g/{\ell},\;(NH_4){_2}SO_4\;40{\sim}120g/{\ell}$, and operation conditions; pH $2.0{\sim}2.5$, current density of $15{\sim}250Adm^2 $ at the bath temperatures of $30{\sim}80^{\circ}C$. Bright chromium deposits were obtained over a wide range of ammonium sulfate concentration, bath temperature, and current density. The current efficiency decreased with increasing current density and bath pH, and increased with Increasing bath temperature. The highest current efficiency was obtained in the bath containing $80g/{\ell}$ of ammonium sulfate. Bright chromium deposits were not obtained at conditions of all the highest current efficiencies.

• 한국전기전자재료학회논문지
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• 제16권1호
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• pp.53-59
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• 2003

Using Platinum-silicide (PtSi) formed between silicon substrate and carbon film, we have improved the field emission of electrons from carbon films. Pt films were deposited on n-Si(100) substrates at room temperature by DC sputter technique. After deposition, these PtSi thin films were annealed at 400 ~ $600^{\circ}C$ in a vacuum chamber, and the carbon films were deposited on those Pt/Si substrates by laser ablation at room temperature. The field emission property of C/Pt/Si system is found to be better than that of C/Si system and it is showed that property was improved with increasing annealing temperature. The reasons why the field emission from carbon film was improved can be considered as follows, (1)the resistance of carbon films was decreased due to graphitization, (2)electric field concentration effectively occurred because the surface morphology of carbon film deposited on Pt/si substrates with rough surface, (3)it is showed that annealing induced reaction between Pt film and Si substrate, as a consequence that the interfacial resistance between Pt film and Si substrate was decreased.

• 한국태양에너지학회 논문집
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• 제39권1호
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• pp.33-40
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• 2019

Al-doped ZnO (AZO) thin films were synthesized on Si(100) wafers via plasma enhanced metal organic chemical vapor deposition (PE-MOCVD) method using diethyl zinc (DEZ) and N-methylpyrrolidine alane (MPA) as precursors. Effects of Al/Zn mixing ratio, plasma power on the surface morphology, crystal structure, and electrical property were investigated with SEM, XRD and 4-point probe measurement respectively. Growth rate of the film decreased slightly with increasing the Al/Zn mixing ratio, however electrical property was enhanced and resistivity of the film decreased greatly about 2 orders from $9.5{\times}10^{-1}$ to $8.0{\times}10^{-3}{\Omega}cm$ when the Al/Zn mixing ratio varied from 0 to 9 mol%. XRD analysis showed that the grain size increased with increasing the Al/Zn mixing ratio. Growth rate and electrical property were enhanced in a mild plasma condition. Resistivity of AZO film decreased down to $7.0{\times}10^{-4}{\Omega}cm$ at an indirect plasma of 100 W condition which was enough value to use for the transparent conducting oxide (TCO) material.

• 한국재료학회지
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• 제13권3호
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• pp.185-190
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• 2003

Titanium dioxide films were prepared by RF sputtering method on glass for various oxygen partial pressures at power 270 W. The crystal structure, photocatalytic property and the hydrophilicity of $TiO_2$thin film the deposition conditions were investigated. Crystallized anatase phase was observed in $TiO_2$film deposited at the ratio of oxygen partial pressure 10% and 20% for 2 hrs. As the increase of deposition time, the grain size and void size of $TiO_2$film have increased and also $V_2$films have been good crystallinity. The ultraviolet-visible light absorption of $TiO_2$films was increased with increasing of deposition time and occured chiefly at the wavelength between 280 and 340 nm. The absorption band was shifted to a longer wave length as deposition time increased. Water contact angle on the X$TiO_2$film of anatase structure was decreased with increasing ultraviolet illumination time and became lower than $11^{\circ}$ from $83^{\circ}$. When hydrophilic $TiO_2$film changed by enough ultraviolet illumination was stored in the dark, the film surface gradually turned to hydrophobic state.

• 한국분말재료학회지
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• 제23권5호
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• pp.384-390
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• 2016

Tri-isotropic (TRISO) coatings on zirconia surrogate beads are deposited using a fluidized-bed vapor deposition (FB-CVD) method. The silicon carbide layer is particularly important among the coated layers because it acts as a miniature pressure vessel and a diffusion barrier to gaseous and metallic fission products in the TRISO-coated particles. In this study, we obtain a nearly stoichiometric composition in the SiC layer coated at $1400^{\circ}C$, $1500^{\circ}C$, and $1400^{\circ}C$ with 20 vol.% methyltrichlorosilane (MTS), However, the composition of the SiC layer coated at $1300-1350^{\circ}C$ shows a difference from the stoichiometric ratio (1:1). The density decreases remarkably with decreasing SiC deposition temperature because of the nanosized pores. The high density of the SiC layer (${\geq}3.19g/cm^2$) easily obtained at $1500^{\circ}C$ and $1400^{\circ}C$ with 20 vol.% MTS did not change at an annealing temperature of $1900^{\circ}C$, simulating the reactor operating temperature. The evaluation of the mechanical properties is limited because of the inaccurate values of hardness and Young's modulus measured by the nano-indentation method.

• 한국재료학회지
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• 제9권11호
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• pp.1148-1152
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• 1999

본 연구에서는 기존에 알려진 구리 전구체와 새롭게 개발된 전구체인 hfac (hexafluoroacetylacetonate) Cu(I) DMB (3,3-dimethyl-1-butene)를 비교 평가해보았다. (Hfac)Cu(I) (DMB)의 증가압은 $40^{\circ}C$에서 3 torr 정도로 기존에 잘 알려진 (hfac)Cu(I) vinyltrimethylsilane (VTMS) 보다 10배 정도 높은 것으로 나타났으며 그럼에도 불구하고 상당히 안정하여 $65^{\circ}C$에서 일주일 이상 가열하여도 변하지 않았다. 이 전구체로 100-$280^{\circ}C$에서 구리 박막을 증착할 수 있었으며 150-$250^{\circ}C$온도 범위에서 2.0$\mu\Omega$-cm의 순수한 구리 박막을 얻었다. 구리 박막의 증착 속도는 기존의 전구체보다 7~8배 정도 높은 것으로 나타났다.

• 한국전기전자재료학회논문지
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• 제22권5호
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• pp.425-430
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• 2009

$ZrO_2$ film was deposited by facing target sputtering (FTS) system on polyethylene naphthalate (PEN) substrate as a gas barrier layer for flexible organic light emitting devices (FOLEDs), In order to control the heat of the FTS system caused by the ion bombardment in the cathode compared with the conventional sputtering system, the process characteristics of the FTS apparatus are investigated under various sputtering conditions such as the distance between two targets ($d_{TT}$), the distance between the target and the substrate ($d_{TS}$), and the deposition time. The $ZrO_2$ film by the FTS system can reduce the damage on the films because the ion bombardment with high-energy particles like gamma-electrons, Moreover, the $ZrO_2$ film with optimized condition ($d_{TT}$=140 mm) as a function of the distance from center to edge showed a very uniform thickness below 5 % for a deposition time of 3 hours, which can improve the interface property between the anode and the plastics substrate for flexible displays, It is concluded that the $ZrO_2$ film prepared by the FTS system can be applied as a gas barrier layer or an interlayer between the anode and the plastic substrate with good properties of an uniform thickness and a low deposition-temperature.

• 한국자기학회지
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• 제15권1호
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• pp.21-24
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• 2005

강자성, 초거대자기저항체인 $La_{0.67}Sr_{0.33}MnO_{3}$ 타겟을 이용하여 248nm의 파장을 갖는 KrF 엑시머 레이저를 사용한 PLD법으로 박막으 제작하고, 강유전체 물질인 $PbZr_{0.52}Ti_{0.48}O_{3}$ 물질을 spin coating 방법으로 제조하였다. Pt 기관(111)위에 125 mtorr의 산소분압으로 증착한 rhombohedral 구조를 갖는 LSMO 박막을 증착하고 그 위에 PZT 물질을 증착한 결과 LSMO, PZT en 물질 모두 단일상으로 [111]방향으로서의 성장하였음을 알 수 있었다. AFM(atomic force micrscope) data 및 SEM(scanning electron microscope) data를 바탕으로 매우 균질한 박막을 얻었음을 알 수 있었으며, 이때의 자기적 성질 및 전기적 성질은 각각 강자성적인 성질 및 강유전체적인 성향을 나타내었다. 이러한 결과를 가지고 박막증착에 있어서 서로간의 결정구조가 미치는 영향과 다른 경향에 대한 조절이 가능함을 알 수 있었다.

• 한국전기전자재료학회논문지
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• 제27권8호
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• pp.516-521
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• 2014

An excellent hydrophobic surface has a high contact angle over 147 degree and the contact angle hysteresis below $5^0$ was produced by using roughness combined with hydrophobic PTFE coatings, which were also confirmed to exhibit an extreme adhesion to glass substrate. To form the rough surface, the glass was etched by Ar-plasma. A very thin PTFE film was coated on the plasma etched glass surface. Roughness factors before or after PTFE coating on the plasma etched glass surface, based on Wensel's model were calculated, which agrees well with the dependence of the contact angle on the roughness factor is predicted by Wensel's model. The PTFE films deposited on glass by using a conventional rf-magnetron sputtering. The glass substrates were etched Ar-plasma prior to the deposition of PTFE. Their hydrophobicities are investigated for application as a anti-fouling coating layer on the screen of displays. It is found that the hydrophobicity of PTFE films mainly depends on the sputtering conditions, such as rf-power, Ar gas content introduced during deposition. These conditions are closely related to the deposition rate or thickness of PTFE film. Thus, it is also found that the deposition rate or the film thickness affects sensitively the geometrical morphology formed on surface of the rf-sputtered PTFE films. In particular, 1,950-nm-thick PTFE films deposited for 30 minute by rf-power 50 watt under Ar gas content of 20 sccm shows a very excellent optical transmittance and a good anti-fouling property and a good durability.