• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.869-873
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• 2004

[ $Sr_xBa_{1-x}Nb_2O_6$ ] (SBN, $0.25{\leq}x{\leq}0.75$) ceramic is a ferroelectric material with tetragonal tungsten bronze (TTB) type structure, which has a high pyroelectric coefficient, piezoelectric, and a photo refractive properties. In this study, SBN60(x=0.6) thin film was manufactured by ion beam sputtering technique. Using the prepared SBN60 target in $Ar/O_2$ atmosphere as-deposited SBN60 thin film on Pt(100)/$TiO_2/SiO_2/Si$ substrate crystallization and orientation behavior as well as electric properties of SBN60 thin film were examined. SBN60 deposition up to $3000{\AA}$ in thickness, SBN60 thin film was heat-treated at $650^{\circ}C{\sim}800^{\circ}C$. The orientation was shown primarily along (001) plane from XRD pattern where working pressure was $4.3{\times}10^{-4}$ torr. The deposited layer was uniform, preferred orientatin and crystallization behavior resulted in the change of $O_2$ ratio was observed. In electric propertie of Pt/SBN60/Pt thin film capacitor remnant polarization (2Pr) value was $10{\mu}C/cm^2$, the coercive filed (Ec) 50 kV/cm, and the dielectric constant 615, respectively.

• Transactions on Electrical and Electronic Materials
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• 제6권6호
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• pp.245-248
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• 2005

The physical and electrical properties of polycrystalline $\beta$-SiC were studied according to different nitrogen doping concentration. Nitrogen-doped SiC films were deposited by LPCVD(1ow pressure chemical vapor deposition) at $900^{\circ}C$ and 2 torr using $100\%\;H_2SiCl_2$ (35 sccm) and $5 \%\;C_2H_2$ in $H_2$(180 sccm) as the Si and C precursors, and $1\%\;NH_3$ in $H_2$(20-100 sccm) as the dopant source gas. The resistivity of SiC films decreased from $1.466{\Omega}{\cdot}cm$ with $NH_3$ of 20 sccm to $0.0358{\Omega}{\cdot}cm$ with 100 sccm. The surface roughness and crystalline structure of $\beta$-SiC did not depend upon the dopant concentration. The average surface roughness for each sample 19-21 nm and the average surface grain size is 165 nm. The peaks of SiC(111), SiC(220), SiC(311) and SiC(222) appeared in polycrystalline $\beta$-SiC films deposited on $Si/SiO_2$ substrate in XRD(X-ray diffraction) analysis. Resistance of nitrogen-doped SiC films decreased with increasing temperature. The variation of resistance ratio is much bigger in low doping, but the linearity of temperature dependent resistance variation is better in high doping. In case of SiC films deposited with 20 sccm and 100 sccm of $1\%\;NH_3$, the average of TCR(temperature coefficient of resistance) is -3456.1 ppm/$^{\circ}C$ and -1171.5 ppm/$^{\circ}C$, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.331-332
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• 2008

Couplings between electric, magnetic, and structural order parameters result in the so-called multiferroic phenomena with two or more ferroic phenomena such as ferroelectricity, ferromagnetism, or ferroelasticity. The simultaneous ferroelectricity and ferromagnetism (magnetoelectricity) permits potential applications in information storage, spintronics, and magnetic or electric field sensors. The perovskite BiFeO3(BFO) is known to be antiferromagnetic below the Neel temperature of 647K and ferroelectric with a high Curie temperature of 1043K. It exhibits weak magnetism at room temperature due to the residual moment from a canted spin structure. It is likely that non-stoichiometry and second-phase formation are the factors responsible for leakage current in BFO. It has been suggested that oxygen non-stoichiometry leads to valence fluctuations of Fe ions in BFO, resulting in high conductivity. To reduce the large leakage current of BFO, one attempt is to make donor-doped BFO compounds and thin films. In this study, (Bi1-x,Ndx)(Fe1-y,Tiy)O3 thin films have been deposited on Pt(111)/TiO2/SiO2/Si substrates by pulsed laser deposition. The effect of dopants on the phase evolution and surface morphology are analyzed. Furthermore, electrical and magnetic properties are measured and their coupling characteristics are discussed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전기물성,응용부문
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• pp.109-110
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• 2006

In bio applications, high temperature coefficient of resistance (TCR) at $30^{\circ}C{\sim}40^{\circ}C$ is especially important for a temperature sensor. In this work, single phase-vanadium dioxide ($VO_2$) thin films for temperature sensor were fabricated by reactive DC magnetron sputtering and post-annealing method. VOx thin films deposited by reactive sputtering in a controlled $Ar/O_2$ atmosphere can be transformed into single phase-$VO_2$ films by post-annealing in $N_2$ atmosphere. The grown $VO_2$ thin films have a moderate resistance at room temperature and very high TCR at room temperature and transition temperature, respectively 2.88%/K and 15.8%/K. A detailed structural characterization is performed by SEM, XRD and RBS. SEM morphology image indicates that grains of fabricated $VO_2$films are homogeneous and ball-like in shape. A fact that the films contain only single phase-$VO_2$ is obtained by XRD and RBS analysis. After deposition, the sensors were fabricated by micromachining technology. Silicon nitride membrane and black nickel were used for a thermal isolation structure and absorption layer. In the vicinity of room temperature, the TCR of sensors was enough high to apply for bio sensors.

• 전기학회논문지
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• 제58권11호
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• pp.2209-2213
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• 2009

$REBa_{2}Cu_{3}O_{7-d}$(REBCO) coated conductors(REBCO CCs) have been studied for electric power applications which require high current density wires. As long as the critical transition temperature(Tc) is concerned, REBCO CCs with large $RE^{3+}$ ions have been expected to have better current transport properties than those with smaller $RE^{3+}$ ions. For this reason, REBCO's with large $RE^{3+}$ ions which include GdBCO, NdBCO and SmBCO have been mainly considered as the superconducting layer of CCs. On the other hand, REBCO's with smaller $RE^{3+}$ions are expected to have advantages in the fabrication process of CCs because of the lower melting temperature. But it has not yet been made clear which REBCO is the most suitable for the superconducting layer of CCs. In this study, we investigated the current transport properties of REBCO CCs with small $RE^{3+}$ ion and advantages of using that in the CC fabrication process. Thin films of TmBCO, which has smaller $RE^{3+}$ion than most other $RE^{3+}$ ions, were fabricated on buffered metal substrate as the superconducting layer of CC by PLD process. TmBCO CC shows critical current density (Jc (77 K, sf) = $2.3\;MA/cm^2$) high enough to be utilized for application in electric power devices. Compared with previous experiments using the same PLD system, deposition temperature was approximately $20^{\circ}C$ lower than NdBCO thin films on buffered metal substrates.

• 한국진공학회지
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• 제9권3호
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• pp.233-236
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• 2000

TFT-LCD(thin film transistor-liquid crystal display) 패널의 데이터 배선 재료로 사용하기 위하여 AlW(3 wt%)의 Al합금 박막을 dc 마그네트론 스퍼터링 방법으로 유리 기판에 증착하여 열처리전과 열처리 후의 박막 특성을 조사하였다. 또한 TFT-LCD의 식각 공정상에서 발생할 수 있는 chemical attack에 대한 저항성을 확인하기 위하여 순환전압전류법(cyclic voltammetry)을 사용하여 Ag/AgCl 전극에 대한 ITO와 AlW alloy의 전극 전위를 측정하였다. 증착된 박막을 $350^{\circ}C$에서 20분간 열처리하였을 때 AlW 박막은 비저항이 감소하였고 약 $11\;{\mu\Omega}cm$의 다소 높은 비저항 특성을 보였다. 주사전자현미경(SEM)과 원자힘현미경(AFM)으로 표면을 분석한 결과 좋은 힐록방지 특성을 보임을 알 수 있었다. 순환전압전류법을 사용하여 측정한 Ag/AgCl 에 대한 ITO의 전극 전위은 약 -1.8V이었고, AlW alloy의 전위 전극은 W의 wt.%가 3% 이상이었을 때, ITO의 전극 전위보다 작게 나타났다. 따라서 측정된 특성 값을 볼 때 AlW(over 3 wt.%) 박막은 data bus line으로 사용할 수 있는 것으로 나타났다.

• Transactions on Electrical and Electronic Materials
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• 제13권2호
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• pp.93-97
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• 2012

In this study, the fabrication and the characteristic analyses of OLED using in-situ passivation are investigated. OLEDs represent a disadvantage in decreasing its life due to the degradation caused by the penetration of moisture and oxygen. After the fabrication of OLED, an in-situ passivation method for inorganic thin films is developed. A process that uses PECVD method which can apply a vapor deposition process at room temperature is also developed. Changes in the degradation and electric characteristics of OLEDs are also analyzed by applying $SiO_2$ and SiNx thin films to OLED as a passivation layer. By applying the fabricated thin film to OLEDs as a passivation layer, the moisture penetration in a single layer film is ensured below $1{\times}10^{-2}\;g/m^2.day$. This leads to the improvement of such degradation characteristics in the application of multilayer films.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.418-418
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• 2012

Synthesis of nanocrystalline diamond powder was investigated via a gas-to-particle scheme using the hot filament chemical vapor deposition. Effect of substrate surface seeding by nano diamond powder, and that of the electrical conductance of the substrate were studied. The substrate temperature, methane content in the precursor gas, filament-substrate distance and filament temperature were $670^{\circ}C$, 5% methane in hydrogen, 10 mm and $2400^{\circ}C$, respectively. The powder formation by gas-to-particle mechanism were greatly enhanced by the substrate seeding by the nano diamond powder. It was attributed to the removal of the electrostatic force between the substrate and the seeded nano diamond particle by the thermal electron shower from the hot filament, via the depolarization of the substrate surface or the attached diamond powder and subsequent levitation into the gas phase to serve as the gas-phase nucleation site. The powder formation was greatly favoured by the conducting substrate relative to the insulating substrate, which proved the actual effect of the electric static force in the powder formation.

• Ocean and Polar Research
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• 제22권2호
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• pp.57-67
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• 2000

Time-selective self-triggering water sampler, AUTTLE developed by Jin et al. (1999) has been improved in order to prevent pre-deposition of suspended sediments (SS) before sampling. By using two solenoids, the improved sampler is able to be moored or deployed with inclination. Its position is changed to horizontal position by activating the first solenoid, and then the endcaps of the sampling bottle are closed by the second solenoid that is driven three times to minimize possible failure of sampling. An external control unit for setting sampling time has been also constructed. Additionally, the electric circuit housing of the sampler has been modified to be detached from the sampling bottle when operating manually. Its performance has been confirmed through flume tests and a field experiment. It will serve as a valuable tool in the various fields of oceanography and environmental engineering, especially where seawater sampling synchronized at several sites and/or the information in storm period is important.

• 한국기계가공학회지
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• 제12권4호
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• pp.123-130
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• 2013

Zirconia is well known in industrial applications for its mechanical characteristics. DLC (diamond-like carbon) have high elastic modulus, high electric resistivity, high dielectric constant, high wear resistance, low friction coefficient, bio compatibility, chemically inert and thermally stable. Because of all these physical and chemical properties these types of coatings have become key procedure for thin coating. Friction coefficient of DLC films is already evaluated and the current work is a further advancement by calculating the fracture toughness and wear resistance of these coatings. In the present study DLC thin film coatings are developed on $ZrO_2$ alloy surface using Plasma Enhanced Chemical Vapor Deposition (PECVD) method. Vicker hardness test is employed and it was concluded that, DLC coatings increase the Vickers hardness of ceramics.