• 한국진공학회지
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• 제17권2호
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• pp.130-137
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• 2008

$La_{0.7}Sr_{0.3}MnO_3$ 박막을 rf 마그네트론 스퍼터를 이용하여 챔버 내 산소가스유량비를 0, 40, 80 sccm 으로 조절하고 후열처리 공정 없이 기판온도를 $350^{\circ}C$로 유지하면서 $SiO_2$/Si(100) 및 Si(100) 기판에 증착하였다. 증착된 $La_{0.7}Sr_{0.3}MnO_3$ 박막은 $SiO_2$/Si(100), Si(100) 기판 모두 (100), (110), (200)면을 갖는 polycrystalline 상태였으며, oxygen flow rate이 증가함에 따라 박막의 grain size가 증가하였다. 증가되는 grain size로 인하여 grain boundary가 감소하였고 따라서 높은 oxygen flow rate에서 증착된 박막은 면저항이 감소하는 현상을 나타내었다. $SiO_2$/Si 기판과 Si 기판에 증착된 LSMO 박막의 TCR 값은 약 -2.0 $\sim$ -2.2%를 나타내었다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 제33회 추계학술대회논문집
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• pp.119-122
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• 2009

본 연구는 친환경 추진제인 과산화수소($H_2O_2$)와 케로신을 추진제로 하는 액체 로켓 엔진에서의 막냉 각 장치 개발을 목적으로 이를 위하여 막냉각링을 설계/제작하고, 수류 시험을 통해 분무 특성과 공급 유량을 확인하였다. 또한 설계/제작된 막냉각링의 성능 예측을 위하여 열해석을 수행하였다. 수류 실험 결과 설계 유량(42.25g/s)이 공급됨을 확인하였고, 상대적으로 유속이 빠르고 홀 개수가 많은 막냉각링이 더 좋은 분무패턴을 보임을 확인하였다. 또한 열해석 결과 설계된 막냉각링이 충분한 냉각 성능을 가짐을 확인하였다.

• 한국세라믹학회지
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• 제44권11호
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• pp.645-649
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• 2007

The $La_{0.7}Sr_{0.3}MnO_3$ was deposited on $SiO_2/Si$ substrate by RF magnetron sputtering. The oxygen gas flow rate was changed from 0 to 80 sccm and the substrate temperature was $350^{\circ}C$. The oxygen gas flow rate was changed to control the growth orientation and crystalline state of the film. Relatively high TCR (temperature coefficient of resistance) value (-2.33%/K) was obtained when comparing with the reported values of the films prepared by using high substrate anneal temperature. The decrease in the sheet resistance and TCR value were observed when grain size of the film increased with the increase of oxygen gas flow rate.

• 한국재료학회지
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• 제9권2호
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• pp.144-148
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• 1999

We have studied the deposition characteristics of thick silicon dioxide film on Si substrate by $O_3$/TEOS APCVD(Atmospheric Pressure Chemical Vapor Deposition). The effect of deposition parameters such as the distance between showerhead and substrate, deposition temperature, TEOS flow rate and $O_3$/TEOS ratio on deposition rate, surface morphology, and properties of films as investigated. As deposition temperature increased, deposition rate decreased but the surface morphology and adhesion of film to substrate improved. As the distance between showerhead and substrate decreased, the deposition rate increased. Etching rate using the BOE increased as TEOS flow rate increased, but was independent of$ O_3$/TEOS ratio. Deposition rate of $5\mu\textrm{m}$/hour was obtained under the condition that the distance between showerhead and substrate was 5mm and the deposition temperature was $370^{\circ}C$.

• 한국물환경학회지
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• 제20권5호
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• pp.488-493
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• 2004

The effects were examined from several conditions of $TiO_2$ photocatalysis reaction to phenols degradation by changing it's reacting conditions such as phenol concentration, pH, $TiO_2$ concentration, $H_2O_2$ concentration, flow rate, and intensity of ultraviolet rays. Phenol degradation was more efficient in low concentration of phenol, neutral pH. Phenol degradation appeared to increase as concentration of $TiO_2$ photocatalyst, that of $H_2O_2$ and intensity of ultraviolet rays increased. As $TiO_2$ dosage increased, initial rate constant k linearly increased. When $H_2O_2$ was injected more than optimum, phenol removal rate didn't increase in proportional to the change of $H_2O_2$ concentration as OH radicals was being consumed. When flow rate is less than $4.75m^3/m^2$ day, phenol removal efficiency appeared to decrease as ultraviolet rays transmission rate becomes low by $TiO_2$ suspension coated in photo reaction column. Meanwhile, initial rate constant according to light intensity change in less than $25mW/cm^2$ appeared to be in proportion to light intensity ($mW/cm^2$) Removal efficiency decreased about 12% after 180 minutes of reaction time while showed stable removal efficiency of 100% after 300 minutes when using regenerated $TiO_2$.

• 한국세라믹학회지
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• 제31권2호
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• pp.206-212
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• 1994

Effects of the film deposition process parameters on the properties such as deposition rate, etch rate, refractive index, stress and step coverage of plasma enhanced chemical vapor deposited (PECVD) tetraethylorthosilicate glass (TEOS) SiO2 film were investigated and analysed using SEM, FTIR and SIMS techniques. Increasing TEOS flow or decreasing O2 flow increased the deposition rate and the compressive stress of the oxide film but produced a less denser film. The deposition rate decreased owing to the decrease in the sticking coefficient of the TEOS and the O2 molecules onto the substrate Si with increasing the substrate temperature. Increasing the substrate temperature produced a denser film with a lower etch rate and the higher refractive index by lowering SiOH and moisture contents. Increasing the rf power increases the ion bombardment energy. This increase in energy, in turn, increases the deposition rate and tends to make the film denser. No appreciable changes were found in the deposition rate but the refractive index and the stress of the film decreased with increasing the deposition pressure. The carbon content in the plasma TEOS CVD oxide film prepared under our standard deposition conditions were very low according to the SIMS analysis results.

• Bulletin of the Korean Chemical Society
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• 제32권10호
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• pp.3571-3574
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• 2011

Nano-scaled metal oxides have been attractive materials for sensors, photocatalysis, and dye-sensitization for solar cells. We report the controlled synthesis and characterization of single crystalline $TiO_2$ nanowires via a catalyst-assisted vapor-liquid-solid (VLS) and vapor-solid (VS) growth mechanism during TiO powder evaporation. Scanning electron microscope (SEM) and transmission electron microscope (TEM) studies show that as grown $TiO_2$ materials are one-dimensional (1D) nano-structures with a single crystalline rutile phase. Also, energy-dispersive X-ray (EDX) spectroscopy indicates the presence of both Ti and O with a Ti/O atomic ratio of 1 to 2. Various morphologies of single crystalline $TiO_2$ nano-structures are realized by controlling the growth temperature and flow rate of carrier gas. Large amount of reactant evaporated at high temperature and high flow rate is crucial to the morphology change of $TiO_2$ nanowire.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.358-361
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• 1999

This paper describes on the fabrication and characteristics of hot-film type micro-flowsensors integrated with Pt-RTD\`s and micro-heater on the Si substrate, in which MgO thin-films were used as medium layer in order to improve adhesion of Pt thin-films to SiO$_2$ layer The MgO layer improved adhesion of Pt thin-films to SiO$_2$` layer without any chemical reactions to Pt thin-films under high as gas flow rate and its conductivity increased due to increase of heat-loss from sensor to external. Output voltage was 82 mV at N2 flow rate of 2000 sccm/min, heating power of 1.2W. The respons time was about 100 msec when input flow was step-input

• 한국재료학회지
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• 제17권2호
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• pp.61-67
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• 2007

The magnetron reactive sputtering was adopted to deposit CuO buffer layers on the polyimide surfaces for increasing the adhesion strength between Cu thin films and polyimide, varying $O_2$ gas flow rate from 1 to 5 sccm. The CuO oxide was formed through all the $O_2$ gas flow rates of 1 to 5 sccm, showing the highest value at the 3 sccm $O_2$ gas flow rate. The XPS analysis revealed that the $Cu_2O$ oxide was also formed with a significant ratio during the reactive sputtering. The adhesion strength is mainly dependent on the amount of CuO in the buffer layers, which can react with C-O-C or C-N bonds on the polyimide surfaces. The adhesion strength of the multi-layered Cu/buffer layer/polyimide specimen decreased linearly as the heating temperature increased to $300^{\circ}C$, even though there showd no significant change in the chemical state at the polyimide interface. This result is attributed to the decrease in surface roughness of deposited copper oxide on the polyimide, when it is heated.

• 한국표면공학회지
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• 제35권2호
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• pp.113-121
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• 2002

We have investigated insulating properties of $SiO_2$ interlayer for the thin film strain gauge, which were prepared by RF magnetron sputtering method in various deposition conditions, such as Ar pressure, gas flow rates and sputtering gases. SEM, AFM and FT-IR techniques were used to analyze its structures and composition. As the Ar pressure and the flow rate increased, the insulating interlayer showed low insulating resistance due to its porous structure and defects. Oxygen deficiency in $SiO_2$ was decreased as fabricated by hydrogen reactive sputtering. We could enhance the surface mobility of sputtered adatoms by using Ar/$H_2$ sputtering gas and obtain a good surface roughness and insulating property. The optimum insulating resistance of 9.22 G$\Omega$ was obtained in Ar/30% $H_2$ mixed gas, flow rate 10sccm, and 1mTorr.