• 공학논문집
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• 제3권1호
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• pp.189-197
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• 1998

생체적합성이 뛰어난 Hydroxyapatite(HAp)를 Wet Chemical Process로 만든 후 Ion Beam Assisted Deposition (IBAD)를 이용하여 Ti-6Al-4V의 표면에 coating 시켰다. 그런후 5ppm, 10ppm, 20ppm, 100ppm의 $AgNO_3$용액으로 HAp의 Ca이온과 Ag이온을 치환시켰다. 본 논문에서는 Ag-HAp로 coating된 Ti-6Al-4V를 만들어 항균효과와 생체적합성을 연구하였다. 먼저 생체 대체재료 이식수술시 감염이 큰 2가지 종류의 bacteria (P. Aeruginosa, S. Epidermidis)로 항균 test를 하였고, 그 결과 20ppm의 $AgNO_3$로 처리한 Ti-6Al-4V에서 우수한 항균성이 관찰되었다. 또한 생체적합성 연구을 위해 osteoblast와 macrophages로 생체적합성 실험을 하여 SEM으로 관찰한 결과, 5ppm과 10ppm의 $AgNO_3$로 처리한 Ti-6Al-4V 에서 좋은 생체적합성을 보였다. HAp의 Ca 이온에 치환된 Ag 이온의 항균원리를 관찰하기 위하여, 가장 일반적인 bacteria인 E. coli를 Ag-HAp로 처리한 후 transmission electron microscope (TEM)으로 관찰하였다. Ag-HAp로 처리한 E. coli에서 cell wall과 cytoplasm이 파괴된 것이 관찰되었고, cytoplasm에서는 검은점이 발견되었다. 이 검은점을 Energy dispersive analysis X-ray (EDAX)로 분석한 결과 미량의 Ag이온이 검출되었다. 이로써 Ag 이온이 효과적으로 Bacteria를 파괴하여 항균효과를 나타내는 것을 알 수 있었다.

• 한국자기학회지
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• 제14권2호
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• pp.59-64
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• 2004

나노 결정립 구조를 갖는 Fe-Al-O 연자성 산화막을 이온빔 에칭법으로 에칭하면서 연자기적 특성의 변화를 조사하였다. 두께가 감소할수록 보자력과 각형비가 증가하고 AFM 으로 조사한 표면굴곡도 증가하는 것으로 보아 결정립의 크기가 증가하는 것으로 판단된다. 이러한 현상은 비정질을 열처리한 나노결정립 연자성 재료와 다르게 성막하는 과정의 온도 상승에 의한 결정성장이 원인으로 판단된다. 따라서 우수한 연자성 박막을 제조하기 위해서는 두께 및 성막시간 등 최적 제조조건을 찾아야 한다. 마그네트론 스퍼터링법으로 제조된 Fe-Al-O 산화막의 경우 900 nm 이상에서 보자력이 1 Oe 이하인 연자성 박막을 얻을 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.297-297
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• 2008

Buffer layers play an important role in the development of high critical current density coated conductor. $LaMnO_3$, $SrTiO_3$ and $BaZrO_3$ buffer layers were compatible with MgO surfaces and also provide a good template for growing high current density REBCO(RE=Rare earth) films. Systematic studies on the influences of pulsed laser deposition parameters (deposition temperature, deposition pressure, processing gas, laser energy density, etc.) on microstructure and texture properties of $LaMnO_3$, $SrTiO_3$ and $BaZrO_3$ films as buffer layer deposited on ion-beam assisted deposition MgO (IBAD_MgO) template by pulse laser deposition method, were carried out. These results will be presented together with the discussion on the possible use of this material in HTS coated conductor as buffer.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.100-101
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• 2012

The plasma damage free and room temperature processedthin film deposition technology is essential for realization of various next generation organic microelectronic devices such as flexible AMOLED display, flexible OLED lighting, and organic photovoltaic cells because characteristics of fragile organic materials in the plasma process and low glass transition temperatures (Tg) of polymer substrate. In case of directly deposition of metal oxide thin films (including transparent conductive oxide (TCO) and amorphous oxide semiconductor (AOS)) on the organic layers, plasma damages against to the organic materials is fatal. This damage is believed to be originated mainly from high energy energetic particles during the sputtering process such as negative oxygen ions, reflected neutrals by reflection of plasma background gas at the target surface, sputtered atoms, bulk plasma ions, and secondary electrons. To solve this problem, we developed the NBAS (Neutral Beam Assisted Sputtering) process as a plasma damage free and room temperature processed sputtering technology. As a result, electro-optical properties of NBAS processed ITO thin film showed resistivity of $4.0{\times}10^{-4}{\Omega}{\cdot}m$ and high transmittance (>90% at 550 nm) with nano- crystalline structure at room temperature process. Furthermore, in the experiment result of directly deposition of TCO top anode on the inverted structure OLED cell, it is verified that NBAS TCO deposition process does not damages to the underlying organic layers. In case of deposition of transparent conductive oxide (TCO) thin film on the plastic polymer substrate, the room temperature processed sputtering coating of high quality TCO thin film is required. During the sputtering process with higher density plasma, the energetic particles contribute self supplying of activation & crystallization energy without any additional heating and post-annealing and forminga high quality TCO thin film. However, negative oxygen ions which generated from sputteringtarget surface by electron attachment are accelerated to high energy by induced cathode self-bias. Thus the high energy negative oxygen ions can lead to critical physical bombardment damages to forming oxide thin film and this effect does not recover in room temperature process without post thermal annealing. To salve the inherent limitation of plasma sputtering, we have been developed the Magnetic Field Shielded Sputtering (MFSS) process as the high quality oxide thin film deposition process at room temperature. The MFSS process is effectively eliminate or suppress the negative oxygen ions bombardment damage by the plasma limiter which composed permanent magnet array. As a result, electro-optical properties of MFSS processed ITO thin film (resistivity $3.9{\times}10^{-4}{\Omega}{\cdot}cm$, transmittance 95% at 550 nm) have approachedthose of a high temperature DC magnetron sputtering (DMS) ITO thin film were. Also, AOS (a-IGZO) TFTs fabricated by MFSS process without higher temperature post annealing showed very comparable electrical performance with those by DMS process with $400^{\circ}C$ post annealing. They are important to note that the bombardment of a negative oxygen ion which is accelerated by dc self-bias during rf sputtering could degrade the electrical performance of ITO electrodes and a-IGZO TFTs. Finally, we found that reduction of damage from the high energy negative oxygen ions bombardment drives improvement of crystalline structure in the ITO thin film and suppression of the sub-gab states in a-IGZO semiconductor thin film. For realization of organic flexible electronic devices based on plastic substrates, gas barrier coatings are required to prevent the permeation of water and oxygen because organic materials are highly susceptible to water and oxygen. In particular, high efficiency flexible AMOLEDs needs an extremely low water vapor transition rate (WVTR) of $1{\times}10^{-6}gm^{-2}day^{-1}$. The key factor in high quality inorganic gas barrier formation for achieving the very low WVTR required (under ${\sim}10^{-6}gm^{-2}day^{-1}$) is the suppression of nano-sized defect sites and gas diffusion pathways among the grain boundaries. For formation of high quality single inorganic gas barrier layer, we developed high density nano-structured Al2O3 single gas barrier layer usinga NBAS process. The NBAS process can continuously change crystalline structures from an amorphous phase to a nano- crystalline phase with various grain sizes in a single inorganic thin film. As a result, the water vapor transmission rates (WVTR) of the NBAS processed $Al_2O_3$ gas barrier film have improved order of magnitude compared with that of conventional $Al_2O_3$ layers made by the RF magnetron sputteringprocess under the same sputtering conditions; the WVTR of the NBAS processed $Al_2O_3$ gas barrier film was about $5{\times}10^{-6}g/m^2/day$ by just single layer.