• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.222-222
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• 2010

Transparent semiconductor oxide thin films have been attracting considerable attention as potential channel layers in thin film transistors (TFTs) owing to their several advantageous electrical and optical characteristics such as high mobility, high stability, and transparency. TFTs with ZnO or similar metal oxide semiconductor thin films as the active layer have already been developed for use in active matrix organic light emitting diode (AMOLED). Of late, there have been several reports on TFTs fabricated with InZnO, AlZnSnO, InGaZnO, or other metal oxide semiconductor thin films as the active channel layer. These newly developed TFTs were expected to have better electrical characteristics than ZnO TFTs. In fact, results of these investigations have shown that TFTs with the new multi-component material have excellent electrical properties. In this work, we present TFTs with inverted coplanar geometry and with a novel HfInZnO active layer co-sputtered at room temperature. These TFTs are meant for use in low voltage, battery-operated mobile and flexible devices. Overall, the TFTs showed good performance: the low sub-threshold swing was low and the $I_{on/off}$ ratio was high.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.319.1-319.1
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• 2013

Solid oxide fuel cells (SOFCs) have been recognized as one of emerging renewable energy sources, due to minimized pollutant production and high efficiency in operation. The performance of SOFCs is largely dependent on the electrode polarization which involves the oxidation/reduction in cathodes and anodes along with the charge transport of ions and electronic carriers. Atomic layer deposition is based on the alternate chemical surface reaction occurring at low temperatures with high uniformity and superior step coverage. Such features can be extended into the coating of metal oxide and/or metal layer onto the porous materials. In particular, the atomic layer deposition is can manipulated in controlling the charge transport in terms of triple phase boundaries, in order to control artificially the electrochemical polarization in electrodes of SOFC. The current work applied atomic layer deposition of metal oxides intro the electrodes of SOFCs. The corresponding effect was monitored in terms of the electrochemical characterization. The roles of atomic layer deposition in solid oxide fuel cells are discussed towards optimized towards long-term durability at intermediate temperature.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.176.1-176.1
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• 2013

TCO (Transparent Conductive Oxide)는 투명 전도성 산화물 높은 투과율과 낮은 비저항 가지고 있어서 최근 사용된 평판디스플레이 LCD(liquid crystal display), PDP (Plasma Display Panel), OLED (Organic Light Emitting Display) 에 많이 사용되고 있다. 현재 양산화 되고 있는 ITO (Indium tin Oxide)는 좋은 전도율과 높은 투과율로서 가장 많이 쓰인다. 하지만 ITO중에 Indium Oxide는 치명적인 독성을 가지고 있으며 In의 저장량이 적어 시간이 갈수록 가격이 비싸지는 등 여러 가지 단점을 가지고 있다. 그것에 비해 AZO (aluminum-doped zinc oxide)는 독성이 없고 가격도 저렴하여 ITO의 단점을 보완 할 수 있는 물질이다. AZO 증착은 현재 sol-gel, CVD(chemical vapor deposition), Sputter, 등으로 사용되고 있으며 현재 많은 연구가 진행되고 있다. 본 실험에서는 PEN 기판을 사용하였으며, 플라즈마의 열적 데미지로 인한 기판의 변형 등 여러 가지 문제를 해결하기 위하여 박막의 열적 변형이 적고, 고밀도 플라즈마로 양질의 박막 증착이 가능한 FTS (Facing Target Sputtering)방법을 사용하여 AZO박막을 증착시키고 구조적, 전기적, 광학적인 특성을 평가 하였다. 측정 분석 결과 AZO는 가시광 영역에 높은 투과율이 요구되는 Flexible display 표시장치와 OLED, PDP, 유기태양전지 등 많은 영역에 사용이 가능 할 것이라 사료된다.

• Korean Journal of Materials Research
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• v.12 no.7
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• pp.533-539
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• 2002

Porous anodic aluminum oxide layer for nano templates was prepared in acidic solutions. In order to investigate effects of 2nd anodization on ordered formation behaviors of the porous oxide layers, electrochemical and microstructural studies were performed, primarily using TEM, FE- SEM, AFM, and Ultramicrotomy. The pore diameter of the anodic oxide layer increased approximately linearly with increasing voltages, and to the contrary, the pore density decreased. It was shown that 2nd anodizing on the cell base after dissolving 1st anodic oxide layer was remarkably effective for forming ordered array of the pores, comparing with the case for 1st anodization only. And for controlling the diameter of pores, widening method by chemical dissolution seemed more practical than by electrochemical methods.

• Journal of the Semiconductor & Display Technology
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• v.21 no.2
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• pp.74-84
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• 2022

As the semiconductor industry develops, the difficulty of newly required process technology becomes difficult, and the importance of production yield and product reliability increases. As an effort to minimize yield loss in the manufacturing process, interests in the process defect process for facility diagnosis and defect identification are continuously increasing. This research observed the plasma condition changes in the multi oxide/nitride layer deposition (MOLD) process, which is one of the 3D-NAND manufacturing processes through optical emission spectroscopy (OES) and monitored the result of whether the change in plasma characteristics generated in repeated deposition of oxide film and nitride film could directly affect the film. Based on these results, it was confirmed that if a change over a certain period occurs, a change in the plasma characteristics was detected. The change may affect the quality of oxide film, such as the film thickness as well as the interfacial surface roughness when the oxide and nitride thin film deposited by plasma enhenced chemical vapor deposition (PECVD) method.

• Korean Journal of Environmental Agriculture
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• v.12 no.2
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• pp.169-175
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• 1993

O-Ethyl S-methyl ethylphosphonothioate was studied for chemical and metabolic oxidation using $^{31}P-NMR$ analyses. The chemical shifts of O-ethyl ethylphosphonic acid (2) which is one of major metabolites were changed with the variation of oxidation systems. $^{31}P-NMR$ chemical shifts of 2 were observed at 40.15ppm from oxidaton by MCPBA, 30.98 ppm by MMPP, 29.31 ppm from in vitro rat liver microsomal oxidation, and 29.10 ppm from in vivo metabolism in houseflies. $^{31}P-NMR$ chemical shift of 2 in two different solvents such as deutero-chloroform and deuterium oxide were observed at 30.70 ppm and 40.15 ppm, respectively. And those of the metabolites were also observed at around 30 ppm under the conditions of pH 3, 5.6 and 14 and 47.91 ppm under pH 1 which is a strong acidic condition. It could be explained that the ionized form of 2 should have greater shielding effect on phosphorus atom and hence shows upfield chemical shift in polar solvents and alkaline conditions. On the other hand, a protonated form under organic solvents and the strong acidic condition should have less shielding effect than its ionized form, shifting the peak downfield.

• Journal of the Korean Applied Science and Technology
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• v.34 no.1
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• pp.50-57
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• 2017

Zinc oxide is, one of metal oxide semiconductor, harmless to human and environment-friendly. It has excellent chemical and thermal stability properties. Wurtzite-zinc oxide is a large band gap energy of 3.37 eV and high exciton binding energy of 60 meV. It can be applied to various fields, such as solar cells, degradation of the dye waste, the gas sensor. The photocatalytic activity of zinc oxide is varied according to the particle shape and change of crystallinity. Therefore, It is very important to specify the additives and the experimental variables. In this study, the zinc oxide were synthesized by using a microwave assisted hydrothermal synthesis. The precursor was used as the zinc nitrate, the pH value was controlled as 11 by NaOH. Surfactants are the ethanolamine, cetyltrimethylammonium bromide, sodium dodecyl sulfate, sorbitan monooleate was added by changing the concentration. The composite particles had the shape of a star-like, curcular cone, seed shape, flake-sphere. Physical and chemical properties of the obtained zinc oxide was characterized using x-ray diffractometer, field emission scanning electron microscopy, thermogravimetric analysis and optical properties was characterized using UV-visible spectroscopy, photoluminescence and raman spectroscopy.

• Journal of the Korean Chemical Society
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• v.35 no.6
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• pp.625-629
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• 1991

The electrical conductivity of the Niobium Oxide-Lead Oxide systems containing 2.5, 5.0, 7.5, and 10.0 mol% of Lead Oxide has been measured in a temperature range 700${\sim}$$1100^{\circ}C$ under oxygen partial pressure of 2.0 ${\times}$ $10^{-1}$${\sim}$1.0 ${\times}$ $10^{-5}$ atm. The electrical conductivities of the system decreased with increasing PbO mol% and varied from $10^{-5}$ to $10^{-1}$ $ohm^{-1}$ $cm^{-1}$. The activation energy for conductivity was about 1.70 eV. The oxygen pressure dependence of electrical conductivity revealed that the system was a mixed conductor between ionic and electronic conductivities at high oxygen pressures and a n-type electronic conductivity with oxygen pressure dependence of -1/4 order at low oxygen pressures. The defect structure and electrical conduction mechanism of the system have been discussed with the data obtained.

• Korean Journal of Materials Research
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• v.10 no.4
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• pp.282-289
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• 2000

$PbTiO_3$ films were fabricated by electron cyclotron resonance plasma enhanced chemical vapor deposition(ECR-PECVD). Deposition characteristics of $PbTiO_3$films on $RuO_2$ and Pt substrates were investigated with varying the flow rate of metalorganic source and substrate temperature. The residence time of Pb-oxide molecules in much longer on $RuO_2$ than on Pt substrate, while the perovskite nucleation is more difficult on $RuO_2$ than on Pt substrate. Therefore, the process conditions to obtain the single perovskite $PbTiO_3$ phase are more restricted on $RuO_2$ than on Pt substrates. An introduction of Ti-oxide seed layer increases perovskite nucleation density and thus enlarges the process window to obtain the single perovkite phase. The introduction of Ti-oxide seed layer make the PZT film that Ti-components of $PbTiO_3$ are partially substituted with Zr atoms have single perovskite phase for the wide range of Zr/(Zr+Ti) concentration ratios.

• Membrane and Water Treatment
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• v.7 no.6
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• pp.539-553
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• 2016

As a novel hydrophobic monomer, polytetrahydrofuran diacrylate (PTMGDA) was synthesized by the esterification reaction between polyethylene tetrahydrofuran (PTMG) and acryloyl chloride (AC). In situ free radical polymerization reaction method was utilized to fabricate poly (vinylidene fluoride) (PVDF)-PTMGDA-poly(ethylene oxide) dimethacrylate (PEGMA) ulrafiltration (UF) membranes. The performances of PVDF-PTMGDA-PEGMA UF membranes in terms of morphologies, mechanical properties, separation properties and hydrophilicities were investigated. The introduction of the PTMGDA-PEGMA dopants not only increased the membranes' pure water flux, but also improved their mechanical properties and the dynamic contact angles. The addition of the PTMGDA/PEGMA dopants led to the formation of the finger-like structure in the membrane bulk. With the increase concentration of PTMGDA/PEGMA dopants, the porosity and the mean effective pore size increased. Those performances were coincide with the physicochemical properties of the casting solutions.