• Proceedings of the Membrane Society of Korea Conference
• /
• 2004.05a
• /
• pp.74-77
• /
• 2004

Porous membranes were prepared via thermally induced phase separation (TIPS) of (ethylene-co-vinyl alcohol) (EVOH)/glycerol mixtures. The liquid-liquid (L-L) phase boundaries are shifted to higher temperature when the ethylene contents in EVOH increase. Moreover, the kinetic study proved that the growth of droplets formed by the general liquid-liquid (L-L) phase separation obeyed a power-law scaling relationship in the later stage of spinodal decomposition (SD). A new phase separation mechanism was presented, in which the L-L phase separation could be resulted from the crystallization. The hollow fiber membranes were prepared. The membranes showed asymmetric structures with skin layer near the outer surface, the larger pores just below the skin layer and the smaller pores near the inner surface. The effect of ethylene content (EC) in EVOH, cooling water bath temperature and take-up speed on membrane performance was investigated.

• Electrical & Electronic Materials
• /
• v.19 no.9
• /
• pp.11-19
• /
• 2006

SLS crystallization and CMOS LTPS process have been developed for high performance and uniform characteristics. By strictly optimizing SLS optics in conventional 2 shot SLS process, threshold voltage variation of 720 pixel TFTs in 2.2-inch QVGA panel (240xRGB) was remarkably decreased from 1.89 V to 0.56 V of 3sigma value. Mobility of the channel doped NTFT and PTFT for circuits were $146\;and\;38cm^{2}/Vs$, respectively. Functional unit circuits for SOG were also fabricated and properly operated.

• Bulletin of the Korean Chemical Society
• /
• v.18 no.12
• /
• pp.1249-1256
• /
• 1997

Single phase La1-xSrxCoO3 (x≤0.2) was synthesized as a uniform sized 100 nm particulates with relatively high surface area of 20-30 m2/g, at low temperature (≥600 ℃), from a polymeric gel precursors prepared by using poly(vinyl alcohol) as homogenizer. No minor phase developed during the crystallization when polymer/metal mole ratio was higher than 3. As the polymer/metal mole ratio was raised in the gel, the amount of carbonaceous residues in the amorphous solid precursor prepared by heating the gel at 300 ℃ increased. Most of the residues were eliminated by exothermic thermal decomposition around 400 ℃. The amount of residual carbon (less than 1%) left in the crystalline La1-xSrxCoO3 decreased as more polymer was used, eliminating detrimental effect which might be posed by using large amount of organic homogenizer. The crystal structure of La1-xSrxCoO3 synthesized at temperature lower than 800 ℃ was observed to be shifted from rhombohedral to more symmetric cubic. The structure shifted back to rhombohedral as the cubic sample was annealed at 1000 ℃.

• Journal of the Semiconductor & Display Technology
• /
• v.20 no.4
• /
• pp.1-5
• /
• 2021

Field-effect transistors based on solution-processed metal oxide semiconductors has attracted huge attention due to their intrinsic characteristics of optical and electrical characteristics with benefits of simple and low-cost process. Especially, spray-pyrolysis has shown excellent device performance which compatible to vacuum-processed Field-effect transistors. However, the high annealing temperature for crystallization of MOS and narrow range of precursors has impeded the progress of the technology. Here, we demonstrated the nc-ZnO/ZnO films performed by spray-pyrolysis with incorporating ZnO nanoparticles into typical ZnO precursor. The films exhibit preserving morphological properties of poly-crystalline ZnO and enhanced electrical characteristics with potential for low-temperature processability. The influence of nanoparticles within the film was also researched for realizing ZnO films providing good quality of performance.

• Applied Chemistry for Engineering
• /
• v.19 no.5
• /
• pp.497-503
• /
• 2008

A variety of techniques has been employed in order to reduce problems caused by the crystallization of paraffin and saturated fatty acid esters in diesel fuel containing biodiesels. Methacrylate copolymers are known as additives which reduce the pour point and cold filtering plugging point (CFPP) of diesel fuels. This paper describes the synthesis, characterization and low temperature properties, having as an initial step the synthesis of the alkyl methacrylate monomers by esterification of methacrylic acid with C12, C18, and C22 fatty alcohols. The copolymerization of these monomers with styrene was then performed, with molar ratios of 30:70, 50:50 and 70:30 for styrene:alkyl methacrylate. All copolymers were characterized by $^1H-NMR$, FT-IR, and gel permeation chromatography (GPC). The poly(styrene-co-alkyl methacrylate)s (PStmSMAn) leads to a large reduction in the pour point and CFPP of poly(styrene-co-alkyl methacrylate) in ultra low sulfur diesel (ULSD) and BD5 with treated 100~5000 ppm of poly(styrene-co-alkyl methacrylate). BD5 fuel containing 5000 ppm of the copolymer (PSt82SMA18) showed a $25^{\circ}C$ and $9^{\circ}C$ reduction in their pour points and CFPP, respectively.

• Current Photovoltaic Research
• /
• v.2 no.1
• /
• pp.1-7
• /
• 2014

We developed a method of growing thin Si film at $600^{\circ}C$ by hot wire CVD using a very thin large-grained poly-Si seed layer for thin-film Si solar cells. The seed layer was prepared by crystallizing an amorphous Si film by vapor-induced crystallization using $AlCl_3$ vapor. The average grain size of the p-type epitaxial Si layer was about $20{\mu}m$ and crystallographic defects in the epitaxial layer were mainly low-angle grain boundaries and coincident-site lattice boundaries, which are special boundaries with less electrical activity. Moreover, with a decreasing in-situ boron doping time, the mis-orientation angle between grain boundaries and in-grain defects in epitaxial Si decreased. Due to fewer defects, the epitaxial Si film was high quality evidenced from Raman and TEM analysis. The highest mobility of $360cm^2/V{\cdot}s$ was achieved by decreasing the in-situ boron doping time. The performance of our preliminary thin-film solar cells with a single-side HIT structure and $CoSi_2$ back contact was poor. However, the result showed that the epitaxial Si film has considerable potential for improved performance with a reduced boron doping concentration.

• Membrane Journal
• /
• v.26 no.6
• /
• pp.449-457
• /
• 2016

In this study, polyvinylidene fluoride (PVDF) membrane with excellent mechanical properties and chemical resistance was prepared and characterized for the application of water treatment. Dibutyl-phthalate (DBP) was used as a diluent for making a membranes through temperature induced phase separation (TIPS) method, and the crystallization temperature, melting point, cloud point and SEM image were observed with different ratio of diluent in polymer/diluent mixture. The crystallization temperature and melting point increased proportionally with the content of polymer, while the cloud point temperature decreased. Finally, it was confirmed that stable membrane could be manufactured at a polymer content of 62 wt% and a temperature $125^{\circ}C$ using the phase diagram of PVDF/DBP mixtures with temperatures.

• Journal of Information Display
• /
• v.10 no.1
• /
• pp.33-36
• /
• 2009

A new hybrid silicon thin-film transistor (TFT) fabrication process using the DPSS laser crystallization technique was developed in this study to realize low-temperature poly-Si (LTPS) and a-Si:H TFTs on the same substrate as a backplane of the active-matrix liquid crystal flat-panel display (AMLCD). LTPS TFTs were integrated into the peripheral area of the activematrix LCD panel for the gate driver circuit, and a-Si:H TFTs were used as a switching device of the pixel electrode in the active area. The technology was developed based on the current a-Si:H TFT fabrication process in the bottom-gate, back-channel etch-type configuration. The ion-doping and activation processes, which are required in the conventional LTPS technology, were thus not introduced, and the field effect mobility values of $4\sim5cm^2/V{\cdot}s$ and $0.5cm^2/V{\cdot}s$ for the LTPS and a-Si:H TFTs, respectively, were obtained. The application of this technology was demonstrated on the 14.1" WXGA+(1440$\times$900) AMLCD panel, and a smaller area, lower power consumption, higher reliability, and lower photosensitivity were realized in the gate driver circuit that was fabricated in this process compared with the a-Si:H TFT gate driver integration circuit

• Membrane Journal
• /
• v.27 no.5
• /
• pp.458-467
• /
• 2017

In this study, we prepared PVDF membranes via TIPS for water treatment applications. PVDF was used for its excellent chemical and mechanical properties. The effect of coagulation bath composition, temperature, and heat capacity on the overall membrane morphology was studied and observed using SEM. A mixture of DOP and DBP was used as the diluent, and silica was used as an additive. It was observed that as the heat capacity of the coagulation bath increased, the crystallization rate of PVDF decreased yielding larger pores. Also, as the heat capacity of the coagulation bath decreased, the crystallization rate of PVDF increased yielding smaller pores.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.08a
• /
• pp.286-286
• /
• 2011

최근 폴리머를 기판으로 하는 Flexible TFT (thin film transistor)나 3D-ULSI (three dimensional ultra large-scale integrated circuit)에서 높은 에너지 소비효율과, 빠른 반응 속도를 실현 시키기 위해 낮은 비저항(resistivity)을 가지며, 높은 홀 속도(carrier hall mobility)를 가지는 다결정 반도체 박막(poly-crystalline thin film)을 만들고자 하고 있다. 이를 실현 시키기 위해서는 높은 온도에서 장시간의 열처리가 필요하며, 이는 폴리머 기판의 문제점을 야기시킬 뿐 아니라 공정시간이 길다는 단점이 있었다. 이에 반도체 박막의 재결정화 온도를 낮춰주는 metal (Al, Ni, Co, Cu, Ag, Pd etc.,)을 이용하여 결정화 시키는 방법이 많이 연구 되어지고 있지만, 이 또한 재결정화가 이루어진 반도체 박막 안에 잔여 금속(residual metal)이 존재하게 되어 비저항을 높이고, 홀 속도를 감소시키는 단점이 있다. 이에 본 실험은 HiPIMS (High power impulse magnetron sputtering)와 PIII and D (plasma immersion ion implantation and deposition) 공정을 복합시킨 프로세스로 적은양의 금속이온주입을 통하여 재결정화 온도를 낮췄을 뿐 아니라, 잔여 하는 금속의 양도 매우 적은 다결정 반도체 박막을 만들 수 있었다. 분석 장비로는 박막의 결정화도를 측정하기 위해 GAXRD (glancing angle X-ray diffractometer)를 사용하였고, 잔여 하는 금속의 양과 화학적 결합 상태를 알아보기 위해 XPS를 통해 분석을 하였다. 마지막으로 홀 속도와 비저항을 측정하기 위해 Hall measurement와 Four-point prove를 사용하였다.