• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1108-1109
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• 2008

To survive in outdoor environments, photovoltaic modules rely on packaging materials to provide requisite durability. We analyzed the properties of encapsulant materials that are important for photovoltaic module packaging. Recently, the thickness of solar cell gets thinner to reduce the quantity of silicon. And the reduced thickness make it easy to be broken while PV module fabrication process. Solar cell's micro cracks are increasing the breakage risk over the whole value chain from the wafer to the finished module, because the wafer or cell is exposed to tensile stress during handling and processing. This phenomenon might make PV module's maximum power and durability down. So, when using thin solar cell for PV module fabrication, it is needed to optimize the material and fabrication condition which is quite different from normal thick solar cell process. Normally, gel-content of EVA sheet should be higher than 80% so PV module has long term durability. But high gel-content characteristic might cause micro-crack on solar cell. In this experiment, we fabricated several specimen by varying curing temperature and time condition. And from the gel-content measurement, we figure the best fabrication condition. Also we examine the crack generation phenomenon during experiment.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.299-303
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• 1991

A lamp heated LPCVD equipment has been made. Wafer is heated by an array of fifteen tungsten halogen lamps above the front side of a wafer and pyrometer views the back side of the wafer through $CaF_2$ window. Reactor which consisits of a quartz window and a water cooled-stainless steel plate can be evacuated to $5{\times}10^{-3}$ torr with a rotary vane pump. By pyrolysis of $SiH_4$ at about $600^{\circ}C$, polysilicon has been formed on the silicon dioxide film. The measured results show that thickness nonuniformity is 15% and temperature nonuniformity is 1.1%. Because activation energy of pyrolysis of $SiH_4$ is very high, about 1.8eV, small temperature variation will induce large thickness nonuniformity. The main cause of temperature nonuniformity is unsymmetry of lamp power and an unbalanced cooling structure. Charls & Evans' SIMS result shows that the oxygen content in the deposited polysilicon is comparable to that of silicon substrate but carbon content is ten times higher.

• Korean Journal of Crystallography
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• v.6 no.2
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• pp.111-117
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• 1995

TiO2 thin films were prepared on a (100)silicon wafer using a chemical vapor deposition(CVD) method. The deposition experiments were performed using the TTIP in the deposition temperature ransing from 200 content. The deposition rate of TiO2 was increased with the substrate temperature and the oxygen content. The thickness of the deposited thin film and the compositional analysis of this thin films with theoxygen content were measured using Ellipsometry, SEM and ESCA, respectively. The deposited thin film was composed of a bilayer, external TiO2 and internal Ti. Carbon as a residual impurity was found to remain when zero sccm O2 was purged into a reaction chamber and the composition of the deposited thin film was found to change Ti into TiO in a deeper layer. However, when 600sccm O2 was supplied to a reaction chamber, it has been found to reside less carbon content than without O2. Finally, in the condition of 1200sccm O2, no impurity level of carbon was observed and a deeper layer consisted of the Ti composite, even though the deposited surface was composed of TiO2.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.2
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• pp.319-324
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• 2014

The wafer carrier is made of PP, PC, PE resin which have excellent heat and chemical resistance and electrical properties. However, particle generation has become a problem due to static electricity generated in the carrier. Some conductive material such as carbon black (CB) and carbon fiber (CF) are added for the purpose of anti-static, however, additional for motility and particle contamination problems due to high carbon content occurs. In this paper, the electrical characteristics and workability are observed and compared by adding low Carbon Nono Tube(CNT) to each PP, PC and PE resin to solve the problem.

• ETRI Journal
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• v.31 no.6
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• pp.675-679
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• 2009

$Ti_xSi_{1-x}O_y$ (TSO) thin films are fabricated using plasma-enhanced atomic layer deposition. The Ti content in the TSO films is controlled by adjusting the sub-cycle ratio of $TiO_2$ and $SiO_2$. The refractive indices of $SiO_2$ and $TiO_2$ are 1.4 and 2.4, respectively. Hence, tailoring of the refractivity indices from 1.4 to 2.4 is feasible. The controllability of the refractive index and film thickness enables application of an antireflection coating layer to TSO films for use as a thin film solar cell. The TSO coating layer on an Si wafer dramatically reduces reflectivity compared to a bare Si wafer. In the measurement of the current-voltage characteristics, a nonlinear coefficient of 13.6 is obtained in the TSO films.

• Polymer(Korea)
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• v.25 no.6
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• pp.884-892
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• 2001

Biodegradable wafers were prepared with poly (L-lactide-co-glycolide) (50 : 50 mole ratio of lactide to glycolide, molecular weight:5000 g/mole) by direct compression method for the sustained release of nifedipine to investigate the possibility of the treatment of hypertension. PLGA wafers were prepared by altering initial drug/polymer loading ratio, wafer thickness, and hydroxypropyl methylcellulose (HPMC) content. These wafers showed new zero-order release patterns for 11 days, and various biphasic release patterns could be obtained by altering the composition of wafers such as addition of matrix binder as HPMC to the PLGA wafer to reduce release rate of initial phase. The onset of polymer mass loss only occured after 4 days and about 40% of mass loss was observed after 11 days nifedipine release. This system had advantages in terms of simplicity in design and obviousness of drug release rate and may be useful as an implantable dosage form.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.2
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• pp.85-90
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• 2014

Ag paste has been used in the front electrode of the Si-solar cell. It is composed by Ag powder, glass frit, binder, solvent and dispersant. The role of the binder and the solvent is to make a flow and a printing property. However, it was not enough to report the printing properties with the variation of binder in the controled viscosity. In this study, we selected 3 kinds of typical binder which were used as binder for the paste in the industry, such as Ethyl cellulose, Hydroxypropyl cellulose and Acrylic. Ag pastes using these were prepared, controled viscosity and printed on the SiNx coated Si wafer. In the 'A paste' used Acrylic binder, printed hight was highest and 'H paste' used Hydroxypropyl cellulose binder was lowest. Because 'H paste' was high viscosity due to the molecular weight, the solvent was added in the paste to control the viscosity. Therefore, the content of solid was lower in 'H paste'. The relative pattern width which is related to the spreading of paste was the best in the case of 'H paste' and 'EH paste' at $30^{\circ}C$. It is thought that the optimization of the relative pattern width is possible for a paste by the controling shear thinning phenomenon. In the case of 'A paste', though printing hight was best, the pattern width was dependant on the temperature.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.61.2-61.2
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• 2010

Ag thick-film has usually been used for the front electrode of Si solar cells with the outstanding electrical properties. Ag paste consists of Ag powers, vehicles, frits and additives. Ag paste has broadly been screen-printed on the front side of Si wafer with the merits of low cost and simplicity. The optimal contact formation between Ag electrodes and Si wafer in the front electrode during a fast firing has been considered as the key factor for high efficiency. Although the content of frit in Ag pastes is less than 5wt%, it can profoundly influence the contact formation between Ag and Si under the fast firing. In this study, the effects of lead-free frits on the contacts between Ag and Si were studied with the thermal properties and compositions of various frits. Our experimental results showed that the electrical properties of cells were related to the interface structures between Ag and Si. It was found that current path of electrons from Si to Ag would be possible through the tunneling mechanism assisted by tens of nano-Ag recrystals on $n^+$ emitter as well as Ag recrystals penetrated into $n^+$ emitter layers. These preliminary studies will be helpful for designing the proper frits for the Ag pastes with considering the properties of various Si wafers.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.369.2-369.2
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• 2014

Diamond-like Carbon(DLC) films doping Si were deposited by linear ion source(LIS)-physical vapor deposition method on Si wafer. We have studied the effects of Si content on friction and wear properties of DLC films and the characteristics of the films were investigated using Nano-indentation, Micro raman spectroscopy, Field Emission-Scanning Electron Microscope (FM-SEM) and X-ray Photoelectron Spectroscopy (XPS). The films has been various low-friction and low-stress by varying the flow rates of silane gas. Under the about 2% of Si doping is very suitable for improving the adhesion of films and reducing internal stress while maintaining the surfaces hardness of DLC films. Linear ion source (LIS)를 사용하여 Si wafer위에 Si 이온이 첨가된 DLC 박막을 증착하였다. 참가된Si 이온의 양에 따라 DLC 박막에 미치는 영향을 분석하기 위하여 마찰 계수 및 경도를 비교하였고, Micro raman spectroscopy, Field Emission-Scanning Electron Microscope (FM-SEM) and X-ray Photoelectron Spectroscopy (XPS)를 통하여 표면 상태를 분석하였다. 천체 주입된 가스량의 약 2%까지 Si 이온 주입이 늘어날수록 DLC 박막의 마찰계수는 낮아졌고, 경도는 Si 이온이 주입되지 않았을 경우와 비슷한 값(약 20~23 GPa)을 가졌다. 2% 이상의 주입량에서는 마찰계수는 주입량이 늘어날수록 높아졌으며 경도는 떨어지는 경향을 보였다. 이는 Si이온이 2%이하로 첨가되었을 경우, DLC 박막의 생성시 탄소 이온들의 결합 Stress를 줄여 마찰계수가 줄어든다고 볼 수 있으며, 그 양이 2%이상이 되면 오히려 불순물로 작용하여 DLC 박막의 Stress는 급격히 증가하고 마찰계수도 높아짐을 알 수 있다.

• Proceedings of the KAIS Fall Conference
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• 2010.05a
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• pp.108-112
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• 2010

Confocal Imaging System is an essential machine for a wide range of inspection wafer. For concurrent and fast acquiring the image data of four channels, the new image acquisition system used the protocol of camera-link standard with the full mode of configuration in interconnection with a frame grabber integrated in a computer, which is popularly used for many cameras, so the programming environment of image processing is optional such as Visual C++, Matlab. In addition, many conventional methods were coordinately used for contribution to build the high quality of images for precise processing analog signals of PhotoMutiplier Tubes(PMTs), accurate control of scanning device, sensitivity of PMTs, and laser source. The prototype of new image acquisition system, could meet the goal of development, it is used in LSCM for high content screening to investigation the processes of elements of living specimens at the same time by simultaneous grab image data on 4 PMTs channels.