• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.619-622
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• 2005

본 논문에서는 서로 다른 Si 두께 ($T_{Si}$ = 27, 50 nm) 를 갖는 SOI (Silicon On Insulator) 기판 위에 다양한 두께의 Ni/Co를 순차적으로 증착한 후 Bulk-Si과의 비교를 통해 Silicide의 형성 특성에 대하여 분석하였다. 우선 급속 열처리 (RTP, Rapid Thermal Processing) 를 통하여 Silicide를 형성한 후 측정결과 Si두께에 따라 Silicide의 특성이 달라짐을 확인하였다. 두꺼운 두께의 Si-film을 갖는 SOI 기판을 사용한 경우 증착된 금속의 두께에 따라 Bulk-Si와 비슷한 면저항 특성을 보였으나, 얇은 두께의 Si-film을 갖는 SOI기판을 사용한 경우에는 제한된 Si의 공급으로 인한 Silicide의 비저항 증가로 인하여 증착된 금속의 두께에 따라 면저항이 감소하다가 다시 증가하는 'V' 자형 곡선을 나타내었다.

• Korean Journal of Remote Sensing
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• v.32 no.4
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• pp.353-364
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• 2016

Yangon city is experienced a rapid urban expansion over the last two decades due to accelerate with the socioeconomic development. This research work studied an investigation into the application of the integration of the Remote Sensing (RS) and Geographic Information System (GIS) for observing Land Use and Land Cover (LULC) patterns and evaluate its impact on Land Surface Temperature (LST) of the downtown, suburban 1 and suburban 2 of Yangon city. The main purpose of this paper was to examine and analyze the variation of the spatial distribution property of the LULC of urban spatial information related with the LST and Normalized Difference Vegetation Index (NDVI) using RS and GIS. This paper was observed on image processing of LULC classification, LST and NDVI were extracted from Landsat 8 Operational Land Imager (OLI) image data. Then, LULC pattern was linked with the variation of LST data of the Yangon area for the further connection of the correlation between surface temperature and urban structure. As a result, NDVI values were used to examine the relation between thermal behavior and condition of land cover categories. The spatial distribution of LST has been found mixed pattern and higher LST was located with the scatter pattern, which was related to certain LULC types within downtown, suburban 1 and 2. The result of this paper, LST and NDVI analysis exhibited a strong negative correlation without water bodies for all three portions of Yangon area. The strongest coefficient correlation was found downtown area (-0.8707) and followed suburban 1 (-0.7526) and suburban 2(-0.6923).

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.86.2-86.2
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• 2015

Cu2ZnSn(S,Se)4 thin film solar cells have been fabricated using sputtered Cu/Sn/Zn metallic precursors on Mo coated sodalime glass substrate without using a toxic H2Se and H2S atmosphere. Cu/Sn/Zn metallic precursors with various thicknesses were prepared using DC magnetron sputtering process at room temperature. As-deposited metallic precursors were sulfo-selenized inside a graphite box containing S and Se pellets using rapid thermal processing furnace at various sulfur to selenium (S/Se) compositional ratio. Thin film solar cells were fabricated after sulfo-selenization process using a 65 nm CdS buffer, a 40 nm intrinsic ZnO, a 400 nm Al doped ZnO, and Al/Ni top metal contact. Effects of sulfur to selenium (S/Se) compositional ratio on the microstructure, crystallinity, electrical properties, and cell efficiencies have been studied using X-ray diffraction, Raman spectroscopy, field emission scanning electron microscope, I-V measurement system, solar simulator, quantum efficiency measurement system, and time resolved photoluminescence spectrometer. Our fabricated Cu2ZnSn(S,Se)4 thin film solar cell shows the best conversion efficiency of 9.24 % (Voc : 454.6 mV, Jsc : 32.14 mA/cm2, FF : 63.29 %, and active area : 0.433 cm2), which is the highest efficiency among Cu2ZnSn(S,Se)4 thin film solar cells prepared using sputter deposited metallic precursors and without using a toxic H2Se gas. Details about other experimental results will be discussed during the presentation.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.250-253
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• 2007

An evaporated Ti/Pd/Ag contact system is most widely used to make high-efficiency silicon solar cells, however, the system is not cost effective due to expensive materials and vacuum techniques. Commercial solar cells with screen-printed contacts formed by using Ag paste suffer from a low fill factor and a high shading loss because of high contact resistance and low aspect ratio. Low-cost Ni and Cu metal contacts have been formed by using electroless plating and electroplating techniques to replace the Ti/Pd/Ag and screen-printed Ag contacts. Ni/Cu alloy is plated on a silicon substrate by electro-deposition of the alloy from an acetate electrolyte solution, and nickel-silicide formation at the interface between the silicon and the nickel enhances stability and reduces the contact resistance. It was, therefore, found that nickel-silicide was suitable for high-efficiency solar cell applications. The Ni contact was formed on the front grid pattern by electroless plating followed by anneal ing at $380{\sim}400^{\circ}C$ for $15{\sim}30$ min at $N_{2}$ gas to allow formation of a nickel-silicide in a tube furnace or a rapid thermal processing(RTP) chamber because nickel is transformed to NiSi at $380{\sim}400^{\circ}C$. The Ni plating solution is composed of a mixture of $NiCl_{2}$ as a main nickel source. Cu was electroplated on the Ni layer by using a light induced plating method. The Cu electroplating solution was made up of a commercially available acid sulfate bath and additives to reduce the stress of the copper layer. The Ni/Cu contact was found to be well suited for high-efficiency solar cells and was successfully formed by using electroless plating and electroplating, which are more cost effective than vacuum evaporation. In this paper, we investigated low-cost Ni/Cu contact formation by electroless and electroplating for crystalline silicon solar cells.

• Current Photovoltaic Research
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• v.2 no.4
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• pp.177-181
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• 2014

$Cu_2ZnSn(S_xSe_{1-x})_4$ (CZTSSe) absorber thin films were prepared on Mo coated soda lime glass substrates by sulfo-selenization of sputtered stacked Zn-Sn-Cu precursor thin films. The Zn-Sn-Cu precursor thin films were sulfo-selenized inside a graphite box containing S and Se powder using rapid thermal processing furnace at $540^{\circ}C$ in Ar atmosphere with pre-treatment at $300^{\circ}C$. The effect of different S/Se ratio on the structural, compositional, morphological and electrical properties of the CZTSSe thin films were studied using XRD (X-ray diffraction), XRF (X-ray fluorescence analysis), FE-SEM (field-emission scanning electron microscopy), respectively. The XRD, FE-SEM, XRF results indicated that the properties of sulfo-selenized CZTSSe thin films were strongly related to the S/Se composition ratio. In particular, the CZTS thin film solar cells with S/(S+Se)=0.25 shows best conversion efficiency of 4.6% ($V_{oc}$ : 348 mV, $J_{sc}$ : $26.71mA/cm^2$, FF : 50%, and active area : $0.31cm^2$). Further detailed analysis and discussion for effect of S/Se composition ratio on the properties CZTSSe thin films will be discussed.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.10
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• pp.87-93
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• 1994

Ohmic contacts between Au and p-HgHg_{0.7}Cd_{0.3}Te$ with low specific contact resistance have been obtained. The contact region of the wafer is first pre-heated for 5 seconds in a rapid thermal processing equipment. The temperature reaches a maximum value of about 200$^{\circ}C$ at the end of the 5 seconds. Next, a thin Au film is formed on the contact region by immersing the sample in AuCl$_{3}$ solution. the sample is then post-annealed in the same condition as the pre-heating after Pb/In pad metals are deposited on the electroless Au contacts. The specific contact resistance measured by transmission line model is 5${\times}10^{-3}{\Omega}cm^{2}$ at 80K. RBS and differential Hall measurement data suggest that the above low resistance ohmic contact is ascribed to surface traps and increased gold diffusion rate.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.280-284
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• 2004

Multicrystalline silicon wafers were textured in an alkaline bath, basically using sodium hydroxide and in acidic bath, using mainly hydrofluoric acid (HF), nitric acid $(HNO_3)$ and de-ionized water (DIW). Some wafers were also acid polished for the comparative study. Comparison of average reflectance of the samples treated with the new recipe of acidic solution showed average diffuse reflectance less than even 5 percent in the optimized condition. Solar cells were thus fabricated with the samples following the main steps such as phosphorus doping for emitter layer formation, silicon nitride deposition for anti-reflection coating by plasma enhanced chemical vapor deposition (PECVD) and front surface passivation, screen printing metallization, co-firing in rapid thermal processing (RTP) Furnace and laser edge isolation and confirmed >14 % conversion efficiency from the best textured samples. This isotropic texturing approach can be instrumental to achieve high efficiency in mass production using relatively low cost silicon wafers as starting material.

• The Korean Journal of Food And Nutrition
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• v.31 no.4
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• pp.511-519
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• 2018

The baking properties of rice bread with different percentages of butter and oil in wet and dry rice flour were investigated. The moisture, damaged starch, mean diameter, pasting properties by amylogram and RVA (Rapid Visco Analyzer), as well as thermal properties by DSC (Differential Scanning Calorimetry) of wet and dry rice flour were analyzed. The specific gravity and color (L, a, b) of the dough, as well as the appearance, color (L, a, b) and texture of the rice bread with different percentages of butter and oil in wet and dry rice flour were also analyzed. As a result, the wet rice flour were composed of a noted higher content in moisture, compared to the dry rice flour (p<0.001). The wet rice flour had lower values of damaged starch, higher values of mean diameter and a higher peak viscosity than was noted in the dry rice flour (p<0.001). The wet rice flour showed a higher degree of hydration and gelatinization than was seen in the dry rice flour (p<0.001). The prevailing principle to utilize the replacement of wet rice flour with oil had a significant effect on the volume, specific volume and hardness of the rice bread (p<0.001). The hardness of the rice bread also showed a decreasing trend as the amount of the added oil was increased into the mixture. These results suggest that the replacement of wet rice flour with 5.8% oil is effective for the production of rice bread.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.3
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• pp.211-218
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• 2000

$PbZrO_3$precursor was prepared for the spin coating on the Pt/Ti/$SiO_2$/Si substrate. Two different heat treatment methods were used and the differencies were studied. One of the method is that the films were inserted into the furnace for 30 minutes and the other is that the films were annealed by rapid thermal annealing (RTA) for 1 minute at the same temperatures. We also examined the tendency of crystallization by annealing at the fixed temperature, $700^{\circ}C$ as a function of time, namely during 1, 10, 20, and 30 minitues, respectively. The optimum conditions for the crystallization of these films were at $550^{\circ}C$ during 30 min. and at $700^{\circ}C$ during 10 min. in muffle furnace and at $650^{\circ}C$ during 1 min in RTA furnace. The best condition for making good quality grains needs 30 min. at $700^{\circ}C$.

• Korean Journal of Food Science and Technology
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• v.47 no.4
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• pp.474-479
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• 2015

In this study, five different Gochujang (a traditional Korean sauce prepared using fermented red pepper paste) sauces were heated at $100^{\circ}C$ for 5 min using a continuous ohmic heating system. Ohmic heating yielded greater reduction in microbial counts (90-95% reduction) than did conventional heating (65-75% reduction). The sterilization effect of the continuous ohmic heater increased with increasing sample flow rate and decreasing Reynolds number inside the pipe. Low-viscosity samples had higher electrical conductivity and were better suited for ohmic heating than were high-viscosity samples. The color and texture were also satisfactorily maintained after ohmic heating. Compared with conventional heating, ohmic heating provided rapid and uniform heating, which is more suitable for aseptic thermal processing of viscous foods.