• 한국항행학회논문지
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• 제14권3호
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• pp.426-431
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• 2010

태양전지용 웨이퍼 제조공정에 있어 Slurry의 가격 비중은 약 68% 정도로 매우 큰 비중을 차지하고 있기 때문에, 제조비용 절감측면과 Wafering 원가혁신 및 산업폐기물 처리비용 절감효과, 환경오염 방지를 위해 Slurry의 순환 사용은 필수적이다. 기존 Slurry를 재생하는 방식은 물리적인 원심분리(데칸터) 방식을 이용한 방법을 사용하고 있으나 미분(微粉)이 남아 있어 재생품질에 한계가 있고, 대부분 액체, 100% 오일과 분리되지 않은 상태로 재생된다. 이 상태를 건조시키는 경우도 순도가 많이 떨어진다. 본 논문에서는 원심분리(데칸터) 방식과 케미컬 방식을 함께 사용하여, 태양전지 Wafering 공정에서 필수적인 Slurry를 재생함에 있어, 원심분리에 의한 재생품질의 한계를 극복할 수 있는 재생기술을 개발하였고, Slurry 재생에 대한 Total Solution을 제공하여 성능을 향상시키고 재생 회수율을 높였다.

• 한국재료학회지
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• 제25권9호
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• pp.487-491
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• 2015

In photovoltaic power generation where minority carrier generation via light absorption is competing against minority carrier recombination, the substrate thickness and material quality are interdependent, and appropriate combination of the two variables is important in obtaining the maximum output power generation. Medici, a two-dimensional semiconductor device simulation tool, is used to investigate the interdependency in relation to the maximum power output in front-lit Si solar cells. Qualitatively, the results indicate that a high quality substrate must be thick and that a low quality substrate must be thin in order to achieve the maximum power generation in the respective materials. The dividing point is $70{\mu}m/5{\times}10^{-6}sec$. That is, for materials with a minority carrier recombination lifetime longer than $5{\times}10^{-6}sec$, the substrate must be thicker than $70{\mu}m$, while for materials with a lifetime shorter than $5{\times}10^{-6}sec$, the substrate must be thinner than $70{\mu}m$. In substrate fabrication, the thinner the wafer, the lower the cost of material, but the higher the cost of wafer fabrication. Thus, the optimum thickness/lifetime combinations are defined in this study along with the substrate cost considerations as part of the factors to be considered in material selection.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 D
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• pp.1361-1363
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• 1998

Poly-Si grain boundaries act as potential barriers as well as recombination centers for the photo-generated carriers in solar cells. Thereby, grain boundaries of poly-Si are considered as a major source of the poly-Si cell efficiency was reduced This paper investigated grain boundary effect of poly-Si wafer prior to the solar cell fabrication. By comparing I-V characteristics inner grain, on and across the grain boundary, we were able to detect grain potentials. To reduce grain boundary effect we carried out pretreatment, $POCl_3$ gettering, and examined carrier lifetime. This paper focuses on resistivity variation effect due to grain boundary of poly-Si. The resistivity of the inner grain was $2.2{\Omega}-cm$, on the grain boundary$2.3{\Omega}-cm$, across the grain boundary $2.6{\Omega}-cm$. A measured resistivity varied depending on how many grains were included inside the four point probes. The resistivity increased as the number of grain boundaries increased. Our result can contribute to achieve high conversion efficiency of poly-Si solar cell by overcoming the grain boundary influence.

• Current Photovoltaic Research
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• 제5권1호
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• pp.25-27
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• 2017

Nanoscale textured black silicon has attracted intensive attention due to its great potential as applications in multicrystalline silicon-based solar cells. It absorbs sunlight over a broad range of wavelengths but introduces large recombination centers, non-uniform doping into cell. In this study, we present a metal-assisted chemical etching technique plus alkaline etching process to fabricate nanoscale pyramid structures with optimized condition. To make the structures, silver nanoparticles-loaded mc-Si wafer was submerged into $H_2O_2/HF$ solution first for nanohole texturing the wafer and textured wafer etched again with KOH solution for making nanoscale pyramid structures. The average reflectivity (350-1050 nm) is about 8.42% with anti-reflection coating.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.50.1-50.1
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• 2010

결정질 실리콘 태양전지의 원가에서 Wafer는 60~70%의 매우 높은 비중을 차지하고 있다. 많은 연구들이 원가 절감을 위하여 Wafer의 두께를 감소시키는 것에 집중하고 있다. 그러나 Wafer 두께의 감소는 태양전지의 효율 감소와 공정 진행 중에 파손율이 상승하는 등의 문제가 발생한다. 이에 본 논문에서는 결정질 태양전지 구조 중에서 24.7% 이상의 최고 변환 효율을 갖는 PERL(Passivated Emitter, Rear Locally diffuse) 구조를 대상으로 wafer 두께 감소에 따른 변환 효율 감소의 원인과 해결 방안을 제시하고자 한다. Simulation으로 확인한 결과 370 um 두께의 wafer에서 24.2 %의 효율은 50 um 두께의 wafer에서는 20.8 %로 감소함을 확인할 수 있었다. 얇아진 wafer에서 감소한 효율을 개선하기 위하여 후면 recombination velocity, 후면 fixed charge density, 후면 산화막 두께 등을 다양화하여, 각각의 경우에 대한 cell의 효율 변화를 살펴보았다. 그 결과 후면 recombination velocity, 후면 fixed charge density, 후면 산화막 두께를 최적화 하여, 각각 2.8 %p, 1.5 %p, 2.8 %p의 효율 개선 효과를 얻었다. 위 세 가지 효과를 동시에 적용하면 50 um wafer에서 370 um wafer 효율의 결과와 근접한 24.2 %의 효율을 얻을 수 있었다. 향후에는 위의 결과를 바탕으로 실제 실험을 통하여 확인할 계획이다.

• 한국재료학회지
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• 제25권1호
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• pp.16-20
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• 2015

In this study, in order to improve the efficiency of n-type monocrystalline solar cells with an Alu-cell structure, we investigate the effect of the amount of Al paste in thin n-type monocrystalline wafers with thicknesses of $120{\mu}m$, $130{\mu}m$, $140{\mu}m$. Formation of the Al doped $p^+$ layer and wafer bowing occurred from the formation process of the Al back electrode was analyzed. Changing the amount of Al paste increased the thickness of the Al doped $p^+$ layer, and sheet resistivity decreased; however, wafer bowing increased due to the thermal expansion coefficient between the Al paste and the c-Si wafer. With the application of $5.34mg/cm^2$ of Al paste, wafer bowing in a thickness of $140{\mu}m$ reached a maximum of 2.9 mm and wafer bowing in a thickness of $120{\mu}m$ reached a maximum of 4 mm. The study's results suggest that when considering uniformity and thickness of an Al doped $p^+$ layer, sheet resistivity, and wafer bowing, the appropriate amount of Al paste for formation of the Al back electrode is $4.72mg/cm^2$ in a wafer with a thickness of $120{\mu}m$.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2008년도 제35회 하계학술대회 초록집
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• pp.325-326
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• 2008

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2009년도 추계학술발표대회 논문집
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• pp.350-355
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• 2009

The crysralline silicon solar cell where the solar cell market grows rapidly is occupying of about 85% or more high efficiency and low cost endeavors many crystalline solar cells. The fabricaion process of high efficiency crystalline silicon solar cells necessitate complicated fabrication processes and Ti/Pd/AG contact, This metal contacts have only been used in limited areas in spite of their good srability and low contact resistance because of expensive materials and process. Commercial solar cells with screen-printed solar cells formed by using Ag paste suffer from loe fill factor and high contact resistance and low aspect ratio. Ni and Cu metal contacts have been formed by using electroless plating and light-induced electro plating techniques to replace the Ti/Pd/Ag and screen-printed Ag contacts. Copper and Silver can be plated by electro & light-induced plating method. Light-induced plating makes use the photovoltaic effect of solar cell to deposit the metal on the front contact. The cell is immersed into the electrolytic plating bath and irradiated at the front side by light source, which leads to a current density in the front side grid. Electroless plated Ni/ Electro&light-induced plated Cu/ Light-induced plated Ag contact solar cells result in an energy conversion efficiency of 16.446 % on 0.2~0.6${\Omega}$ cm, $20{\times}20mm^2$, CZ(Czochralski) wafer.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 추계학술발표대회 논문집
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• pp.245-248
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• 2011

Many researches have been carried out to improve light absorption in the crystalline silicon solar cell fabrication. The rear reflection is applied to increase the path length of light, resulting in the light absorption enhancement and thus the efficiency improvement mainly due to increase in short circuit current. In this paper, we manufactured the silicon solar cell using the mono crystalline silicon wafers with $156{\times}156mm^2$, 0.5~3.0 ${\Omega}{\cdot}cm$ of resistivity and p-type. After saw damage removal, the dielectric film ($SiN_x$)on the back surface was deposited, followed by surface texturing in the KOH solution. It resulted in single-side texturing wafer. Then the dielectric film was removed in the HF solution. The silicon wafers were doped with phosphorus by $POCl_3$ with the sheet resistance 50 ${\Omega}/{\Box}$ and then the silicon nitride was deposited on the front surface by the PECVD with 80nm thickness. The electrodes were formed by screen-printing with Ag and Al paste for front and back surface, respectively. The reflectance and transmittance for the single-sided and double-sided textured wafers were compared. The double-sided textured wafer showed higher reflectance and lower transmittance at the long wavelength region, compared to single-sided. The completed crystalline silicon solar cells with different back surface texture showed the conversion efficiency of 17.4% for the single sided and 17.3% for the double sided. The efficiency improvement with single-sided textured solar cell resulted from reflectance increase on back surface and light absorption enhancement.

• 한국산학기술학회논문지
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• 제4권1호
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• pp.47-49
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• 2003

태양전지에 소모되는 비용중의 30% 이상이 silicon 기판의 가공 및 silicon자체의 비용이다. 본 연구에서는 이러한 비운을 절감하기 위해 silicon기판대신 STS 304를 사용하고자 한다. STS 304를 태양전지용 기판으로 사용하기 위해서는 고도천 연마된 표면을 필수조건으로 하기 때문에 STS 304에 전해연마를 실시하여 AFM으로 표면의 거칠기를 살펴보았다 또 한, 표면 조도의 향상을 위해 최적의 연마조건에서 leveller를 첨가하였다. 인산($H_3PO_4$)을 기본으로 한 전해연마액에 2A의 전류와 극간거리 0.7cm의 조건하에서 STS 304의 최적 전해연마조건을 찾기 위해 전해액의 온도는 $80^{\circ}C{\sim}120^{\circ}C$, 연마시간은 3~2분간 전해연마를 실시하였다. 그 결과 2A/$cm^2$, $80^{\circ}C$, 10분에서 27.9nm의 표면조도를 보였으며, leveller로 사용된 glycerine, ethylene glycol, propylene glycol의 영향을 연구하였다. Leveller 중에서는 ethylene glycol을 0.4g/l 첨가하였을 때 표면조도가 약 15nm로서 그 효과가 가장 좋았다.