• 한국결정성장학회지
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• 제18권5호
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• pp.195-199
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• 2008

반도체용 규소 원료는 11 N급의 고순도이나 가격이 고가이고 또한 생산이 제한되어서 폭발적인 태양전지의 수요를 따르지 못하고 있어 저급(5$\sim$6 N)의 UMG(Upgraded Metallurgical Grade)를 사용하자 하는 노력이 진행 중이다. 이 5$\sim$6 N급에서는 dopant 원소인 붕소(B)외 인(P)의 농도가 1 ppm 이상 존재한다. 이들 원료를 사용하여서 결정 성장을 하였을 경우에 존재하는 여러 불순물들의 편석계수(segregation coefficient)를 활용하여 화학적, 전기적 성질을 예상 하여본 결과 결정성장 초기에는 붕소(B)의 농도가 인(P) 보다 높아 p영역이 발생하고 후반부에는 인의 농도가 붕소 보다 높아 n 형 기판이 생성됨을 보았다. 또한 응고속도를 조절하여 여러 불순물을 제거하고자 히는 노력은 편식계수가 적은 금속 일소들의 제거에는 효과적이나 편석계수가 큰 붕소와 인의 제거에는 효과가 크지 않음을 예상 할 수 있다.

• 한국세라믹학회지
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• 제47권6호
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• pp.618-622
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• 2010

Cost-effective purification methods of silicon were carried out in order to replace the conventional Siemens method for solar grade silicon. Firstly, acid leaching which is a hydrometallurgical process was preceded with grinded silicon powders of metallurgical grade (~99% purity) to remove metallic impurities. Then, plasma treatments were performed with the leached silicon powders of 99.94% purity by argon plasma at 30 kW power under atmospheric pressure. Plasma treatment was specifically efficient for removing Zr, Y, and P but not for Al and B. Another purification step by EB treatment was also studied for the 99.92% silicon lump which resulted in the fast removal of boron and aluminum. That means the two methods are effective alternative tools for removing the doping elements like boron and phosphor.

• 한국주조공학회지
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• 제14권1호
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• pp.28-34
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• 1994

Metallurgical-grade polycrystalline silicon was directionally solidified at growth rates of $0.2{\sim}1.0mm/min$ by using split type, reusable graphite molds which were coated with $Si_3N_4$ powder. The resultant grain sizes of the silicon ingots and the shapes of the solid/liquid(S/L) interfaces were investigated. X-ray diffraction was used to determine the preferred orientation in each of the silicon ingots. The impurity content of the silicon was analyzed and the resistivities of the ingots were measured. During the growth of an ingot, the shape of the S/L interface was concave to the silicon melt, and the resistivity decreased. The presence of Al which can be acting as a carrier, is thought to be the main factor causing such a decrease in resistivity. When a growth rate of 0.2㎜/min was used, the preferred orientation was found to be (111).

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.111.1-111.1
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• 2011

The solar energy is dramatically increasing as the alternative energy source and the silicon(Si) solar cell are used the most. In this study, the improved process and equipment for the metallurgical refinement of multicrystalline Si were evaluated for the inexpensive solar cell. The planar plane and columnar dendrite aheadof the liquid-solid interface position caused the superior segregation of impurities from the Si. The solidification rate and thermal gradient determined the shape of dendrite in solidified Si matrix solidified by the directional solidification(DS) method. To simulate this equipment, the commercial software, PROCAST, was used to solve the solidification rate and thermal gradient. Si was vertically solidified by the DS system with Stober process and up-graded metallurgical grade or metallurgical grade Si was used as the feedstock. The inductively coupled plasma mass spectrometry (ICP) was used to measure the concentration of impurities in the refined Si ingot. According to the result of ICP and simulation, the high thermal gradient between the two phases wasable to increase the solidification rate under the identical level of refinement. Also, the separating heating zone equipped with the melting and solidification zone was effective to maintain the high thermal gradient during the solidification.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.43.2-43.2
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• 2010

In this study, metallurgical grade (MG) silicon with 99% purity produced by arc furnace process was systematically investigated for slag refining. The most problematic impurities to remove from MG silicon are boron (B) and phosphorus (P). To remove B and P from MG-silicon, we used synthetic slag in the molten state. MG-silicon with synthetic slag of CaO, $SiO_2$, and $CaF_2$ was melted using by high-frequency induction furnace with electrical output of 50kW. Specimens prepared by various refining process conditions(holding time, mixture ratio) were inspected by combined analysis of ICP-MS and XRF. With this approach, B has been reduced to <5ppm, P to <1ppm and other impurities to 0.1~0.2% except for Calcium. Calcium has been increased from 17ppm to 1500ppm. Problem of calcium contamination will be resolved by additional refining processes.

• 한국광물학회지
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• 제22권3호
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• pp.191-197
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• 2009

고순도 금속급 실리콘 제조에서는 원료가 되는 실리카 광물의 $SiO_2$ 품위가 매우 중요한 요소이다. 베트남 규사광에 대한 광물학적 분석결과를 토대로, 석영과 불순광물의 광물학적 특성차이를 이용하는 분급, 비중 및 자력선별을 포함하는 물리적 종합정제공정을 구성하여 적용시켰다. $SiO_2$ 품위 99.8 wt% 이상의 고순도 규사 정광을 93 wt% 이상 회수하였다. 이러한 고순도 규사 정광은 금속급 실리콘의 순도 규격에 적합하였다.

• 한국산학기술학회논문지
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• 제18권11호
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• pp.118-123
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• 2017

다양한 산업에 사용되고 있는 금속급 실리콘(MG-Si, Metallurgical grade silicon)을 제조하기 위해 실리콘 원료 내 가장 많이 함유하고 있는 불순물인 알루미늄(Al) 및 철(Fe)을 제거하고자 산(Acid) 침출 실험을 수행하였다. 5가지 종류의 산(HCl, HF, H2SO4, HNO3, H3PO4)을 1, 2, 4, 6M로 조제하여 실리콘 원료에 반응시킨 결과, 1M 농도의 HF가 가장 우수한 Al 및 Fe 제거율을 나타내었으며 각각 97.9%와 95.2로 나타났다. 그러나 HF는 실리콘 부식 특성으로 인해 18% 가량의 수율 감소가 발생하였으며 이러한 수율감소를 최소화하기 위해 두 번째로 제거율이 우수하게 나타난 2M HCl과 혼합하여 실리콘 원료에 적용하였다. 혼합용액의 최적조건을 선정하기 위해 실험을 수행하여 $80^{\circ}C$, 2시간의 침출 최적조건으로 결정되었으며 이 혼합용액의 적용 결과 Al 및 Fe 잔류농도가 각각 141 ppmw 및 93ppmw로 나타나 3N급의 순도를 갖는 금속급 실리콘을 제조하기에 매우 용이한 것으로 확인되었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.438-438
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• 2009

We have investigated the effect of forming gas annealing for Upgraded Metallurgical Grade (UMG)-silicon solar cell in order to obtain low-cost high-efficiency cell using post deposition anneal at a relatively low temperature. We have observed that high concentration hydrogenation effectively passivated the defects and improved the minority carrier lifetime, series resistance and conversion efficiency. It can be attributed to significantly improved hydrogen-passivation in high concentration hydrogen process. This improvement can be explained by the enhanced passivation of silicon solar cell with antireflection layer due to hydrogen re-incorporation. The results of this experiment represent a promising guideline for improving the high-efficiency solar cells by introducing an easy and low cost process of post hydrogenation in optimized condition.

• 자원리싸이클링
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• 제30권4호
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• pp.20-26
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• 2021

태양전지용 실리콘은 주로 반도체급 실리콘 제조공정에서 발생하는 규격외 실리콘을 사용하여 왔다. 태양전지의 보급 활성화를 위해서는 보다 저렴한 정제 공정의 개발이 필요하다. 태양전지용 실리콘을 위한 저비용이면서 효율적인 방법은 금속급 실리콘을 정제하여 고순도화하는 것이다. 본 연구에서는 금속급 용융 실리콘 중의 Fe를 제거하기 위해 고주파 유도로 중에서 일방향 응고를 실시하였다. 실험조건과 실험결과를 유효 편석계수, Scheil 식 및 Peclet 수로 평가하였다. 시료의 하강속도가 감소함에 따라 불순물의 매크로 편석과 잉곳의 순도가 증가하였다. 이러한 결과는 시료의 하강속도 감소에 따른 유효 편석계수의 감소에 의한 것으로 생각된다.

• 한국세라믹학회지
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• 제48권2호
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• pp.189-194
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• 2011

Metallurgical grade silicon was recovered from slurry waste for ingot sawing process by acid leaching and thermal treatment. SiC abrasive was removed by gravity concentration and centrifugation. Metal impurities were removed by the acid leaching using HF/HCl. The remaining SiC was separated by the thermal treatment at $1600^{\circ}C$ in an inert atmosphere by the difference in melting points. The purity of the obtained silicon was found to be around 99.7%.