Low-Temperature Purification of Silicon by Dissolution and Solution Growth in Sodium Solvent
Low-Temperature Purification of Silicon by Dissolution and Solution Growth in Sodium Solvent
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DOI：
10.1007/s12633-011-9105-8
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发表时间：
2012-03
期刊：
影响因子：
3.4
通讯作者：
H. Morito;Taiki Karahashi;M. Uchikoshi;M. Isshiki;H. Yamane
中科院分区：
文献类型：
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作者：
H. Morito;Taiki Karahashi;M. Uchikoshi;M. Isshiki;H. Yamane
为了克服硅的供应不足，需要高效低成本的太阳级硅生产工艺。我们展示了一种提纯硅晶体的新方法。将低纯度的Si粉末溶解在Na熔体（溶剂）中，在1173 K下，通过Na-Si溶液中的Na蒸发使Si晶粒结晶。辉光放电质谱分析表明，除Na和B外，Si晶粒中其他杂质元素的浓度均有所降低。特别是，在精细化的Si晶粒中，主要包含在Si粉中的Fe的质量浓度从3200ppm下降到1.5 ppm。二硅化铁在硅结晶之前先从溶液中结晶。认为杂质的减少不仅是由于Na-Si熔体的结晶作用，而且是由于Si在熔体中的溶解作用。在真空条件下，在1723 K的温度下加热，将Na对Si晶粒的污染降低到0.055质量ppm。
Efficient low-cost processes for solar-grade Si production are needed to overcome the deficiency in the supply of Si. We have demonstrated a new method for the purification of Si crystal. Low-purity Si powder was dissolved in a Na melt (solvent), and Si grains were crystallized by Na evaporation from the Na-Si solution at 1173 K. Glow discharge mass spectrometry analysis revealed that the concentrations of impurity elements, except Na and B, were decreased in the crystallized Si grain. In particular, the concentration of Fe which was mainly included in the Si powder decreased from 3200 ppm by mass to 1.5 ppm by mass in a refined Si grain. Iron disilicide was crystallized from the solution before the crystallization of Si. It was suggested that impurities were reduced not only by crystallization from the Na-Si melt but also by the dissolution of Si into the melt. Na contaminating the refined Si grain was eliminated down to 0.055 mass ppm by heating at 1723 K under vacuum.