定向凝固技术的发展及其在制备太阳能级硅材料中的应用

讲述了定向凝固技术的发展历程,简要介绍了各种定向凝固技术的原理和特点并对其进行了评述。从定向凝固技束的演化过程看,是温度梯度不断提高．冷却速度不断加快的过程。介绍了定向凝固技束在制备太阳能级硅材料中的应用,并对其存在问题及发展趋势进行了讨论。     

Vacuum distillation refining of metallurgical grade silicon （Ⅰ） ——-Thermodynamics on removal of phosphorus from metallurgical grade silicon

The removal of impurity phosphorus from metallurgical grade silicon is one of the major problems on purification of metallurgical grade silicon for solar grade silicon preparation. The thermodynamics on vacuum refining process of the metallurgical grade silicon was studied via separation coefficient of impurity phosphorus in the metallurgical grade silicon and vapor-liquid equilibrium composition diagram of Si-P binary alloy at different temperatures. The behaviors of impurity phosphorus in the vacuum distillation process were examined. The results show that the vacuum distillation should be taken to obtain silicon with less than 10^-7 P, and the impurity phosphorus is volatilized easily by vacuum distillation in thermodynamics. Phosphorus is distilled from the molten silicon and concentrated in vapor phase.