Purification Efficiency and B Removal of Polysilicon during its Solidification from a Si-Al-Sn Melt

Solar grade silicon (SoG-Si) is the basic material of photovoltaic industry. Metallurgical method as a way of purification isconsidered to reduce the cost of polysilicon production unanimously based on its low cost, short production cycle, relatively simple process, lowpollution and controllable scale size, and it has become a hot topic in the subject research around the world.In this paper Al-Si-Sn alloy is used to purifypolysiliconand influence on the purification efficiency of polysilicon with different compositions of Al-Si-Sn alloy is analyzed. In order to study the segregation of impurity B in purification process, we introduce final segregation coefficient kB,finaland analyze the relation between kB,finaland the content of Al,Snin Al-Si-Sn alloy thermodynamically.