Purity of silicon ingot made of the silicon flakes obtained by the combination of solvent refining and centrifugation from Al-Si alloy melts

摘要

Silicon flakes were obtained from Al-30wt.％ Si alloy melt by using a combined method of solvent refining and centrifugal separation and by subsequent acid leaching.Then they were melted in a silica crucible with 50mm diameter,and were grown in a directional solidification furnace at different growth rate between 0.3 and 0.7mm/min.Purity of silicon was greatly improved and depended on the growth rate.It was successful to get high purity silicon over 4N from 2N purity silicon.This combined process is expected to drive down the cost of manufacturing solar-grade silicon significantly,and to make solar power more competitive than other options to generate electricity.