A modified cooling process in directional solidification of multicrystalline silicon

Directional solidification is the most popular technique for massive production of multicrystalline silicon in the solar industry. Conventional process aims to prevent the breakage of silicon ingots. To lower dislocation density in ingots, a significant modification to conventional cooling processes in productions of mc-Si ingots is proposed, and a three-dimensional numerical simulation with a simplified model of dislocation multiplication has been carried out to analyze its effect on dislocation multiplication. The results show that with the modified cooling process, the final dislocation density could be reduced to about one fifth of that formed in normal cooling process.