Effect of the Si_3N_4 coating on the mc-Si ingot in the process of multicrystalline silicon purification by metallurgical methods

摘要

The Si_3N_4 protective coating has an important impact on avoiding melting silicon from contacting with the crucible wall directly. A mixed Si/Si_3N_4 layer was formed on the interface of silicon and Si_3N_4 coating, and the declination of N content was observed in this mixed layer. With the ingots condition of 1500℃ for 2 h, the large Si_3N_4 and SiC particles appeared in the mixed layer and the formation mechanism was discussed. The Si_3N_4 coating had significantly increased the lifetime of minority carriers by decreasing impurity content.