Increased wafer yield in silicon ingots by the application of high purity silicon nitride-coating and high purity crucibles

Multi-crystalline silicon is usually grown in fused silica crucibles, the inner walls of which are coated with silicon nitride. The influence of the purity of the silicon nitride coating and of the fused silica crucible on the minority-carrier lifetime and infrared transparency of the bricks has been monitored. The results indicate that the purer the silicon nitride the higher the minority-carrier lifetime of the crystallized ingot and the higher the yield of highly efficient solar cells per ingot. Also, the purity of the fused silica crucible seems to be affecting the minority carrier lifetime.