Growth Process Improvement for Casting High-Performance Multi-Crystalline Silicon Ingots for Solar Cells

Abstract

An improved growth process was proposed to produce the high-quality multi-crystalline silicon ingots for solar cells. A transient numerical model was used to investigate the effects of the growth process design parameters on the crystal-melt (c-m) interface, the melt convection and the thermal stress distribution during the growth process. The simulation results showed that compared with the original design, the almost flat c-m interface, the favorable melt convection and the much lower thermal stress were obtained with the improved design. Ingot casting experiments were performed for the two designs. The average yield rate of silicon ingots was 3.69% higher in absolute value with the improved design, and the interstitial oxygen content of silicon wafers was lower. The average conversion efficiency of p-type solar cells was 0.18% higher in absolute value with the improved design (18.59%) than that with the original design (18.41%).