Photoluminescence (PL) imaging techniques combined with a minority carrier lifetime measurement system were utilized to investigate the effects of heating temperature on the interstitial iron (Fei) concentration, the recombination activity of structural defects, and the minority carrier lifetime in cast multicrystalline silicon (mc-Si). The results indicate that heating mc-Si wafers to 800 °C followed by natural cooling led to a 21.4% increase in Fei concentration, a 121% increase in recombination-active dislocations, a 142% increase in recombination-active grain boundaries, a 158% rise in the “dark area percentage,” and a 46.6% decrease in minority carrier lifetime. When the heating temperature was increased to 1000 °C followed by natural cooling, the Fei concentration rose by a factor of 11.87, and the “dark area percentage” increased by 8668%, suggesting widespread metal impurity—particularly iron contamination across the entire wafer, which resulted in an extremely low minority carrier lifetime of only 0.224 μs.
Zhou et al. (Wed,) studied this question.