Light-triggered defect dynamics in silicon wafers: understanding degradation mechanisms

In this work, the effect of heat treatment on the minority carrier lifetime (τ) in boron-doped crystalline silicon wafers coated with a silicon nitride (SiNx:H) layer has been investigated. The results showed an initial increase in τ during the early phase of light exposure of the samples, which was attributed to the presence of iron–boron complexes in the c-Si wafers. However, this enhancement was followed by a decrease associated with the formation of boron-oxygen complexes, known as light-induced degradation. Moreover, kinetic models were used to analyze defect interactions in the wafers, showing a correlation between τ behavior and hydrogen-boron complex concentrations, and related by analytical techniques. In addition, the samples were subjected to a dark annealing step, resulting in further degradation due to the firing temperature process and the presence of hydrogen atoms in the silicon nitride layer. Finally, this study provides valuable insights into defect formation mechanisms in c-Si wafers that could improve the stability and efficiency optimization of silicon-based solar cells under operating conditions.