Evolution of the light sensitive defects in high performance multicrystalline silicon wafers

Abstract

Sequential degradation measurements have been performed on passivated high performance multicrystalline silicon wafers, first at room temperature under low intensity illumination followed by a higher intensity illumination at an elevated temperature. The presence of two main degradation mechanisms, affecting the lifetime under different conditions has been demonstrated, namely, the well-studied light induced degradation caused by boron-oxygen-complexes and the less understood light and elevated temperature induced degradation. Light and elevated temperature induced degradation is the main lifetime limiting the recombination path when fully activated, but the contribution from boron-oxygen complexes is not negligible. This separation of the two degradation mechanisms might, therefore, be necessary for proper evaluation of the dominant recombination mechanism. Experiments also show regeneration of the minority carrier lifetimes caused by deactivation of both the lifetime limiting defects at comparable time scales, and under similar illumination and temperature conditions. Wafers from different heights in a high performance multicrystalline silicon ingot have been evaluated to better understand the underlying causes for the different degradation mechanisms. Effects of the iron-boron-splitting on the carrier lifetime are only visible in ungettered wafers.Sequential degradation measurements have been performed on passivated high performance multicrystalline silicon wafers, first at room temperature under low intensity illumination followed by a higher intensity illumination at an elevated temperature. The presence of two main degradation mechanisms, affecting the lifetime under different conditions has been demonstrated, namely, the well-studied light induced degradation caused by boron-oxygen-complexes and the less understood light and elevated temperature induced degradation. Light and elevated temperature induced degradation is the main lifetime limiting the recombination path when fully activated, but the contribution from boron-oxygen complexes is not negligible. This separation of the two degradation mechanisms might, therefore, be necessary for proper evaluation of the dominant recombination mechanism. Experiments also show regeneration of the minority carrier lifetimes caused by deactivation of both the lifetime limiting defects at comparable time ...