Impact of temperature and doping on LETID and regeneration in mc-Si

Abstract

Light and elevated temperature induced degradation can be observed in multicrystalline Si PERC solar cells and results in efficiency losses of up to 12%rel. This work investigates the impact of temperature as well as doping on the degradation and regeneration behavior of lifetime samples. While ungettered Ga-doped samples did not show any regeneration effect within the duration of the experiment, increasing the treatment temperature sped up the degradation and regeneration where it could be observed. Ga-doped samples showed a slower degradation compared to B-doped samples. For higher temperatures (≥200°C) the lifetimes during regeneration exceeded the initial lifetimes before starting the illumination treatment for the gettered samples. After regeneration at higher temperature, the stability of lifetime at 75°C was tested. When tested after treatment at 150°C and before the lifetime exceeded the initial value, it stayed stable. After treatment at 250°C until the lifetime exceeded the initial lifetime, it decreased again during the stability test. However, the kinetics of this decrease was much slower than during the initial degradation.