I. Introduction
Light- and elevated temperature-induced degradation (LeTID [1]) is known to negatively impact the high-efficiency passivated emitter and rear cell concept, as first observed in multicrystalline silicon (mc-Si) [2]. It has been shown that LeTID can cause an efficiency loss of up to 10%rel on cell level already during the first several hundred hours of illumination (depending on temperature and injection conditions) [1] but also impacts effective minority charge carrier lifetime (τeff) samples [3], [4] and may be followed by a phase of regeneration. The observed effect cannot be described by the boron-oxygen (BO) related degradation or FeB pair dissociation [2], [5]. It has been proven that LeTID occurs in both B- and Ga-doped mc-Si [2], [6], and further that Czochralski-grown (Cz) and float zone (FZ) Si materials are also affected by this kind of defect [7]–[10]. As in Cz-Si the BO defect formation also leads to a severe reduction of τeff, both degradation phenomena are usually measured in parallel, but recent studies already showed a way to identify the dominant defect [11].