EU PVSEC Programme Online
EU PVSEC 2020, 7 - 11 September 2020
Presentation: 2BO.2.2 Influence of Low-Temperature Annealing before Firing on LeTID in Multicrystalline Silicon
Type: Oral
Date: Tuesday, 25th September 2018
13:30 - 15:00
Location / Room: SQUARE - Brussels Meeting Centre Level 0 / Gold Hall
Author(s): A. Schmid, J. Lindroos, A. Zuschlag, D. Skorka, J. Fritz, G. Hahn
Presenter / Speaker: A. Schmid, University of Konstanz, Konstanz, Germany
Event: Conference Conference
Session: 2BO.2 Defect Engineering in Silicon
Type(s) of Access:  Conference Registration
Topic: 2. 1 Feedstock, Crystallisation, Wafering, Defect Engineering
Keywords: Annealing, Degradation, Lifetime, Hydrogen, Multicrystalline Silicon, LeTID
Summary / Abstract: Light and elevated temperature induced degradation (LeTID) affects significantly the performance of multicrystalline silicon (mc-Si) solar cells. Even though the underlying mechanisms of LeTID and subsequent regeneration are still unknown, LeTID formation is known to be influenced by surface passivation, firing, and lowtemperature annealing after firing. Since both the firing peak temperature and the cooling profile strongly influence LeTID, firing is presumed to dominate over any preceding low-temperature steps. However, lifetime measurements during illumination (1.0 ±0.1 suns) at 150°C show a clear difference in the LeTID defect density in samples annealed at 200-500°C before aluminum oxide deposition and before firing. Additionally, LeTID becomes worse when the prefiring annealing is performed in an H plasma atmosphere. Therefore, the firing step does not erase the impact of lowtemperature annealing or pre-firing hydrogenation on LeTID. Finally, thinner samples are shown to cause lower initial effective lifetimes (eff) and less LeTID.