Influence of Al2O3 and SiNx passivation layers on LeTID

In this work the carrier lifetime evolution of different passivation layers under illumination and at elevated temperatures are investigated. Multicrystalline silicon lifetime samples were treated by implementing typical industrial processing steps. The degradation was found to depend strongly on surface passivation type, but is independent of the surface doping and oxide charge. The influence of the passivation layer on the silicon bulk lifetime degradation is investigated. After reaching a degradation maximum, the lifetime samples feature a regeneration phase. Capacitance-voltage measurements show that the oxide charge is not influenced by the degradation, but a high decrease in carrier lifetime were measured. Firing experiments show that lifetime samples passivated after firing procedure are not prone to degradation. (C) 2016 The Authors. Published by Elsevier Ltd.