Investigating the Origins of Surface Passivation Degradation in n+ and p+ Poly-Si/SiOx Passivating Layers for Silicon Solar Cells

Poly-Si/SiOx passivating contact silicon solar cells have reached very high efficiencies. The PV industry is rapidly moving from the conventional passivated emitter and rear contact cell (PERC) to the Tunnel oxide passivating contact cells (TOPCon). With the remarkable efficiencies and market share shift, the imperative now moves towards determining the long-term stability of passivating contacts cells including both polarities of the poly-Si/SiOx contacts. Several studies have identified a low temperature degradation/regeneration mode in n+ poly-Si contacts post firing. In this work we investigate the underlying factors contributing to the degradation of both n+ and p+ poly-Si/SiOx passivating contacts for n-type Cz silicon solar cell, by exploring the hypothesis that the degradation is caused by the formation of pinholes in the tunneling oxide layer.