Poly-Si (n) Removal for TOPCon Solar Cells

This work gives results on wet chemical parasitical polysilicon removal for tunnel oxide passivated contact (TOPCon) n-type silicon solar cells. The poly-Si removal is important to fabricate TOPCon cells with low reverse bias junction leakage current density (jrev,2). TOPCon solar cells with in-situ n-doped LPCVD and PECVD poly-Si layers were fabricated with wet chemical inline and wet chemical batch poly-Si removal processes. Our results show that a wet chemical alkaline batch removal for parasitical PECVD poly-Si is possible using the anneal oxide from N2 anneal process to protect the functional poly-Si on rear. This batch process led to an efficiency of 23.4% solar cell with in-situ doped PECVD poly-Si.