p+/n+ polysilicon-on-oxide tunneling junctions as an interface of p-type PERC cells for tandem applications

We present a novel cell concept that combines the tandem cell approach with the PERC mainstream technology. As an interface between Si bottom and top cell, we utilize passivating n
⁺
-type polysilicon on oxide (POLO) contacts and a p+ poly-Si / n
⁺
poly-Si tunneling junction. Our full area PERC
⁺
Si bottom cells are fabricated within a typical industrial process sequence where the POCl
₃
-diffusion and SiN
_x
deposition are replaced by the POLO junction formation processes. The implied open circuit voltage iV
_oc
measured on these devices reaches up to 708 mV (684 mV) under 1 sun (under filtered spectrum), respectively.