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 $\text{n}^{\mathbf {+}}$-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 $^{\mathbf {sequence\, where\, the\, POCl}}$3$^{\mathbf {-diffusion\, and\, SiN}} \mathbf {x}$deposition are replaced by the POLO junction formation processes. The implied $^{\mathbf {open\, circuit\, voltage\, iV}} \mathbf {oc}$ measured on these devices reaches up to 708 mV (684 mV) under 1 sun (under filtered spectrum), respectively.