Fabrication of Poly-Si on Locally Etched SiOx as Passivating Contacts for c-Si Solar Cells

Polysilicon on silicon oxide (poly-Si/SiOx) passivating contacts with predominant charge-carrier transport via pinholes were prepared with room temperature metal-assisted chemical etching. Pinhole areal densities in the range of 2.8x10(4) to 4.5x10(7) cm(-2) were imaged by SEM. Contact resistivity of 32 m-ohm-cm(2) and implied open circuit voltage of 729 mV were obtained for symmetric n+ poly-Si/SiOx grown onto randomly textured n-Cz. We also show preliminary data pertaining boron-doped polysilicon on nitride/oxide passivating contacts, with which we achieved implied open circuit voltage above 730 mV and recombination current of 0.2 fA/cm(2).