Fast co-diffusion process for bifacial n-type solar cells

We present a new simplified and fast process sequence for the fabrication of large area bifacial n-type silicon solar cells. A co-diffusion process simultaneously forms the boron-doped emitter and the phosphorus-doped back surface field in one single high temperature step. We use borosilicate glasses (BSG) deposited by atmospheric pressure chemical vapor deposition (APCVD) and a POCl3 gas ambient as doping sources. Tailoring of the diffusion process yields a reduced co-diffusion process time of 114 min, well suited for production. The presented co-diffusion process allows a lean fabrication process. A proof of concept experiment leads to 20.1% bifacial n-type solar cells.