LPCV-Deposited Poly-Si Passivated Contacts: Surface Passivation, Gettering and Integration in High Efficiency Devices

In this paper, we present our latest developments in n+ poly-Si/SiO x passivated contacts elaborated on a high throughput LPCVD furnace as well as their integration in high efficiency large area n-type PERT solar cells. Both in-situ and ex-situ doping of the poly-Si layer have been investigated. Following a fine tuning of the thin oxide layer growth and of the poly-Si doping process, iVoc up to 735 mV could be reached on symmetrical samples with Cz silicon wafers. The high performances of this structure were also confirmed on advanced cast mono wafers with similar iVoc levels. Finally, a fabrication process based on high throughput industrial equipment from SEMCO SMARTECH was developed to form high efficiency polySi based PERT solar cells. Efficiency values up to 22.8% were measured on large area Cz silicon wafer using a standard 5 busbars screen printed metallization.