The application of poly-Si/SiOx contacts as passivated top/rear contacts in Si solar

Passivated contacts based on low-pressure chemical vapor deposited (LPCVD) heavily-doped poly-Si and a thin SiOx layer are explored for the application in an interdigitated back contact (IBC) solar cell. The poly-Si/SiOx contacts are realized by applying wet-chemically grown SiOx tunnel layers and amorphous Si (a-Si) layers doped via ion implantation that are subsequently transformed into poly-Si/SiOx contacts by a high temperature step. The impact of doping species, ion dose, and poly-Si thickness on the surface passivation of such contacts is studied. Excellent J0 values down to 4.5 fA/cm(2) were measured for n(+) -poly -Si contacts, while J0 values as low as 22 fA/cm(2) were obtained for p(+) -poly-Si contacts. Solar cells with top/rear poly-Si contacts were processed and V-oc values up to 709 mV and FF values above 81% were measured. Furthermore, the upper bound for the parasitic absorption losses in 10-40 nm thick poly-Si films was quantified to be about 0.5 mA/cm(2) per 10 nm poly-Si layer thickness. (C) 2016 Elsevier B.V. All rights reserved.