Plasma immersion ion implantation of boron for ribbon silicon solar cells

Abstract

In this work, we report for the first time on the solar cell fabrication on n-type silicon RST (for Ribbon on Sacrificial Template) using plasma immersion ion implantation. The experiments were also carried out on FZ silicon as a reference. Boron was implanted at energies from 10 to 15 kV and doses from 10 15 to 10 16 cm −2 , then activated by a thermal annealing in a conventional furnace at 900 and 950• C for 30 min. The n + region acting as a back surface field was achieved by phosphorus spin-coating. The frontside boron emitter was passivated either by applying a 10 nm deposited SiOX plasma-enhanced chemical vapor deposition (PECVD) or with a 10 nm grown thermal oxide. The anti-reflection coating layer formed a 60 nm thick SiNX layer. We show that energies less than 15 kV and doses around 5×10 15 cm −2 are appropriate to achieve open circuit voltage higher than 590 mV and efficiency around 16.7% on FZ-Si. The photovoltaic performances on ribbon silicon are so far limited by the bulk quality of the material and by the quality of the junction through the presence of silicon carbide precipitates at the surface. Nevertheless, we demonstrate that plasma immersion ion implantation is very promising for solar cell fabrication on ultrathin silicon wafers such as ribbons.

Solar‐grade boron emitters by BF3 plasma doping and role of the co‐implanted fluorine

“…This is not the case for boron emitters performed by beamline (with pure B + ions). It is to be noted that other reported works on BF 3 plasma doping applied on float zone and ribbon silicon substrates, for similar dose ranges, also showed implied V oc quite below 600 mV but with lower thermal budgets . Two hypotheses (possibly combined) could explain the low V oc phenomenon: A degradation of the bulk substrate lifetime (because of extra‐contamination, enhanced during the high thermal annealing, or because of another physicochemical phenomenon linked to the co‐implantation of fluorine), A passivation issue at the surface (residual defects zone and/or bad interfacial oxide).…”

Silicon Heterojunction Solar Cells Using AlOx and Plasma-Immersion Ion Implantation

“…Plasma immersion ion implantation (PIII) was used in this study to enhance performance [18][19][20]. The target received substantial negative pulse voltage, and plasma was formed by the RF power in the cavity.…”