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Excellent surface passivation quality using industrial-scale direct-plasma TOPCon deposition technology

: Steinhauser, B.; Polzin, J.-I.; Feldmann, F.; Hermle, M.; Glunz, S.W.


Solar RRL 2 (2018), Nr.7, Art. 1800068, 5 S.
ISSN: 2367-198X
Fraunhofer ISE ()
Photovoltaik; Silicium-Photovoltaik; Oberflächen: Konditionierung; Passivierung; Lichteinfang; Kontaktierung und Strukturierung; contact; passivation

Passivating contacts based on a thin SiOx layer and a doped Si layer (TOPCon) are an appealing choice for pushing the efficiency of Si solar cells. One way to deposit the doped Si layer is to utilize radio‐frequency direct plasma‐enhanced chemical vapor deposition as commonly used in industry for the deposition of silicon nitride. However, due to the low operating frequency in the kHz range, there are concerns that ion bombardment might damage the thin SiOx layer and thus prevent suitable surface passivation. We demonstrate that this is not the case. Instead, the application of these layers on c‐Si results in excellent surface passivation. Minority carrier lifetimes exceeding the intrinsic bulk limit predicted by current models on 1 Ω cm n‐type were observed, out‐performing the reference layers. The excellent surface passivation results in an implied VOC of above 735 mV and an implied FF of almost 88% on 200 µm thick n‐type c‐Si. Furthermore, a lifetime test on 100 Ω cm n‐type c‐Si revealed an extraordinary lifetime of 190 ms (Δn = 1 × 1014 cm−3).