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Simultaneous Boron Emitter Diffusion and Crystallization of TOPCon Layers via Rapid Vapour-Phase Direct Doping

: Drießen, M.; Richter, A.; Steinhauser, B.; Feldmann, F.; Polzin, J.-I.; Sahajad, F.; Ohnemus, M.; Weiss, C.; Benick, J.; Janz, S.

Volltext urn:nbn:de:0011-n-6181652 (418 KByte PDF)
MD5 Fingerprint: d74ca63ecdcadb91810111f78c88076a
Erstellt am: 16.12.2020

Pearsall, Nicola (Editor):
37th European Photovoltaic Solar Energy Conference and Exhibition, EU PVSEC 2020 : 07-11 September 2020, Online Conference
München: WIP, 2020
ISBN: 3-936338-73-6
European Photovoltaic Solar Energy Conference and Exhibition (EU PVSEC) <37, 2020, Online>
Konferenzbeitrag, Elektronische Publikation
Fraunhofer ISE ()
Photovoltaik; Silicium-Photovoltaik; Dotierung und Diffusion; Oberflächen: Konditionierung; Passivierung; Lichteinfang

The alternative boron emitter diffusion process rapid vapour phase direct doping (B-RVD) is applied to n-type silicon wafers with tunnel oxide passivated contact (TOPCon) rear sides. A variation of the B-RVD process parameters led to an increase of the emitter depth and less pronounced increase of the surface concentration with increasing process temperature, time and B2H6 concentration. For the first time, a simultaneous crystallization of the phosphorus doped amorphous silicon a-Si(n) layer in the TOPCon layer during the B-RVD process is investigated. For this, the B-RVD process with the lowest tested process temperature of 900 °C and with the lowest determined emitter saturation current density J0e of 13 fA/cm2 and the highest bulk lifetime of > 6500 µs was chosen. The transformation of a-Si(n) to poly-Si within this combined process is demonstrated. Directly after the RVD process, TOPCon layers are already very well passivating the surfaces. An additional hydrogenation step leads to further improvement. On a solar cell precursor fabricated with simultaneous a-Si(n) crystallization on the rear side and BRVD emitter diffusion on the front side promising results with an iVOC of ≥ 700 mV and an implied fill factor (iFF) of 84.7 % were measured.