ECN publication
Title:
SiN precipitate formation related to metal contamination of multicrystalline silicon for solar cells
 
Author(s):
 
Published by: Publication date:
ECN Solar Energy 6-9-2010
 
ECN report number: Document type:
ECN-M--10-015 Conference Paper
 
Number of pages: Full text:
4 Download PDF  

Presented at: 25th European Photovoltaic Solar Energy Conference and Exhibition - 5th World Conference on Photovoltaic Energy Conversion, Valencia, Spain, 6-10 september 2010.

Abstract:
Elongated filaments and periodically waved sheets were observed along the grain boundaries of etched multi-crystalline wafers from intentionally contaminated ingots. The filaments and sheets consist of silicon nitride, as was confirmed by Energy Dispersive X-ray analysis (EDX). The abundance of the SiN sheets and filaments increases with a higher concentration of metal impurities and, except for the absolute top and bottom, was not observed in the uncontaminated reference ingots. Solar cells made from filament regions of the ingot display strong FF losses due to the presence of shunts, depending on the level of metal contamination. The shunt patterns, observed using lock-in thermography, are correlated to the regions where the filaments are present.


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