String Ribbon Silicon Solar Cells with 17.8% Efficiency
Date
2003-05Author
Kim, Dong Seop
Gabor, A. M.
Yelundur, Vijay
Upadhyaya, A. D.
Meemongkolkiat, Vichai
Rohatgi, Ajeet
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We have fabricated 4 cm(2) cells on String Ribbon Si wafers with efficiencies of 17.8% using a combination of laboratory and industrial processes. These are the most
efficient String Ribbon devices made to date,
demonstrating the high quality of the processed silicon and the future potential for industrial String Ribbon cells. Cofiring
PECVD (Plasma Enhanced Chemical Vapor
Deposition) silicon nitride (SiN(x)) and Al was used to boost the minority carrier lifetime of bulk Si. Photolithography front contacts were used to achieve low shading losses and low contact resistance with a good blue response. The firing temperature and time were studied with respect to the trade-off between hydrogen retention
and aluminum back surface field (Al-BSF) formation. Bulk defect hydrogenation and deep Al-BSF formation took place in a very short time (~1 sec) at temperatures
higher than 740 degrees C.