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Explanation of potential-induced degradation of the shunting type by Na decoration of stacking faults in Si solar cells

 
: Naumann, V.; Lausch, D.; Hähnel, A.; Bauer, J.; Breitenstein, O.; Graff, A.; Werner, M.; Swatek, S.; Großer, S.; Bagdahn, J.; Hagendorf, C.

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Solar energy materials and solar cells 120 (2014), Part A, pp.383-389
ISSN: 0927-0248
English
Journal Article
Fraunhofer IWM ( IMWS) ()
Fraunhofer CSP ()
potential-induced degradation; solar cells; crystals; silicon; stacking faults; sodium

Abstract
Crystalline Si solar cells that exhibit potential-induced degradation of the shunting type (PID-s) are investigated on a microstructural level. Cell pieces with PID-shunts are imaged by SEM using the EBIC technique in order to investigate PID-s positions with high lateral resolution. ToF-SIMS depth profiles reveal Na accumulation localized at these shunt positions. Subsequently, cross-sectional FIB-lamellas of individual PID-shunts have been prepared. TEM is applied to a number of PID-s defects. TEM/EDX measurements reveal that stacking faults crossing the p-n junction are decorated with Na causing PID-s. These defects are further characterized by high resolution STEM methods down to the atomic scale. A model for the shunting mechanism in PID-s affected solar cells is developed. The results are discussed with respect to different shunting mechanisms.

: http://publica.fraunhofer.de/documents/N-254674.html