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Title:
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Impact of iron and molybdenum in mono and multicrystalline float-zon silicon solar cells
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Author(s):
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Coletti, G.; Geerligs, L.J.; Manshanden, P.; Swanson, C.; Riepe, S.; Warta, W.; Arumughan, J.; Kopecek, R.
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Published by:
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Publication date:
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ECN
Solar Energy
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12-6-2007
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ECN report number:
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Document type:
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ECN-W--07-023
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Article (scientific)
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Number of pages:
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6
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Published in: Solid State Phenomena (), , 2007, Vol.published online June 13, p.-.
Abstract:
This paper investigates the impact of iron (Fe) and molybdenum (Mo) when they are introduced in the feedstock for Float-Zone (FZ) silicon (Si) growth. Neutron Activation Analysis shows that the segregation coefficient is in agreement with literature values. Lifetime maps on monocrystalline wafers show a uniform lifetime which decreases with the increase of contamination levels. Multicrystalline wafers show low lifetime areas, corresponding to grain boundaries and highly dislocated areas, which are independent from the contamination levels. Intra grain areas have a higher lifetime which changes with the contamination levels. In multicrystalline wafers the lowest level of Fe introduced (1012 atm/cm3) has hardly any influence, whereas in the Mo-contaminated samples the impact is visible from the first level (1011 atm/cm3). In monocrystalline wafers the diffusion length is reduced already at the first contamination level of Fe. However this is barely visible in the monocrystalline cell performance because the diffusion length is higher than the solar cell thickness.
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