Experimental evidence on removing copper and light-induced degradation from silicon by negative charge
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School of Electrical Engineering |
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Date
2014
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Mcode
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Language
en
Pages
3
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Applied Physics Letters, Vol. 105, Issue 18
Abstract
In addition to boron and oxygen, copper is also known to cause light-induced degradation (LID) in silicon. We have demonstrated previously that LID can be prevented by depositing negative corona charge onto the wafer surfaces. Positively charged interstitial copper ions are proposed to diffuse to the negatively charged surface and consequently empty the bulk of copper. In this study, copper out-diffusion was confirmed by chemical analysis of the near surface region of negatively/positively charged silicon wafer. Furthermore, LID was permanently removed by etching the copper-rich surface layer after negative charge deposition. These results demonstrate that (i) copper can be effectively removed from the bulk by negative charge, (ii) under illumination copper forms a recombination active defect in the bulk of the wafer causing severe light induced degradation.Description
Keywords
copper, silicon, light-induced degradation, LID, etching, surfaces, illumination, wafer, solar cells
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Citation
Boulfrad, Yacine & Lindroos, Jeanette & Wagner, Matthias & Wolny, Franziska & Yli-Koski, Marko & Savin, Hele. 2014. Experimental evidence on removing copper and light-induced degradation from silicon by negative charge. Applied Physics Letters. Vol. 105, Issue 18. 1077-3118 (electronic). DOI: 10.1063/1.4901533