Effect of impurities on the minority carrier lifetime of silicon made by the metallurgical route
Holt, A.
,
Enebakk, E.
,
Soiland, A.-K.
European Photovoltaic Solar Energy Conference, 22, Milano, 2007-09-03--09-07
- Publ. year
- 2007
- Publ. type
- paper
- Abstract
- The objective of this study has been to investigate the relationship between the impurity level and the minority carrier lifetime of solar grade silicon made by the metallurgical route by Elkem Solar (ES). The wafers have been characterised by microwave photo conductance decay (μ-PCD), FeB-pair splitting and neutron activation analyses (NAA). The results of the minority carrier lifetime measurements show higher minority carrier lifetime of ES-wafers compared with results from wafers based on poly silicon material. A P-gettering processes has successfully been introduced, showing an average improvement by a factor larger than two. At [Fe] of about 1013 atoms/cm3 clustering starts to form in the red zone near the border of edge wafers. It is assumed that these clusters are electrically less active. This is supported by the increase of lifetime near the edge in the red zone. Most likely iron silicide clusters are formed.
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