Light Induced Degradation in Manufacturable Multi-crystalline Silicon Solar Cells
Damiani, Benjamin Mark
Hilali, Mohamed M.
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Traditional Czochralski grown Si solar cells are known to suffer from light induced degradation (LID) which adversely affects the minority carrier lifetime. Multi-crystalline Si has also been shown to show a similar degradation/recovery cycle after a phosphorus gettering step. In this paper, promising ribbon and cast multi-crystalline Si are examined for light induced degradation. High oxygen materials (≥10(18)cm(-3)) like dendritic web, Baysix Cz, and conventional Cz show similar degradation/recovery, HEM cast multi-crystalline with modest oxygen content (2.5x10(17)cm(-3)) shows small LID, and EFG and string ribbon silicon with low oxygen content (< 2.5x10(17)cm(-3)) show no LID. In addition light induced degradation is investigated at elevated temperatures. It is shown that bulk lifetime is degraded at 400 degrees C under tungsten halogen lamp illumination in a belt furnace suggesting that at 400 degrees C LID is greater than any annealing. At higher temperature belt processing under lamp (>400 degrees C) the net LID is partially reduced. On the other hand bulk lifetime is annealed in a conventional furnace at 400 degrees C with no lamp illumination.