The deteriorated area of the multicrystalline silicon (mc‐Si) ingots grown by directional solidification, commonly known as the Red Zone, is usually removed before wafering. This area, characterized by poor minority carrier lifetime, is located on the sides, at the top, and the bottom of the mc‐Si ingots. In this study, the effect of internal gettering by oxygen precipitates and structural defects has been investigated on the bottom zone of a mc‐Si ingot. Nucleation and growth of oxygen precipitates as well as low temperature annealing were studied. Photoluminescence imaging, lifetime mapping, and interstitial iron measurements performed by μ‐PCD reveal a considerable reduction of the bottom Red Zone. An improvement of lifetime from below 1 µs to about 20 µs and a reduction of interstitial iron concentration from 1.32 × 10 13 at/cm 3 to 8.4 × 10 10 at/cm 3 are demonstrated in this paper. Copyright © 2013 John Wiley & Sons, Ltd. The deteriorated area (Red Zone) of the mc‐Si ingots grown by directional solidification is located on the sides, at the top, and the bottom of the ingots. In this study, several internal gettering approaches have been investigated on the bottom Red Zone of a mc‐Si ingot. Considerable reduction of the bottom Red Zone was revealed. An improvement of lifetime from below 1 μs to about 20 μs and a reduction of Fe i concentration from 1.32 × 10 13 at/cm 3 to 8.4 × 10 10 at/cm 3 are demonstrated.
Enhanced performance in the deteriorated area of multicrystalline silicon wafers by internal gettering
Progress in photovoltaics ; 23 , 1
2015
Article (Journal)
English
BKL: | 53.36 Energiedirektumwandler, elektrische Energiespeicher |
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