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HL: Halbleiterphysik
HL 32: Photovoltaic
HL 32.18: Talk
Wednesday, March 29, 2006, 19:00–19:15, BEY 118
Investigation of the correlation between charge carrier lifetime of multicrystalline silicon raw wafer and solar cell efficiency — •Kevin Lauer1, Stefan Dauwe1, and Jan Lossen2 — 1SolarZentrum Erfurt, CIS Institut für Mikrosensorik, Konrad-Zuse-Str. 14, D-99099 Erfurt — 2ErSol Solar Energy AG, Wilhelm-Wolff-Str. 23 D-99099 Erfurt
The correlation between multicrystalline silicon raw wafers and solar cell efficiency depends both on wafer quality and on the solar cell process. It is of large scientific and economic interest to understand these influencing factors in order to predict the solar cell efficiency.
In this work the electrical properties of multicrystalline silicon wafers are characterized by minority carrier lifetime measurements. We measured the lifetime of adjacent wafers from one column before emitter diffusion. Subseqeuntly, these wafers were processed to solar cells. As expected, a higher carrier lifetime of a raw wafer results in a higher solar cell efficiency. However, the position of the wafer within the column needs to be known additionally for a more precise prediction of the solar cell efficiency. We attribute this to the defect distribution across the column.
The content of one of the dominating defects, interstitial iron, was measured before and after diffusion. The standard method based on carrier lifetime measurements before and after light soaking was extended to improve the measurement sensitivity.