Title:	Lifetime Evolution during Regeneration in Boron-Doped Czochralski-Silicon
Author(s):	D.C. Walter, L. Helmich, D. Bredemeier, R. Falster, V.V. Voronkov, J. Schmidt
Keywords:	Regeneration, Czochralski Silicon, Boron-Oxygen Defect
Topic:	Silicon Cells
Subtopic:	Feedstock, Crystallisation, Wafering, Defect Engineering
Event:	35th European Photovoltaic Solar Energy Conference and Exhibition
Session:	2AV.1.29
Pages:	522 - 526
ISBN:	3-936338-50-7
Paper DOI:	10.4229/35thEUPVSEC20182018-2AV.1.29
Price:	0,00 EUR
Document(s):	paper

Abstract/Summary:

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We measure the evolution of the carrier lifetime in boron-doped Czochralski-grown silicon wafers for the first time in-situ during permanent deactivation of the boron-oxygen defect under the applied conditions, i.e. illumination with a halogen lamp at elevated temperatures. Applying illumination intensities ≥1 sun on standard 1.5 Ωcm p-type Cz-Si, the lifetime (measured at the regeneration temperature) changes only negligibly during this regeneration process. As expected, in this case, the time dependence of the defect concentration (measured at room temperature) follows a single-exponential decay function during regeneration. For light intensities << 1 sun on the same material, the lifetime shows a significant change during the regeneration conditions and the evolution of the defect concentration does no longer follow a single-exponential decay curve. In addition, on 0.5 Ωcm p-type Cz-Si we observe a non-exponential decay of the defect concentration for a regeneration treatment performed at 1 sun illumination intensity and a single-exponential decay for a higher illumination intensity of 2.9 suns. These observations are well compatible with a deactivation rate increasing proportionally with the excess carrier concentration.