Effect of low-temperature annealing on defect causing copper-related light-induced degradation in p-type silicon

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Journal Title
Journal ISSN
Volume Title
Conference article in proceedings
Date
2017
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Degree programme
Language
en
Pages
9
188-196
Series
7th International Conference on Silicon Photovoltaics, SiliconPV 2017, Volume 124, Energy Procedia
Abstract
Copper is a common impurity in photovoltaic silicon. While reported to precipitate instantly in n-type Si, copper causes light-induced degradation (Cu-LID) in p-type Si. Recently, partial recovery of Cu-LID was observed after only few minutes of dark annealing at 200°C. In this contribution, we investigate the effects of the dark anneal on Cu-LID-limited minority carrier lifetime both experimentally and by simulations. Surprisingly, after initial recovery, the dark anneal results in further degradation corresponding to a many-fold increase in recombination activity compared to the degraded state after illumination. This anneal-induced degradation can potentially cause additional losses in accidentally Cu-contaminated devices when exposed to elevated temperatures, for example during recovery and regeneration treatments of solar cells. Transient ion drift measurements confirmed that the anneal-induced degradation cannot be attributed to residual interstitial Cu after illumination. After hundreds of hours of annealing, the samples showed another recovery. To analyze these experimental results, a comparison to simulations is performed at the end of the paper.
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Keywords
Cu, LID, precipitate, recovery, silicon
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Citation
Vahlman, H, Haarahiltunen, A, Kwapil, W, Schön, J, Yli-Koski, M, Inglese, A, Modanese, C & Savin, H 2017, Effect of low-temperature annealing on defect causing copper-related light-induced degradation in p-type silicon . in 7th International Conference on Silicon Photovoltaics, SiliconPV 2017 . vol. 124, Energy Procedia, Elsevier BV, pp. 188-196, International Conference on Crystalline Silicon Photovoltaics, Freiburg, Germany, 03/04/2017 . https://doi.org/10.1016/j.egypro.2017.09.314