Significant minority carrier lifetime improvement in red edge zone in n-type multicrystalline silicon

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© 2013 Elsevier BV. This is the post print version of the following article: Vähänissi, Ville & Yli-Koski, Marko & Haarahiltunen, Antti & Talvitie, Heli & Bao, Yameng & Savin, Hele. 2013. Significant minority carrier lifetime improvement in red edge zone in n-type multicrystalline silicon. Solar Energy Materials and Solar Cells. Volume 114. 54-58. ISSN 0927-0248 (printed). DOI: 10.1016/j.solmat.2013.02.026, which has been published in final form at http://www.sciencedirect.com/science/article/pii/S0927024813000974.

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Journal Title

Journal ISSN

Volume Title

School of Electrical Engineering | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

Date

2013

Major/Subject

Mcode

Degree programme

Language

en

Pages

54-58

Series

Solar Energy Materials and Solar Cells, Volume 114

Abstract

We have carried out experiments on both boron diffusion gettering (BDG) and phosphorus diffusion gettering (PDG) in n-type multicrystalline silicon. We have focused our research on the highly contaminated edge areas of the silicon ingot often referred to as the red zone. Due to poor carrier lifetime attributed to these areas, they induce a significant material loss in solar cell manufacturing. In our experiments, the red zone was found to disappear after a specific BDG treatment and a lifetime improvement from 5 μs up to 670 μs was achieved. Outside the red zone, lifetimes even up to 850 μs were measured after gettering. Against the common hypothesis, we found higher dopant in-diffusion temperature beneficial both for the red zone and the good grains making BDG more efficient than PDG. To explain the results we suggest that high temperature leads to more complete dissolution of metal precipitates, which enhances the diffusion gettering to the emitter.

Description

Keywords

n-type mc-Si, lifetime, gettering, red zone

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Citation

Vähänissi, Ville & Yli-Koski, Marko & Haarahiltunen, Antti & Talvitie, Heli & Bao, Yameng & Savin, Hele. 2013. Significant minority carrier lifetime improvement in red edge zone in n-type multicrystalline silicon. Solar Energy Materials and Solar Cells. Volume 114. 54-58. ISSN 0927-0248 (printed). DOI: 10.1016/j.solmat.2013.02.026.