Blistering in ALD Al₂O₃ passivation layers as rear contacting for local Al BSF Si solar cells

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• 作者：B. Vermang^a ; ^b ; ^{Bart.Vermang@imec.be} ; H. Goverde^c ; A. Uruena^a ; ^b ; A. Lorenz^a ; E. Cornagliotti^a ; A. Rothschild^a ; J. John^a ; J. Poortmans^a ; ^b ; R. Mertens^a ; ^b
• 关键词：Si ; PERC ; Local Al BSF ; Surface passivation ; Atomic layer deposition ; Al2O3
• 刊名：Solar Energy Materials and Solar Cells
• 出版年：2012
• 期刊代码：81_09270248
• 类别：ce
• 出版时间：June, 2012
• 卷：101
• 期：Complete
• 页码：204-209
• 文件大小：1411 K

摘要

Random Al back surface field (BSF) p-type Si solar cells are presented, where a stack of Al₂O₃ and SiN_x is used as rear surface passivation layer containing blisters. It is shown that no additional contact opening step is needed, since during co-firing local Al BSFs are induced at the location of these blisters. The best fill factors and short circuit currents are obtained in the case of (i) a hydrophobic pre-passivation cleaning, since it leads to a small density of larger blisters, and (ii) 10 nm of Al₂O₃, where the blistering size still increases during firing thanks to additional out-gassing. There is an apparent gain in Jsc and Voc of, respectively, 1.3 mA/cm² and 5 mV for the best random Al BSF cells compared to full Al BSF reference cells, because of better rear internal reflection and rear surface passivation.