Finite- vs. infinite-source emitters in silicon photovoltaics: Effect on transition metal gettering

• Main Authors: Vahanissi, Ville (Author), Liu, Zhengjun (Author), Huang, Haibing (Author), Magana, Ernesto (Author), Khelifati, Nabil (Author), Husein, Sebastian (Author), Lai, Barry (Author), Bouhafs, Djoudi (Author), Laine, Hannu (Contributor), Morishige, Ashley Elizabeth (Contributor), Bertoni, Mariana I (Contributor), Buonassisi, Anthony (Contributor), Fenning, David P (Contributor), Savin, Hele Irene (Contributor)
• Other Authors: Massachusetts Institute of Technology. Department of Mechanical Engineering (Contributor)
• Format: Article
• Language: English
• Published: Institute of Electrical and Electronics Engineers (IEEE), 2018-11-19T14:27:49Z.
• Subjects: Article
• Online Access: Get fulltext

 Control of detrimental metal impurities is crucial to silicon solar cell performance. Traditional silicon solar cell emitters are diffused in an infinite-source regime and are known to cause strong point defect segregation towards the emitter and thus enhance bulk minority carrier diffusion length. With the advent of ion-implantation and chemical vapor deposition (CVD) glasses, finite-source diffused emitters are attracting interest. This contribution aims to increase their adoption by elucidating the dominant gettering mechanisms present in finite-source diffused emitters. Our findings indicate that infinite-source diffusion is critical for effective segregation gettering, but that high enough surface phosphorus concentration can activate segregation gettering via finite-source diffusion as well. In the case of ion-implanted emitters, the traditional segregation gettering may be considerably enhanced by impurity precipitation in the implanted layer.