Iron distribution in silicon after solar cell processing: Synchrotron analysis and predictive modeling

The evolution during silicon solar cell processing of performance-limiting iron impurities is investigated with synchrotron-based x-ray fluorescence microscopy. We find that during industrial phosphorus diffusion, bulk precipitate dissolution is incomplete in wafers with high metal content, specific...

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Bibliographic Details
Main Authors: Fenning, David P., Hofstetter, Jasmin, Bertoni, Mariana I., Hudelson, S., Rinio, M., Lelievre, J. F., Lai, Barry, del Canizo, C., Buonassisi, Tonio
Other Authors: Massachusetts Institute of Technology. Department of Mechanical Engineering
Format: Article
Language:en_US
Published: American Institute of Physics (AIP) 2013
Online Access:http://hdl.handle.net/1721.1/78005
https://orcid.org/0000-0002-4609-9312
https://orcid.org/0000-0001-8345-4937
Description
Summary:The evolution during silicon solar cell processing of performance-limiting iron impurities is investigated with synchrotron-based x-ray fluorescence microscopy. We find that during industrial phosphorus diffusion, bulk precipitate dissolution is incomplete in wafers with high metal content, specifically ingot border material. Postdiffusion low-temperature annealing is not found to alter appreciably the size or spatial distribution of FeSi[subscript 2] precipitates, although cell efficiency improves due to a decrease in iron interstitial concentration. Gettering simulations successfully model experiment results and suggest the efficacy of high- and low-temperature processing to reduce both precipitated and interstitial iron concentrations, respectively.