Imaging of Metal Impurities in Silicon by Luminescence Spectroscopy and Synchrotron Techniques

摘要

Metals are detrimental to silicon solar cells in two ways: (i) they typically introduce defect levels in the bandgap, leading to enhanced carrier recombination and thus to lower voltage in solar cells; and (ii) they may, in the form of precipitates, contribute to the formation of shunts and reverse breakdown sites. This paper provides a review on techniques to access the spatial distribution of recombination sites for multicrystalline silicon. Methods to detect metal precipitates as well as, in the case of iron, dissolved point defects are presented. These methods are applied to clarify the distribution of iron after high-temperature processes and the identification of breakdown sites.