January 1, 2006
Conference Paper

Transition metals in photovoltaic-grade ingot-cast multicrystalline silicon: Assessing the role of impurities in silicon nitride crucible lining material

Abstract

We assess the contamination potential of crucibles used during directionally-solidified multicrystalline silicon (mc-Si) ingot casting for cost-effective solar cell wafer production. Highly-sensitive, synchrotron-based analytical microprobe techniques were used to study the distributions, sizes, elemental natures, and chemical states of impurity-rich particles in alpha-Si3N4 powder representative of what is used to coat the inside of mc-Si ingot-casting crucibles, as well as the as-grown cast mc-Si material. Correlations between the elemental species, chemical states, particle sizes, relative concentrations, and locations of impurities (e.g. Fe, Ti, Ca, Zn, Ni, Cu, N, C) concomitant in alpha-Si3N4 and as-grown mc-Si lead us to conclude that alpha-Si3N4 could be a significant source of contaminants during the ingot-casting mc-Si growth process.

Revised: December 5, 2007 | Published: January 1, 2006

Citation

Buonassisi T., A.A. Istratov, M.D. Pickett, J.P. Rakotoniaina, O. Breitenstein, M.A. Marcus, and S.M. Heald, et al. 2006. "Transition metals in photovoltaic-grade ingot-cast multicrystalline silicon: Assessing the role of impurities in silicon nitride crucible lining material." In 16th American Conference on Crystal Growth and Epitaxy, (ACCGE 16) published in Journal of Crystal Growth, 287, 402-407. Amsterdam:Elsevier. PNNL-SA-46236. doi:doi:10.1016/j.jcrysgro.2005.11.053