Transition Metal Impurities in Silicon Nitride (Si3N4) Coating for Solar Silica Crucible Preparation for Silicon Crystallization

Autor: Chettat, Y., Boumaour, M., Senouci, S., Salhi, M., Slamene, H., Hamidatou, L., Benmounah, A.
Jazyk: angličtina
Rok vydání: 2013
Předmět:
DOI: 10.4229/28theupvsec2013-2bv.3.41
Popis: 28th European Photovoltaic Solar Energy Conference and Exhibition; 1465-1469
In this work we have used an advanced high sensitivity and multi elementary analytical technique such Neutron Activation Analyses (NAA) in attempt to determine exactly which metallic impurities of the above mentioned elements, and with which concentrations, they are present in four different origin silicon nitride coating powders, two different origin organic binders (METHOCEL A15LV) and an old standard solar fused silica crucible for crucible coating preparation for directional solidification of Multicrystalline (mc-Si). The obtained results show that the silicon nitride coating powder from supplier A is heavily contaminated, the dominant impurities are: Ca (3400 ppmw), Na (200 ppmw), (Fe (450 ppmw) and Co (51 ppmw), and that silicon nitride from coating powder supplier B is free Fe at least above detection limit of NAA, the dominants impurity in this coating variety is W (49 ppmw), and Na (30 ppmw); Therefore, we could consider it is cleaner than silicon nitride from supplier A and that it is more suitable for crucible coating preparation comparing with coating from supplier A. The NAA analyses show also that the two organic binders from supplier A and B are somewhat contaminated by Fe (12 ppmw) and Cr (10 ppmw), Zn (1,2 ppmw), it revealed that METHOCEL A is free of Na, and that METHOCEL B is heavily contaminated by Na (1800 ppmw), some ultra traces of metallic impurities were also detected, La, Sc, Sb, and Ce which have a negligible contribution in coating mixture contamination. The results of the analyses of the silica crucible monitor that this material is heavily contaminated by Fe (121 ppmw) Cr, Ca (185 ppmw), Na (62 ppmw), K (62 ppmw), and Zr (28 ppmw), and that the sintering coating prior and during crystallization lead to an increase in the concentration of iron in the coating material which is maybe due to diffusion from silica crucible.
Databáze: OpenAIRE
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