ECN publication
Title:
Iron detection in crystalline silicon by carrier lifetime measurements for arbitrary injection and doping
 
Author(s):
 
Published by: Publication date:
ECN Solar Energy 1-2-2004
 
ECN report number: Document type:
ECN-RX--04-010 Article (scientific)
 
Number of pages:
8  

Published in: Journal of Applied Physics (American Institute of Physics), , 2004, Vol.95, p.1021-1028.

Abstract:
An existing technique for accurate measurement of iron in silicon, whichwas previously restricted to low-injection and a narrow doping range, has been extended to arbitrary injection and doping levels. This allows contact-less lifetime measurement techniques to be used for very sensitive and rapid iron detection under a wide range of conditions. In addition, a new, easily measured and unambiguous ?fingerprint? of iron in silicon is identified. It is based on the invariant nature of the excess carrier density at which the injection-dependent lifetime curves, measured before and after iron-boron pair dissociation, cross over. This characteristic crossover point lies in the narrow range of 1.4 to 2.0x1014cm-3, provided only that the boron concentration is below 5x1016cm-3. To demonstrate the value of these new techniques, they have been applied to photovoltaic-grade cast multicrystalline silicon wafers.


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