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Phosphorus gettering of iron by screen-printed emitters in monocrystalline Czochralski silicon wafers

Authors


Correspondence: Tobias M. Pletzer, Institute of Semiconductor Electronics, RWTH Aachen University, Sommerfeldstr. 24, D-52074 Aachen, Germany.

E-mail: pletzer@iht.rwth-aachen.de

ABSTRACT

In this paper, we demonstrate single-sided screen-printed emitters in thin monocrystalline Czochralski silicon (Cz-Si) wafers with an improved gettering of iron compared with conventional double-sided POCl3 emitters. The phosphorus dopant pastes used have to be chosen carefully to provide a sufficiently low emitter sheet resistance and to avoid iron contamination. The iron concentration is determined in a non-destructive way from the minority carrier lifetime obtained by quasi-steady-state photoconductance measurements, down to levels not yet demonstrated for screen-printed emitters. In addition, the well-known metastable boron–oxygen complexes in Cz-Si have been transferred into a stable state by light-induced degradation prior to these measurements. Copyright © 2012 John Wiley & Sons, Ltd.

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