Precipitated iron: a limit on gettering efficacy in multicrystalline silicon

Fenning, David P. and Hofstetter, Jasmin and Bertoni, Mariana I. and Coletti, Gianluca and Lai, B. and Cañizo Nadal, Carlos del and Buonassisi, Tonio (2013). Precipitated iron: a limit on gettering efficacy in multicrystalline silicon. "Journal of Applied Physics", v. 113 (n. 4); pp.. ISSN 0021-8979. https://doi.org/10.1063/1.4788800.

Description

Title: Precipitated iron: a limit on gettering efficacy in multicrystalline silicon
Author/s:
  • Fenning, David P.
  • Hofstetter, Jasmin
  • Bertoni, Mariana I.
  • Coletti, Gianluca
  • Lai, B.
  • Cañizo Nadal, Carlos del
  • Buonassisi, Tonio
Item Type: Article
Título de Revista/Publicación: Journal of Applied Physics
Date: January 2013
ISSN: 0021-8979
Volume: 113
Subjects:
Faculty: E.T.S.I. Telecomunicación (UPM)
Department: Electrónica Física
Creative Commons Licenses: Recognition - No derivative works - Non commercial

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Abstract

A phosphorus diffusion gettering model is used to examine the efficacy of a standard gettering process on interstitial and precipitated iron in multicrystalline silicon. The model predicts a large concentration of precipitated iron remaining after standard gettering for most as-grown iron distributions. Although changes in the precipitated iron distribution are predicted to be small, the simulated post-processing interstitial iron concentration is predicted to depend strongly on the as-grown distribution of precipitates, indicating that precipitates must be considered as internal sources of contamination during processing. To inform and validate the model, the iron distributions before and after a standard phosphorus diffusion step are studied in samples from the bottom, middle, and top of an intentionally Fe-contaminated laboratory ingot. A census of iron-silicide precipitates taken by synchrotron-based X-ray fluorescence microscopy confirms the presence of a high density of iron-silicide precipitates both before and after phosphorus diffusion. A comparable precipitated iron distribution was measured in a sister wafer after hydrogenation during a firing step. The similar distributions of precipitated iron seen after each step in the solar cell process confirm that the effect of standard gettering on precipitated iron is strongly limited as predicted by simulation. Good agreement between the experimental and simulated data supports the hypothesis that gettering kinetics is governed by not only the total iron concentration but also by the distribution of precipitated iron. Finally, future directions based on the modeling are suggested for the improvement of effective minority carrier lifetime in multicrystalline silicon solar cells.

More information

Item ID: 26093
DC Identifier: http://oa.upm.es/26093/
OAI Identifier: oai:oa.upm.es:26093
DOI: 10.1063/1.4788800
Official URL: http://scitation.aip.org/content/aip/journal/jap/113/4/10.1063/1.4788800
Deposited by: Memoria Investigacion
Deposited on: 24 May 2014 07:13
Last Modified: 22 Sep 2014 11:39
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