Dislocation density reduction during impurity gettering in multicrystalline silicon

H. J. Choi, M. I. Bertoni, J. Hofstetter, D. P. Fenning, D. M. Powell, S. Castellanos, T. Buonassisi

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations

Abstract

Isothermal annealing above 1250 °C has been reported to reduce the dislocation density in multicrystalline silicon (mc-Si), presumably by pairwise dislocation annihilation. However, this high-temperature process may also cause significant impurity contamination, canceling out the positive effect of dislocation density reduction on cell performance. Here, efforts are made to annihilate dislocations in mc-Si in temperatures as low as 820 °C, with the assistance of an additional driving force to stimulate dislocation motion. A reduction of more than 60% in dislocation density is observed for mc-Si containing intermediate concentrations of certain metallic species after P gettering at 820 °C. While the precise mechanism remains in discussion, available evidence suggests that the net unidirectional flux of impurities in the presence of a gettering layer may cause dislocation motion, leading to dislocation density reduction. Analysis of minority carrier lifetime as a function of dislocation density suggests that lifetime improvements after P diffusion in these samples can be attributed to the combined effects of dislocation density reduction and impurity concentration reduction. These findings suggest there may be mechanisms to reduce dislocation densities at standard solar cell processing temperatures.

Original languageEnglish (US)
Title of host publication2012 IEEE 38th Photovoltaic Specialists Conference, PVSC 2012
PublisherInstitute of Electrical and Electronics Engineers Inc.
EditionPART 2
ISBN (Print)9781467328883
DOIs
StatePublished - 2012
Externally publishedYes
Event2012 IEEE 38th Photovoltaic Specialists Conference, PVSC 2012 - Austin, TX, United States
Duration: Jun 3 2012Jun 8 2012

Publication series

NameConference Record of the IEEE Photovoltaic Specialists Conference
NumberPART 2
ISSN (Print)0160-8371

Other

Other2012 IEEE 38th Photovoltaic Specialists Conference, PVSC 2012
CountryUnited States
CityAustin, TX
Period6/3/126/8/12

Keywords

  • Al gettering
  • P gettering
  • dislocation density
  • dislocation impurity interaction
  • multicrystalline silicon

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Industrial and Manufacturing Engineering
  • Electrical and Electronic Engineering

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    Choi, H. J., Bertoni, M. I., Hofstetter, J., Fenning, D. P., Powell, D. M., Castellanos, S., & Buonassisi, T. (2012). Dislocation density reduction during impurity gettering in multicrystalline silicon. In 2012 IEEE 38th Photovoltaic Specialists Conference, PVSC 2012 (PART 2 ed.). [2219851] (Conference Record of the IEEE Photovoltaic Specialists Conference; No. PART 2). Institute of Electrical and Electronics Engineers Inc.. https://doi.org/10.1109/pvsc-vol2.2012.6656733