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Title:
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Hydrogen kinetics in crystalline silicon - PECVD SiN studies in mc and Cz silicon
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Author(s):
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Published by:
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Publication date:
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ECN
Solar Energy
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1-6-2005
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ECN report number:
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Document type:
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ECN-RX--05-018
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Conference Paper
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Number of pages:
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Full text:
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4
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Download PDF
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Presented at: 20th European Photovoltaic Solar Energy Conference and Exhibition, Barcelona, Spain, 6-10 juni 2005.
Abstract:
Trapping of hydrogen during diffusion in silicon due to impurities and/or
other defects is a well known
fact. Using SIMS we can demonstrate that high amounts of oxygen can
significantly slow down diffusion of
deuterium originating from PECVD SiN layers after a firing step (NH
3 exchanged by ND3) in mc RGS
Si. The
slowed down diffusion results in unwanted longer passivation times and
lower carrier lifetimes during solar cell
processing. Experiments using Cz Si samples differing in oxygen content
are presented as well. High temperature
annealing steps generate O-precipitates of defined size and concentration,
and more pronounced trapping of
deuterium appears for higher oxygen concentration. Even more trapping
can be detected when O-precipitates are
generated, with the highest deuterium concentrations for large precipitates.
An O-depleted region near the surface is
mirrored by lower deuterium concentrations, proving the link between
enhanced trapping when oxygen is present.
The overall amount of D-atoms incorporated into the Si bulk after firing
can be measured to about 1
A1014 cm-2.
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