Abstract
Following the observation of grown-in bulk defects limiting the lifetime of FZ silicon by Nicholas Grant and Fiacre Rougieux we have developed a thermal pre-treatment to mitigate the impact of such defects on photovoltaic research. In a joined effort with multiple groups we have demonstrated that the treatment increses the bulk lifetime significantly. The combination of the pre-treatment with state-of-the-art surface passivation layers allows for the demonstration of world record lifetimes on a broad range of samples. Pre-treated FZ silicon can be used for the great reference material the community has long assumed it to be. We demonstrate this by showing that the infamous LeTID effect can also be found in FZ silicon. This provides valuable insights concerning the nature of the underlying defect.
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Brief Bio
Tim Niewelt studied materials science at the technical university of Darmstadt and joined Fraunhofer ISE in 2011. His work focuses on recombination-active defects in monocrystalline silicon and their characterisation via charge carrier lifetime measurements. He finished his PhD in 2017 and is now working as a postdoc in the laboratory for photovoltaic energy conversion at the University of Freiburg and in the material characterisation department of Fraunhofer ISE.
