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Description
Nitrogen and oxygen enriched FZ silicon was investigated with respect to the radiation hardness under electron irradiation. P-in-n pad detectors were fabricated on four groups of FZ silicon wafers (FZ, NFZ, DOFZ and DOPFZ). Group NFZ was enriched with nitrogen during crystal growth. The DOFZ and DOPFZ groups were enriched with oxygen by oxygen indiffusion during prolonged annealing. The DOPFZ group received an additional oxygen precipitation treatment. Nitrogen and oxygen concentrations were measured by low temperature FTIR spectroscopy. The p-in-n diodes were characterized by IV measurements prior and after irradiation. Additionally, the excess charge carrier lifetime was determined by measuring the open circuit voltage decay prior and after irradiation. It was found that for all types of enrichment the irradiation induced defect density is reduced in comparison to the reference FZ silicon group. Strongest reduction of the induced defect density was found for the DOPFZ group.
