Study of radiation damage in silicon detectors for high ... - F9
Study of radiation damage in silicon detectors for high ... - F9
Study of radiation damage in silicon detectors for high ... - F9
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74 4. Time Development <strong>of</strong> DefectsLower full depletion voltages <strong>for</strong> MESA processed samples as compared to planarones have also been reported by G. Casse et al. [48]. They observed systematically better<strong>radiation</strong> hardness <strong>of</strong> MESA samples as compared to planar ones. The dierence shows asan about factor <strong>of</strong> two lower <strong>in</strong>troduction rate <strong>of</strong> acceptor-like defects, lower <strong>in</strong>troductionrate <strong>of</strong> reverse anneal<strong>in</strong>g defects and lower <strong>damage</strong> constant. Those eects are howevernot <strong>in</strong>duced by <strong>in</strong>creased oxygen concentration only, s<strong>in</strong>ce results on oxygenated planarsamples (up to several 10 17 cm ;3 ) show no decrease <strong>in</strong> FDV or value as compared tonon-oxygenated planar samples [48]. Agreement <strong>of</strong> FDV after ir<strong>radiation</strong> <strong>for</strong> standardand oxygenated materials was also reported by L. Beattie et al. [49], while B. Dezillie etal. [32] reports better <strong>radiation</strong> resistivity <strong>of</strong> MESA samples and M. Moll et al. [50] <strong>for</strong>Czochralski samples, both hav<strong>in</strong>g an <strong>in</strong>creased oxygen concentration (order <strong>of</strong> 10 18 cm ;3 ).4.4 Anneal<strong>in</strong>g <strong>of</strong> Reverse CurrentAs with N eff , the time development <strong>of</strong> bulk generation current was studied <strong>in</strong> two parts:fast anneal<strong>in</strong>g at various temperatures dur<strong>in</strong>g the rst week after ir<strong>radiation</strong> and longterm anneal<strong>in</strong>g at 60 C to accelerate time development.4.4.1 Fast Anneal<strong>in</strong>gSample T 0 0 1 1 2 2[ C] [10 ;17 A/cm] [10 ;17 A/cm] [h] [10 ;17 A/cm] [h]D3 15 C 4.6 2.0 4.2 1.9 55D1 15 C 4.1 1.2 15. 1.4 180B3 0 C 4.1 1.2 9.7 1.1 220K0 5 C 5.4 14. 1.4 2.5 20K3 5 C 5.1 7.4 2.2 1.9 38Table 4.9: List <strong>of</strong> samples and ir<strong>radiation</strong> temperatures with values <strong>of</strong> the t parametersaccord<strong>in</strong>g to eq. 4.11. For easier comparison between samples and with other authors, values <strong>of</strong>the parameter are normalised to 20 C.Fast anneal<strong>in</strong>g <strong>of</strong> reverse current was studied on samples D3, D1, B3, K0 and K3.Their ir<strong>radiation</strong> conditions are given <strong>in</strong> tables 4.1 and 4.3. The rest <strong>of</strong> the diodes had noguard r<strong>in</strong>g structures, guard r<strong>in</strong>gs were not connectable or had some other problems thatprevented reliable determ<strong>in</strong>ation <strong>of</strong> the bulk current.As with N eff , short term anneal<strong>in</strong>g can be tted with a constant part and two