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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5. Dose Rate Dependence 85Figure 5.4: Reverse anneal<strong>in</strong>g constant k Y 2versus ir<strong>radiation</strong> ux.errors on dosimetry. SA and P0 samples also have a larger error on FDV at late stages <strong>of</strong>reverse anneal<strong>in</strong>g. Its source is extrapolation <strong>of</strong> C ;2 versus Vcurve to the plateau value.This was necessary because <strong>of</strong> breakdown below full depletion voltage.5.3 Results on Reverse Current<strong>Study</strong> <strong>of</strong> the leakage current could un<strong>for</strong>tunately not be per<strong>for</strong>med on the full range <strong>of</strong> doserates. The reason were problems with guard r<strong>in</strong>g connections that occurred with samplesSA and P0. With guard r<strong>in</strong>gs not connected it was not possible to separate the bulkgeneration current from surface current generated on the edge. S<strong>in</strong>ce its contribution canbe much larger than the bulk generation current (see g. 3.13), those samples are useless<strong>for</strong> comparisons <strong>of</strong> the reverse current. Thus only samples K0, K1 and K3, irradiatedwith neutron uxes <strong>of</strong> 2:310 12 n/cm 2 s, 4:210 11 n/cm 2 sand2:110 9 n/cm 2 s are shown <strong>in</strong>gure 5.5. The reverse currents were tted accord<strong>in</strong>g to eq. 4.12 and results are given <strong>in</strong>table 5.3. Some measured po<strong>in</strong>ts with bad guard r<strong>in</strong>g connection <strong>for</strong> sample K1 on thatgure <strong>in</strong>dicate the variability <strong>of</strong>thesurface current contribution.Though one can notice some dierence among the samples it is attributed to themeasurement error. It is also not correlated with the ir<strong>radiation</strong> ux.