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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AbstractRadiation <strong>damage</strong> <strong>of</strong> the <strong>silicon</strong> bulk will play an important role <strong>in</strong> the vertex <strong>detectors</strong><strong>in</strong> the future experiments at LHC. To study its macroscopic eects, <strong>high</strong> resistivityp + -n-n + diodes were irradiated with neutrons at the TRIGA research reactor <strong>of</strong> JozefStefan Institute <strong>in</strong> Ljubljana. Ir<strong>radiation</strong> uences were <strong>in</strong> the range from 10 13 to 2.510 14/cm 2 <strong>of</strong> equivalent 1 MeV neutrons. Development <strong>of</strong> eective dop<strong>in</strong>g concentration andreverse current dur<strong>in</strong>g and after ir<strong>radiation</strong>s was studied under controlled conditions (bias,temperature).Long term anneal<strong>in</strong>g <strong>of</strong> eective dop<strong>in</strong>g concentration was studied to determ<strong>in</strong>e thedynamics <strong>of</strong> the process responsible. Results obta<strong>in</strong>ed from a set <strong>of</strong> unbiased diodes keptat 20 Cgave conclusive evidence that, at least dur<strong>in</strong>g the <strong>in</strong>itial stage, time developmentcan be described by a rst order process.Flux dependence <strong>of</strong> defect creation has been checked <strong>in</strong> the ux range from 210 8 to 510 15 n/cm 2 s. No signicant dierence among the samples was observed <strong>in</strong> any <strong>of</strong>thestudied properties.Inuence <strong>of</strong> bias voltage on defect development was discovered. Fully biased sampleswere found to have about a factor 2 <strong>high</strong>er values <strong>of</strong> N eff after benecial anneal<strong>in</strong>g. Afterremoval <strong>of</strong> bias, the dierence anneals out exponentially with two time constants <strong>of</strong> about40h and 6weeks at 20 C. No <strong>in</strong>uence <strong>of</strong> bias voltage on reverse current was observed.Keywords: <strong>silicon</strong> <strong>detectors</strong>, <strong>radiation</strong> hardness, neutron ir<strong>radiation</strong>, LHCPACS 29.40.Gx, 29.40.Wk