A. Litovchenko

Bulk Radiation Damage Induced in Thin Epitaxial Silicon Detectors by 24 GeV Protons

Radiation hardness of silicon detectors based on thin epitaxial layer for the LHC upgrade was studied. No type inversion was observed after irradiation by 24 GeV protons in the fluence range (1.5–10)⋅1015 cm–2 due to overcompensating donor generation. After long-term annealing highly irradiated devices show decrease of effective doping concentration and then undergo type inversion. All mentioned means that thin epitaxial devices might be used for innermost layers of vertex detectors and need moderate cooling during beam off time. Properly chosen scenario might help to restore their working characteristics.

Lithium ion irradiation effects on diodes manufactured on epitaxial silicon

Diodes manufactured on a thin and highly doped epitaxial silicon layer grown on a Czochralski silicon substrate have been irradiated by high-energy Lithium ions in order to investigate the effects of high bulk damage levels in such devices. This information is useful for possible developments of pixel detectors in future very high luminosity colliders because these new devices present superior radiation hardness than nowadays silicon detectors. The leakage current density increase, the variation of the depletion voltage and their annealing characteristics, as well as the charge collection properties of these new devices are presented and discussed in this study.

Radiation hardness of silicon diodes for high energy physics applications

Oxygenated and standard (not oxygenated) silicon diodes processed by CNM and IRST have been irradiated by 27 MeV protons and compared with standard devices from ST Microelectronics. As expected the leakage current density increase rate (/spl alpha/) and its annealing do not show any significant dependence on the starting material, oxygenation and/or processing of the considered devices. On the contrary, oxygenation improves the radiation hardness by decreasing the acceptor introduction rate (/spl beta/) and mitigating the depletion voltage (V/sub dep/) increase, with the /spl beta/ parameter depending also on starting material and/or effects related to device processing for standard diodes. Finally these results are included in a general review on the state of the art for silicon detector radiation hardening, confirming the good performance of the considered technologies.