Silicon diode radiation hardening for high energy physics detectors

We summarize in a general review all the studies performed by our group in the last years in the field of radiation hardening of silicon detectors for High Energy Physics experiments. Test structures (silicon p–i–n diodes) were irradiated by 16 MeV, 27 MeV, 34 MeV and 24 GeV protons, and by fast neutrons from a nuclear reactor and from the 9Be(d,n)10B nuclear reaction. We will show that after proton irradiation the substrate oxygenation mitigates the depletion voltage increase rate β, which nevertheless presents a wide range of values if standard and oxygenated devices processed by different manufacturers are considered, pointing out that besides oxygenation, processing affects the diode radiation hardness in the case of proton irradiation. After neutron irradiation though the oxygen mitigating effect is strongly suppressed, nonetheless the β dependence on the particular process can be important.