The effect of an electrical field on the radiation tolerance of float zone and magnetic Czochralski silicon particle detectors

The influence of an electrical field on the formation of defects in silicon particle detectors during particle irradiation was studied. Silicon pad detectors processed on Float Zone and Magnetic Czochralski silicon were irradiated with 7-MeV protons between the fluences of 5×1012 and 1.25×1013 protons/cm2. The irradiations were performed at 220 K, with half of the samples being kept under reverse bias voltage. The full depletion voltage of the detectors was extracted by capacitance-voltage (CV) measurements immediately after the irradiations. The samples were re-measured for CV and current-voltage (IV) characteristics after a 26-day storage period at 255 K and again after a further storage period of about two months at 273 K. The samples were finally studied by means of the transient current technique (TCT) with infrared (1060 nm) and red (670 nm) lasers. An explicit conclusion of the study is that the irradiation of the detectors with a simultaneously applied bias voltage reduces the introduction of the negative space charge and the current-related damage for both detector types.