Degradation of high-resistivity float zone and magnetic Czochralski n-type silicon detectors subjected to 2-MeV electron irradiation

Particle-tracking detectors made on high-resistivity (HR) float zone (FZ) silicon are widely used in high-energy physics experiments. It is known that the incorporation of oxygen in the FZ Si can lead to some improvement in the radiation hardness of the material. In this contribution we investigate the effects of 2 MeV electron irradiation, up to a fluence of 5×1016 e/cm2, on the electrical and carrier lifetime properties of p-on-n silicon diodes fabricated on different substrate materials, including HR standard and oxygenated FZ, as well as HR magnetic Czochralski silicon, with a higher intrinsic oxygen contents. A progressive degradation of the characteristics is observed for all devices, pointing to a generation of bulk damage. Interestingly, a significant increase of the effective carrier concentration is observed after the highest fluences for all materials. Under the limited experimental conditions studied, no significant changes are observed for diode characteristics subjected to a thermal annealing treatment at 80 °C. This degradation in the electrical properties should be taken into account for the use of such HR Si materials under high-energy electron environments.