8 MeV electron irradiation effects in silicon photo-detectors

Results of investigations on the electrical properties of n+–p–p+ silicon (Si) photo-detectors irradiated with 8 MeV electrons are presented. The photo-detectors were irradiated with electrons of doses up to 100 kGy. Current–voltage (I–V) and capacitance–voltage (C–V) characteristics under dark conditions were measured as a function of dose. A significant change in the diffusion component of the saturation current is observed after irradiation, while the generation-recombination component of the saturation current remains almost unchanged. The series resistance is found to increase with increasing dose while the shunt resistance and carrier concentration decrease with dose. Optoelectronic properties, namely short circuit current Isc, open circuit voltage Voc under air mass zero illumination and spectral response, were measured at various doses. From the spectral responses of the devices, the minority carrier diffusion length was estimated.