Radiation damage studies on silicon diodes irradiated with electrons

Radiation damage of silicon diodes induced by electrons with energies in the range between 1.5 MeV and 15 MeV has been studied. Low energy electrons lead to displacement the displacement of silicon atoms caused by low energetic recoil atoms, resulting in the creation of isolated point defects. At higher energies the probability for the formation of cluster defects becomes dominant. The study aims at understanding the energy dependence of the cluster defect formation and the structure of the electrically active defects. N-type silicon diodes with different carbon and oxygen concentrations were chosen for irradiation. Electrical characterization of the irradiated sensors by current- voltage (I-V), capacitance-voltage (C-V) characteristics and spectroscopy of electrically active defects by Deep Level Transient Spectroscopy (DLTS) and Thermally Stimulated Current (TSC) methods were performed. From the I-V measurements the current -related damage parameter α was extracted and compared to the classical NIEL (Non-Ionizing-Energy-Loss) and *effective* NIEL was made. It is found that for electrons with energies in the range 1.5 to 15 MeV the scaling of α with the classical NIEL is not valid. From DLTS and TSC measurements the ratio of point to cluster defects as function of electron energy and the introduction of different defects is determined.