Radiation Hardness of Minimum Ionizing Particle Detectors Based on SiC p+n Junctions

n this work we analyzed the radiation hardness of SiC p+/n diodes used as minimum ionizing particle (MIP) detectors after very high 1 MeV neutron fluences. The diode structure is based on ion implanted p+ emitter in an n-type epilayer with thickness equal to 55 ?m and donor doping ND = 2×1014 cm-3. The diode breakdown voltages were above 1000 V. At 1000 V the leakage currents are of the order of 1 nA for all the measured diodes. The full depletion voltage is near 220-250 V. The charge collection efficiency to minimum ionising particle has been investigated by a 90Sr ? source. At 250 V the collected charge of the unirradiated diodes saturates near 3000 e-. At bias voltages over than 100 V the energy spectrum of the collected charge was found to consist of two peaks clearly separated. At around 250 V the signal saturates, in agreement with CV results. These devices have been irradiated considering 6 different fluences, logarithmically distributed in the range 1014-1016 1 MeV neutrons/cm2. The leakage current after irradiation decreases. The collected charges decrease for increasing fluences, remaining very high only until some 1014 n/cm2.