Effect of 1 MeV neutron-irradiation on the electrical properties of Si-based diodes

Abstract This study investigates the impact of 1 MeV neutron irradiation on the electrical properties of n-type silicon (n-Si) Schottky diodes, focusing on high fluences of 10 15 and 10 16 n/cm 2 . Current-voltage (I-V) measurements were conducted on diodes before and after irradiation to assess changes in conduction behaviour. Results reveal a significant shift from exponential diode characteristics to ohmic conduction with increasing fluence, a phenomenon less explored compared to lower-fluence studies (e.g., <10 14 n/cm 2 ) documented by the RD50 collaboration and CERN experiments. The reverse current increased by factors of 3.5 and 82 at 10 15 and 10 16 n/cm 2 , respectively, attributed to radiation-induced defects generating minority carriers. In the forward bias, minimal change was observed at 10 15 n/cm 2 (factor of 1.14 decrease), while a marked increase (factor of 3.64) occurred at 10 16 n/cm 2 , linked to enhanced majority carrier generation by defects. This transition to ohmic behaviour, corroborated by a reduction in rectification ratio from 45 (unirradiated) to 2 (10 16 n/cm 2 ), reflects defect levels pinning the Fermi energy near the intrinsic position. These findings elucidate the effects of high-fluence neutron irradiation on silicon diodes, offering valuable insights for developing radiation-hard detectors for extreme environments, such as the High-Luminosity LHC.