Leakage currents due to radiation induced electron–hole pairs in NMOS devices

Total ionizing dose effects on NMOS devices have been studied as a function of the irradiation dose. The gate oxide thickness of NMOS devices for experiments was 85 Å, the gate width was 10 μm and the gate length was 5 μm. These devices were irradiated using 1-MeV protons and 1-MeV electrons with total irradiation doses of 1, 5, 10, 50, 100 and 500 kGy, respectively. The changes in the electrical characteristics were measured using HP4155A semiconductor parameter analyzer. The changes after 1-MeV electrons irradiation were large compared to those after 1-MeV protons irradiation. The radiation induced electron–hole pair generation in MOS devices was also numerically simulated using a GEANT4 code.