60Co gamma and high energy ion impacts on threshold characteristics and its recovery in N-channel depletion MOSFETs

N-channel depletion MOSFETs are irradiated with 140 MeV silicon ions (Si10+) and Co-60 gamma radiation separately from 100 krad to 100 Mrad of total dose. The current-voltage (I-V) variations in MOSFETs are characterized systematically before and after 140 MeV silicon ion and Co-60 gamma irradiation. Threshold voltage (V-TH), leakage current (I-L), density of oxide trapped charges (Delta N-it) and density of interface trapped charges (Delta N-ot) are measured. The impact of Co-60 gamma radiation on V-TH, I-L, Delta N-it and Delta N-ot of MOSFETs is found to be more when compared to 140 MeV silicon ions. Isothermal annealing studies are performed on the irradiated devices, and the recovery in V-TH is observed to be more in the case of 140 MeV silicon ions-irradiated MOSFETs when compared to Co-60 gamma-irradiated MOSFETs.