A comparison of 48 MeV Li3+ ion, 100 MeV F8+ ion and Co-60 gamma irradiation effect on N-channel MOSFETs

N-channel MOSFETs were irradiated by 48 MeV Li3+ ions, 100 MeV F8+ ions and Co-60 gamma radiation with doses ranging from 100 krad to 100 Mrad. The threshold voltage (VTH), voltage shift due to interface trapped charge (ΔVNit), voltage shift due to oxide trapped charge (ΔVNot), density of interface trapped charge (ΔNit), density of oxide trapped charge (ΔNot), transconductance (gm), mobility (μ) of electrons in the channel and drain saturation current (ID Sat) were studied as a function of dose. Considerable increase in ΔNit and ΔNot, and decrease in VTH, gm and ID Sat were observed in all the irradiated devices. We correlated the degradation of μ with the ΔNit and the effect of ΔNot is found to be negligible for degrading the μ. The maximum degradation was observed for the devices irradiated with Co-60 gamma radiation when compared with those irradiated with ions, since gamma radiation can generate more trapped charge in field oxide when compared to the high energy ions.