A new approach to model the radiation-induced threshold voltage shift in fully-depleted SOI MOSFET has been implemented for circuit simulations.The model is validated by comparison of simulated and measured post-radiation device characteristics of MOSFETs in the literature.The model has such advantages as simple analytic expression

clear physical meaning

and easy extraction of used parameters.The model can be used as a basic circuit simulation tool for analysing hardened SOI MOS transistors exposed to a nuclear environment in the low-dose range.Additionally

the discussion presented here supports that the large top threshold voltage shift of the fully-depleted MOSFET is attributed to the large radiation induced oxide charge in the buried oxide which was coupled to the top gate.Thinner buried oxides

which are less dose sensitive than thicker ones

can not necessarily improve the radiation hardness of fully-depleted transistors because of the higher coupling effect.