Analyze of current components in NMOS single event transient

3D mixed-mode simulation is used to research current components of SET current pulse in inverter chain, compared with that in a single NMOS. It is found that parasitic bipolar conduction current is the major component in SET current of single NMOS, but not in deep-submicron CMOS circuit. The paper provides a detailed discussion of source current in SET and it shows that negative and positive components of source current are related to bipolar amplification and diffusion of carriers respectively.