Single-Event-Induced Charge Collection in Ge-Channel pMOS FinFETs

Peak transient currents due to pulsed-laser or heavy-ion irradiation of Ge pMOS FinFETs are nearly independent of gate bias. This is because the prompt photocurrent is due primarily to a transient source-drain shunt. In contrast, long-term diffusion charge collection is strongly gate-bias dependent. This bias dependence results from hole injection from the source in response to the transient increase in electron concentration in the channel. The transients measured at the source terminal change polarity when the strike location moves from the source to the drain, but this effect does not occur for the transients measured at the drain terminal. Charge collection mechanisms are studied using TCAD simulations.