Complexity of the total dose radiation response of fully depleted silicon-on-insulator NMOSFETs

With bias conditions changed during irradiation, the bias dependence of the total dose radiation response of fully depleted (FD) silicon-on-insulator (SOI) n-channel MOS transistors (NMOSFETs) is investigated preliminarily. It is found that the threshold voltage shift of the FD SOI NMOSFETs as a function of total dose exhibits an abrupt inverse change, namely, a unexpected rapid reduction, with increasing total dose, when the bias condition is changed from OFF-state into transmission gate (TG). It is also found that it is not always effective to reduce the total dose sensitivity of the tested transistors by applying a negative voltage to their back gates during irradiation. In addition, the rebound of the threshold voltage shift has been observed clearly with dose for the transistors biased using both the OFF-state and the TG during irradiation, which can be partly attributed to the radiation induced electron traps located at the interface between the silicon film and buried oxide (BOX).