D.c. and low frequency noise characteristics of γ-irradiated gate-all-around silicon-on-insulator MOS transistors

Abstract

This paper discusses the impact of γ-irradiation on the static current-voltage and low-frequency noise parameters of so-called gate-all-around (GAA) Silicon-on-Insulator n-MOSFETs. The devices are irradiated up to a total dose of 30 Mrad(Si). The threshold voltage of the devices under test shows a rebound behaviour as a function of dose, i.e. after an initial reduction of V T, an increase sets in resulting in a final value which is higher than the initial threshold voltage. A similar tendency is found for the normalised noise spectral density, i.e. a turnaround is observed, indicating a close relationship between the above two parameters. The maximum transconductance on the other hand decreases monotonously with dose. Because of the specific nature of the GAA device, an alternative procedure is proposed to extract the contribution of oxide-trapped charge and interface charge to the total threshold voltage shift, which yields a qualitative agreement with the measurements.