Investigating the Electric Field Influence on Total Ionization Dose Effects in Space Radiation for Carbon Nanotube Field Effect Transistors

Carbon nanotube field effect transistors (CNTFETs) are considered ideal components for radiation-hardened integrated circuits (ICs) due to their material and structural properties. CNTFETs have been shown to have good tolerance to total ionizing dose (TID) effects under no-bias condition. However, in practical applications, ICs typically operate under specific bias conditions. It is necessary to evaluate the TID effects of CNTFETs under different bias conditions. A wafer-level chip probe power-up system was designed to power CNTFETs during Co-60 γ-ray irradiation. The experimental results show that the bias condition greatly affects the TID tolerance of the CNTFET. Under the no-bias condition, the CNTFET is tolerant to TID up to 2000 k rad (Si). On the contrary, under off-bias condition, the failure occurs at 200 k rad (Si). The failure of the CNTFET is characterized by out-of-control gate voltage and its failure mechanism is analyzed. It is attributed to the breakdown of the gate dielectric (HfO2) between the gate and the source via the time-dependent dielectric breakdown (TDDB) effect.