Investigation of irradiation effects and model parameter extraction for VDMOS field effect transistor exposed to gamma rays

In this article, the effects of gamma ray irradiation on VDMOSFET and the corresponding parameter extraction are investigated. The transfer and output characteristics are evaluated to quantify the radiation tolerance. Threshold voltage decreases as the accumulated dose increases, while increases after 168-h high-temperature annealing. To explore the degradation mechanism, BSIM compact model is adopted and corresponding model parameters are extracted. The created oxide-trapped charges are found to dominate the threshold voltage shift after irradiation, and the irradiation-induced interface states are responsible for the performance degradation after subsequent high-temperature annealing. The underlying physical mechanisms are analyzed and discussed in detail.