Two-Dimensional Modeling of N-Channel MOSFETs including Radiation-Induced Interface and Oxide Charge

A model of the radiation-induced changes produced in n-channel MOSFETs is presented. The model is applicable for the unirradiated device and accurately predicts device characteristics for doses of up to 500 krad(Si). The model is verified by comparing the results obtained with the model to n-channel MOSFETS for doses 0, 10, 50, 100 and 500 krad(Si). Detailed comparison of the model with a 7.8-μm channel length transistor, to eliminate short-channel effects, shows excellent agreement between the model and measured current-voltage characteristics in the subthreshold region, the triode region, and the saturation region. Analysis of the model parameters shows that the oxide charge and interface trap density are linear with dose in these devices. The mobility decrease used in the model can best be accounted for by the combined effects of scattering from oxide and interface charge in the channel.