Radiation causes oxide charge buildup which can degrade carrier mobility in the inversion layer of a metal-oxide-semiconductor field-effect transistor (MOSFET). An expression for the carrier mobility in MOSFETs due to oxide charge scattering has been derived. The model predicts the mobility degradation given any specified charge density profile in the oxide. It accounts for screening of oxide charges by channel carriers. To validate the proposed model we performed an experiment to place a measured quantity of charge at a definite position in the gate oxide and then measured the mobility degradation. The experimental results are in good agreement with the predictions of the model.

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Abstrad-The effects of ionizing radiation and hot electrons on the BiCMOS switching response have been studied. The radiation induced surface recombination current in the base of the bipolar transistor and the radiation and hot electron induced resistive leakage paths in the BiCMOS structure have been modeled as a function of the interface state density and the oxide trapped charge density. An equivalent circuit model of a BiCMOS inverter, including radiation and hot electron effects on the MOSFET and the bipolar transistor and leakage paths in the BiCMOS structure is proposed. The proposed model is compared with experimental data and with MEDICI simulations and the agreement is good.

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