Charge Trapping Effects on n-MOSFET Current Mirrors Under TID Radiation.

Abstract

This study aims to evaluate the effects of total ionizing dose (TID) radiation on the performance of n-MOSFET current mirrors. We propose an ovel experimental approach to analyze the interaction between charge trapping in the MOSFET gate oxide and the resulting current mirror degradation by subjecting devices to TID doses from 50 krad(Si) to 300 krad(Si) using a 60Co gamma source Experimental data show that threshold voltage shifts by up to 1.31 V and transconductance increases by 27%. This degradation leads to this a reduction of more than 10% in current mirror output accuracy occurs at the highest dose. These quantitative criteria establish a clear benchmark for assessing the impact of TID on current mirror performance. These effects are attributed to positive charge trapping in the gate oxide and at the Si-SiO₂ interface induced by ionizing radiation. This study focuses exclusively on radiation effects; electrical stress phenomena such as over-voltage or electrostatic discharge (ESD) are not addressed. The results highlight the critical importance of accounting for TID effects when designing high-performance n-MOSFET current mirrors for radiation-hardened applications.