Gamma Radiation Effects on n-MOSFET I–V Performance

In this work, we investigate n-channel Si MOSFETs commonly used in radia-tion-hardened electronics for space and nuclear applications. Radiation-induced defects degrade the transistor electrical characteristics, particularly the current–voltage behavior. Experimental results reveal a negative shift in the threshold voltage with increasing gamma-ray doses up to 348 krad, mainly attributed to the trapping of positive charges in the gate oxide. In the proposed model, these trapped charges are represented through an effective acceptor concentration NAeff, introduced as a phenomenological parameter to describe their electrostatic influence on the inversion layer, without implying any physical modification of the silicon doping. Static (DC) and small-signal (AC) current models are developed to describe the post-irradiation electrical behavior. Empirical relationships linking device parameters to the total ionizing dose are extracted from experimental I–V measurements. The proposed approach provides a compact framework suitable for low-frequency circuit-level simulations under radiation environments.