An investigation of 60Co gamma radiation induced damage in N-channel MOSFETS at cryogenic temperature

Abstract

N-channel depletion metal oxide semiconductor field effect transistors (MOSFETs) were irradiated with 60Co gamma radiation in the dose range of 100 krad to 6 Mrad at cryogenic (77 K) and room temperatures (300 K). The MOS devices irradiated at 77 K and 300 K were characterized at 77 K and 300 K respectively. The different electrical parameters of MOSFET such as threshold voltage (Vth), density of interface trapped charges (ΔNit), density of oxide trapped charges (ΔNot) and mobility of the charge carriers (μ) were studied as a function of total dose. A considerable increase in ΔNit and ΔNot and decrease in Vth was observed after irradiation. The 77 K irradiation results were then compared with 300 K irradiation results and found that the degradation in the electrical characteristics is more for the devices irradiated at 300 K.