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

N-channel depletion metal oxide semiconductor field effect transistors (MOSFETs) were irradiated with Co-60 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 (V-th), density of interface trapped charges (Delta N-it), density of oxide trapped charges (Delta N-ot) and mobility of the charge carriers (mu) were studied as a function of total dose. A considerable increase in Delta N-it and Delta N-ot and decrease in V-th 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.