The effects of ionizing radiation on commercial power MOSFETs operated at cryogenic temperatures

This is the first report of commercial n- and p-channel power MOSFETs exposed to ionizing radiation while operating in a cryogenic environment. The transistors were exposed to low energy X-rays while placed in a liquid nitrogen-cooled dewar. Results demonstrate significant performance and survivability advantages for space-borne power MOSFETs operated at cryogenic temperatures. The key advantages for low-temperature operation of power MOSFET's in an ionizing radiation environment are: (1) steeper subthreshold current slope before and after irradiation; (2) lower off-state leakage currents before and after irradiation; and (3) larger prerad threshold voltage for n-channel devices. The first two points are also beneficial for devices that are not irradiated, but the advantages are more significant in radiation environments. The third point is only an advantage for commercial devices operated in radiation environments. Results also demonstrate that commercial off-the-shelf power MOSFETs can be used for low-temperature operation in a limited total dose environment (i.e., many space applications).<
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