Ionizing Radiation Effects on Power MOSFETS during High Speed Switching

Data on the effects of gamma radiation on the electrical characteristics of power VDMOS transistors are presented. The devices were exposed to radiation while the gate voltage was switching at 100 kHz or while held at a dc voltage. Several drain voltage configurations were also explored. The threshold voltage shifts observed begin to saturate at relatively low doses (~0.1 Mrad(Si)) for all but the worst case bias (VG = +10 V). The threshold voltage shifts do not show significant dependence on drain voltage. The devices studied appear to be approximately an order of magnitude more efficient in trapping radiation generated holes than would be expected in a state-of-the-art radiation hardened planar MOSFET.