Comparative effect of gamma total dose on surface mount and non surface mount bipolar transistors

High gain silicon NPN transistors in an SOT23 package are found to show up to 50% loss in gain at doses as low as 30Gy(Si). Devices of similar construction in conventional packages, showed significantly less degradation. The devices tested were all NPN epitaxial type transistors with h/sub EE/ (small signal current gain) in the range 250-2000. Measurements were made for total doses in the range 25-100Gy(Si). No annealing was observed over a period of a few days.<
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