Reliability studies on NPN RF power transistors under swift heavy ion irradiation

NPN RF power transistors were irradiated with 140 MeV Si10+ ions, 100 MeV F8+ ions, 50 MeV Li3+ ions and Co-60 gamma radiation in the dose range from 100 krad to 100 Mrad. The transistor characteristics are studied before and after irradiation from which the parameters such as Gummel characteristics, excess base current (ΔIB = IBpost − IBpre), dc current gain (hFE), transconductance (gm) and collector-saturation current (ICSat) are determined. The degradation observed in the electrical characteristics is almost the same for different types of ion irradiated NPN RF power transistors with similar total doses although there is a large difference in the linear energy transfer (LET) of the ions. Further, it was observed more degradation in DC I–V characteristics of ion irradiated devices than the Co-60 gamma irradiated devices for higher doses.