An analysis of 100MeV F8+ ion and 50MeV Li3+ ion irradiation effects on silicon NPN rf power transistors

Abstract: The dc characteristics exhibited by NPN power transistors are studied systematically before and after irradiation by 100MeV F8+ ions and 50MeV Li3+ ions in the dose range of 100krad to 100Mrad. The transistor parameters such as excess base current (ΔI B=I Bpost–I Bpre), dc current gain (h FE), transconductance (g m), and collector-saturation current (I Csat) were studied before and after irradiation. The damage factors (k) for h FE were calculated for ion irradiated transistors using Messenger–Spratt relation. The base current (I B) was found to increase significantly after ion irradiation and this in turn decreases the h FE of the transistors. The g m decreases significantly after ion irradiation. Moreover, the output characteristics of irradiated devices also show that the collector current (I C) in the saturation region (I Csat) decrease with increase in ion dose. The observed change in these characteristics may be due to the ion induced generation–recombination (G–R) centers in emitter-base (E-B) spacer oxide and the ion induced point defects and their complexes in the transistor structure. [ABSTRACT FROM AUTHOR]