  The total ionizing radiation (TID) response of commercial NPN silicon
germanium hetero-junction bipolar transistors (SiGe HBTs) produced domestic
were investigated under the dose rate of 800mGy(Si)/s and 1.3mGy(Si)/s with
Co-60 gamma irradiation source, respectively. The changes of the transistor
parameter such as Gummel characteristics, excess base current before and after
irradiation are investigated. The results of the experiments shows that for the
KT1151, the radiation damage have slightly difference under the different dose
rate after the prolonged annealing, shows an time dependent effect(TDE). But
for the KT9041, the degradations of low dose rate irradiation are more higher
than the high dose rate, demonstrate that there have potential enhanced low
dose rate sensitive(ELDRS) effect exist on KT9041. The underlying physical
mechanisms of the different dose rates response induced by the gamma ray are
discussed.
