60Co gamma radiation total ionizing dose combined with conducted electromagnetic interference studies in BJTs

The influence of combined 60Co gamma radiation total ionization dose (TID) and conducted electromagnetic interference (EMI) in bipolar transistors was studied. The BJTs were set at forward active bias during the entire irradiation processes to investigate the current gain degradation. The experimental results demonstrated that the base current increases under the influence of EMI, TID and combined TID with EMI due to the recombination currents in the emitter-base spacer of the transistor. The ideality factor n investigated showed that TID was approximately equal to 2 and the combination of TID and EMI was greater than 2. Meanwhile, the degradation quantity of the device current gain βTID+EMI tested with combined TID and EMI irradiation was observed to be more severe than that of βTID or βEMI tested only with TID or EMI at low bias VBE region (<0.65 V). However, the degradation trends of the dc characteristics of the tested devices at high VBE region (>0.6 V) became smaller under different experimental conditions (EMI, TID, TID + EMI). Finally, the current gain degradation levels of the tested devices were compared (βTID+EMI > βTID > βEMI).