Total Ionizing Dose Effects of SiGe HBTs Induced by ⁶⁰Co Gamma-Ray Irradiation

For evaluating the SiGe heterojunction bipolar transistors (HBTs) performance during and after gamma-ray irradiation, the characteristics of the direct current (dc) gain of the test samples changed with increasing irradiation dose, and collector current injection levels during ⁶⁰Co gamma irradiation were measured and analyzed. The experimental results of the typical dc and alternating current (ac) electronic parameters before and after irradiation revealed that the base current I_b, the collector current I_C, the dc current gain, and the maximum oscillation frequency f_max exhibited degradation. While other electronic parameters including the cut-off frequency f_T, the ac current gain |H₂₁|, and output capacitance C_BC did not exhibit any significant change compared with those of pre-irradiation. The degradation mechanisms of the typical dc and ac parameters measured in this work were primarily analyzed. The tested results of SiGe HBTs offered some reference data for evaluating the behavior of the test type of device operated in an ionizing radiation environment.