Si BJT and SiGe HBT Performance Modeling after Neutron Radiation Exposure
The effects of neutron irradiation on both Si bipolar junction transistor (BJT) and SiGe heterojunction transistor (HBT) are investigated using Synopsys/ISE TCAD tool. For this purpose the carrier lifetime degradation under irradiation models are included in the program. It was established that at fluence 4×1013 cm-2 the Si BJT exhibited a degradation in current gain of 50% for high level and 80% for low level of E-B junction injection. For SiGe HBT at fluences as high as 1015 cm-2 the degradation of peak current gain is less than 40%, and the device maintains a peak current gain of 80 – 100 after 1015 cm-2. The cut-off and maximum oscillations frequencies are small sensitive to neutron irradiation. The simulation results are in good agreement with experimental data.