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 devicemaintains 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.