Si BJT and SiGe HBT performance modeling after neutron radiation exposure

Theeffects of neutron irradiation on both Si bipolar junction transistor (BJT) and SiGeheterojunction 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.