A comparison of radiation tolerance of field effect and bipolar transistors

An analytical comparison of the radiation tolerance of conventional silicon field effect transistors and of silicon bipolar transistors has been performed. The channel or base thickness has been used as the respective critical variable, since it measures the degree of difficulty of device fabrication. For field effect transistors, the pinch-off voltage has been used as a free parameter. Based on recent lifetime degradation data for bipolar transistors and on carrier removal data for material of variable resistivity, it is shown that field effect transistors are not inherently more radiation tolerant than bipolar transistors. Only field effect transistors with pinch-off voltages well in excess of 10 volts appear superior to bipolar transistors.