Combined Neutron and Thermal Effects on Bipolar Transistor Gain

An approximate model has been developed to extend room temperature neutron transistor gain characterizations to temperature extremes. The model can extrapolate transistor gain specifications without recharacterizing device types for temperature or neutron effects. The simplified model can be inaccurate at low currents and for those transistors where the surface effects are significant. However, the model shows good agreement with experiment over two orders of magnitude in operating current level and can be used as a valuable design/analysis tool. Comparison of neutron degradation data (at room temperature) with the prediction based on transistor gain bandwidth product (fT) can be used to estimate the significance of surface effects.