The Effects of Neutron Radiation on Second Breakdown and Thermal Behavior of Silicon Transistors

A method of measuring and the subsequent analysis of this data has indicated that the "thermal time constant" of silicon diffused transistors decreases with increasing neutron dosage. Emperically, it was noted that thermal time constant degradation constants, Kÿ, can be assigned to all devices examined. For the silicon planar devices studied, degradation constants varied from 2.6 × 10-13cm2/neut for the radiation resistant devices, to 1.4 × 10-12 cm2/neut for other devices examined. By examining previous data for single diffused transistors the thermal time constant degradation factor was 2 × 10-11 cm2/neut. The conclusion of this report is that the "thermal time constant, which is related to second breakdown, effectively degrades upon exposure to neutron radiation, thereby decreasing the safe operating area of the device. However, the extent of degradation per dose may be predictable by data presented in the text.