Second breakdown in simple junction bipolar devices

Approximate solutions are given for a number of problems which arise in the analysis of second breakdown in junction bipolar devices. The purpose of these solutions is to provide a qualitative picture of device behavior and a method of checking more rigorous numerical analyses. Avalanche breakdown and sustaining voltages are shown for cylindrical and spherical geometries. Variation of bulk resistivity with temperature is demonstrated to be sufficient to cause a sharp drop in voltage, even without a current constriction. An inverse relationship between input power and time to failure is shown for high currents. An analysis of melt channel development is provided for both conventional and SOS structures. An improved equivalent circuit is suggested for current mode second breakdown.