On the formation of stationary destructive cathode-side filaments in p+-n--n+ diodes

Analyzing the dynamics of current filaments is essential for a correct understanding of SOA limitations. Current filaments can occur during the reverse-recovery period of p(+)-n(-)-n(+) diodes. In this work, we apply the results from an analysis of the plasma-front dynamics for the one-dimensional case to conditions under which current filaments appear in the depletion layers due to dynamic avalanche. We show that the anode-side plasma front velocity is higher in the vicinity of the filament than far away from the filament center, favoring the evolution of a lateral traveling anode-side filament. Furthermore, we find that the cathode-side plasma front changes its vertical propagation direction when a dynamic avalanche in the cathode-side depletion layer causes current crowding. As a result, the cathode-side depletion layer in the vicinity of the filament decreases, favoring the formation of a standing cathode-side filament that may cause final destruction of the device. The analytical results are in good agreement with numerical simulations and results of previously published work.