Electro-Thermal Simulation of Current Filamentation in 3.3-kV Silicon p + - n - - n + Diodes with Differenth Edge Terminations

We investigate the current filamentation behavior during reverse recovery in high-voltage 3.3-kV silicon p + - n - - n + diodes with transient S—shape negative differential resistance characteristics. The transient I — U—bistability occuring in the reverse recovery period leads to a non-uniform current distribution in the diodes when they are turned off with a high current rate di/dt. In this paper we compare the filamentation behavior of diodes without any edge termination with that of diodes providing a non-optimized JTE (Junction Termination Extension), an optimized JTE, and a beveled edge termination by means of isothermal and electro-thermal device simulations. The observed differences are explained by analyzing the transient electric-field, current-density and temperature distributions in the devices.