Numerical investigation of the nanosecond opening-mechanism of drift step recovery diodes

A circuit-fluid coupled model is proposed for describing the dynamics of the electron-hole plasma and the evolution of the electric field in the drift step recovery diodes (DSRDs). The model takes account of the real doping profile of the p+-p-n+ type silicon DSRD and the elementary processes such as the impact ionization, Shockley-Read-Hall recombination and Auger recombination. The current opening process of the DSRD is simulated with the proposed model and then the nanosecond opening-mechanism is investigated. The opening process is found to appear at the base region of the DSRD, due to the high density electron-hole plasma formed at the forward pumping period. According to the opening rate, the opening process can be divided into two stages: a slow stage near the p+-p boundary and an abrupt one at p-n junction. Moreover, simulation results show that the p+-p-n+ type DSRD with a lower base tends to generate pulses with shorter rise time and higher peak voltage.