The thin emitter structure was introduced into reversely switched dynistor(RSD) to improve its turn-on characteristics. According to the analysis of turn-on condition, thin emitter structure is capable of reducing the extraction action for the triggering plasma layer P1 during turn-on process, and satisfying the requirement that triggering electric charge cannot be exhausted and therefore enables RSD to turn on uniformly. The on-state thin emitter RSD was equivalent to an asymmetric pin diode model. The simulation result shows that the forward voltage drop of RSD falls with the decrease of doping dose in p+-emitter in a certain range, and when the doping concentration is extremely low, the decrease of the width of p+-emitter can obtain a low forward voltage drop. Thin emitter RSD chips were made by sintering Al on n-Si. The test result shows that their turn-on process is uniform and the voltage drop is 7.5 V when the peak conversion current is 5 500 A.
The power dissipation characteristics of pulsed power switch reversely switched dynistors (RSDs) are investigated in this paper. According to the expressions of voltage on RSD,derived from the plasma bipolar drift model and the RLC circuit equations of RSD main loop,the simulation waveforms of current and voltage on RSD are acquired through iterative calculation by using the fourth order Runge-Kutta method,then the curve of transient power on RSD versus time is obtained. The result shows that the total dissipation on RSD is trivial compared with the pulse discharge energy and the commutation dissipation can be nearly ignored compared with the quasi-static dissipation. These characteristics can make the repetitive frequency of RSD increase largely. The experimental results prove the validity of simulation calculations. The influence factors on power dissipation are discussed. The power dissipation increases with the increase of the peak current and the n-base width and with the decrease of n-base doping concentration. In order to keep a low power dissipation,it is suggested that the n-base width should be smaller than 320μm when doping concentration is 1.0×10 14 cm 3 while the doping concentration should be higher than 5.8×10 13 cm 3 when n-base width is 270μm.
