New superfast power closing switched-dynistors on delayed ionization

Abstract

The fastest from known semiconductor electrically triggered power closing switches have turn on times of dozens of nanoseconds at /spl sim/1 kV blocking voltage and /spl sim/100 A switching current. Any attempt to increase the device voltage leads to an increase of the device thickness and an increase of turn-on times. Spark gaps, although faster, have severely limited lifetimes. The effect of delayed ionization has allowed for the development of a new kind of power superfast switch-silicon avalanche shapers (SAS)-in which time of flight limitation on speed has bean overcome. This approach has been used to develop new power superfast devices-fast ionization dynistors (FID)-which behave like a thyristor in that they have two steady states: nonconducting; and high-conducting. The fast (less than 1 ns) transition from the nonconducting to high-conducting state is induced by delayed ionization by the application of a short (nanosecond) high-voltage (kilovolts) pulse to the blocking p-n junction of the multilayered n/sup +/pnp/sup +/ semiconductor structure. Due to regenerative feedback, as in usual thyristors, the structure remains in the high-conducting state infinitely. To switch on the device, it is necessary to break the current by using an external circuit.