Simulation of the subnanosecond cutoff of current in high-power semiconductor diodes

The subnanosecond cutoff of high-density current in the structure of a semiconductor opening-switch diode is investigated within a physico-mathematical model. The model takes into account the space charge and the effect of the electric field, temperature, electron-hole scattering, and scattering by ionized impurities on the carrier mobility. It is established that subnanosecond cutoff of current with a density of several kA/cm2 occurs at a p-n junction depth exceeding 180 μm, forward pumping time less than 60 ns, and reverse pumping time less than 20 ns. This process is due to the formation of three high-field regions in the stage of current cutoff. Two regions, expanding with a nearly constant velocity, are located in the p region, and the third one, slowly expanding, is in the n region. It is shown that, to implement subnanosecond current cut-off, a set of conditions for the circuit parameters (determining the pump current duration and density) and the dopant profile in the semiconductor structure should be satisfied simultaneously. The simulation results are compared with the experimental data.