On the picosecond switching of a high-density current (60 kA/cm$^2$) via a Si closing switch based on a superfast ionization front

A silicon closing switch with successive breakdown mode of diode structures based on a superfast ionization front is studied. In a coaxial line with a 48-$\Omega$ wave impedance, pulses with an amplitude above 100 kV and a rise time of 40 ps at an amplitude level of 0.3–0.9 are obtained. The maximum output-voltage rise rate is 2 MV/ns at a switching-current peak density of 60 kA/cm$^2$. Numerical simulation shows that the switching time of individual structures of the device is 7–15 ps at a reverse-voltage rise rate of $>$100 kV/ns per structure under experimental conditions. The electric field in the $p$–$n$ junction reaches the Zener breakdown threshold ($\sim$ 10$^6$ V/cm) even in the case where the diode structure contains process-induced deep-level centers with concentrations of up to 10$^{13}$ cm$^{-3}$.