Fast power switches from picosecond to nanosecond time scale and their application to pulsed power

Abstract

New methods of pulsed power are developed on the basis of new effects in high voltage semiconduc-super fast voltage restoration [ 11; super fast reversible delayed breakdown [2]. This effects have been used to design two types of semiconductor devices: 1) Opening switches -Drift Step Recovery Devices (DSRD) with turn off times O S 2 . 0 ns at operat-2) Closing switches -Silicon Avalanche Shapers (SAS) with turn on times 509200 ps at operating DSRD may be considered as a solid state replacement for plasma opening switches and SAS may be Both types of devices may be assembled in a stack (piled) with dozens of p-n junctions to increase tor p-n junctions, discovered at Ioffe Phisico-Technical Institute, Russia. These effects are: ing voltages 0.5 -2.0 KV for one p-n junction. voltage 3-10 KV for one p-n junction. considered as a replacement for overvoltaged spark gaps. operating voltages. Estimations show that operating voltage for the stack can reach 1 MV in the case of DSRD with turn off time -1 ns and hundreds KV in the case of SAS with tum on times -0.1 ns. It is possible to switch all area of devices uniformly up to the limitations imposed by skin effect. Estimations show maximum switching current up to 10 KA for DSRD and > 2 KA for SAS.2

Tunneling-assisted impact ionization fronts in semiconductors

“…6,7,9,11,12 In both cases we deal with a collective phenomenon of superfast propagation. It is based on avalanche multiplication of the already existing carriers due to impact ionization in a finite narrow region of the device, followed by screening of the electrical field due to Maxwell relaxation in the adjacent spatial region.…”

“…6,9,10 In structures with kilovolt pϪn junctions and large cross-sections, this process is used for sharpening electrical pulses. 9,[11][12][13] This technique allows one to reach voltage ramps with slopes of up to 10 kV/ns, the state of the art in modern pulse power electronics. We demonstrate, that when such a sharp ramp Aϳ10 kV/ns is applied to a fully depleted reversely biased Si p ϩ -n -n ϩ structure, the threshold of tunneling ionization ϳ10 6 V/cm is reached after less than 1 ns, which turns out to be faster than the initiation of avalanche impact ionization.…”

Superfast fronts of impact ionization in initially unbiased layered semiconductor structures

“…23,24 For such structures, often coined as silicon avalanche sharpening diodes, the output power per pulse is by 4 orders of magnitude higher than for TRAPATT diodes ͑10 electronics. [23][24][25][26][27][28] A TRAPATT diode is embedded in a microwave cavity and operated in a regime of periodic oscillations where the impact ionization fronts almost immediately follow each other, so that the nonequilibrium carriers from the previous front passage play an essential role in the excitation of the next front. In contrast, for power kilovolt structures the time interval between two subsequent front passages is large compared to the system relaxation time and each excitation of a front represents an independent event.…”

Improvement of Electromagnetic Pulse Radiation Efficiency

“…If lifetime of the carriers is very short, space charge region (SCR) width (W SCR ) is determined by diffusion length (L p ) and switching off time (τ off ) can be made very small [7][8][9][10]:…”

“…Russian scientists from Ioffe Physic-Technical Institute, St. Petersburg found out another decision in middle of 1980s [7,8]. They proposed to use diodes with larger lifetime of the carriers (drift diodes) and reduce the SCR width by replacement of lifetime of the carriers (τ p ) to current injection time (τ + ) [6]:…”