Experimental Research Of Semiconductor Opening Switch (SOS) Effect

Semiconductor Opening Switch is a pulsed power opening switch and has characteristics of great current, high voltage and di/dt, long lifetime and high repetitive rate. Inductive storages and opening switch applied in pulse power technology are developing rapidly and because the magnetic field energy stored in inductive storages is approximately two orders of magnitude higher than the electric field energy in capacitive storages, pulsed power generators based on SOS have very extensive application field and market prospect.SOS is a sort of diodes of p+-p-n-n+ structure. This paper is mainly to research the opening process of this new device and test the SOS effect. A model allowing electron-hole plasma dynamics at super-high injection levels to be analyzed was introduced to account for the SOS effect and study the processed in semiconductor structures. The model takes into consideration the actual doping profile of semiconductor structure and the following elementary processes in the electron-hole plasma: the diffusion and drift of current carriers in strong electric fields; recombination at deep impurities; Auger recombination; impact ionization in a dense plasma. The emulational results based on this model have show that the current interruption process occurs not in the low-doped n base of the structure at first, but in its high-doped p region. Therefore, SOS effect represents a qualitatively new principle of current switching in semiconductor devices.The SOS effect testing circuit is designed by analyzing SOS double pumping circuit, and the sampleⅠ(diodes made by our lab) and the sampleⅡ(fast recovery diode) is tested on this circuit. The experiment results have shown that the sampleⅠis nearly to have the SOS effect, the maximun of its coefficient of the reverse overvoltage Kov can reach 1.9 and the minimun of FWHM(Full Wave at Half Maximum) of the reverse overvoltage tP can reach 120ns. The characteristics of the diodes are deeply affected by changing element parameters,pumping voltage and load impedance in testing process.According to the structure of SOS diodes and the technics condition of our laboratory, the devices facture flow is designed and the chemical eroding method is introduced to replace the traditional rubbing way. The corrosion solution ratios adapting to the technics in laboratory are acquired by numerous experiments, which have been applied to the preparation process of chips.