Study On Turn-on Characteristics Of High-speed And Power Semiconductor Switch RSD

RSD(Reversely Switched Dynistor) is a high speed and ultrahigh power semiconductor switch, which has characteristics of high breakout voltage,great current,high dI/dt,long lifetime and high repetitive rate etc, and it is a perfect alternative switch of pulsed power systems. RSD consists of several thousands of alternating thyristor and transistor sections and is triggered by an electron-hole layer instead of a local gate electrode. Due to the special device structure, it's triggering process proceeds uniformly and simultaneously over the whole device area, which increases the device's current capability.This thesis researches the principle of RSD and derives the critical condition when the device turns on. RSD would not operate in a quasi-diode mode, until it's reversible stored charge is larger than a critical value which is decided by the internal structure and circuit parameters. In order to build an efficient plasma reservoir, the critical value should be decreased and the injection current to P1-layer should be larger than the extraction one. After a lot of experiments, several conclusions can be received: choosing a thinner and high doping concentration p-base layer,increasing the triggering voltage and decreasing the injection current from p-emitter will do good to the turn-on process of RSD.Turn-on voltage is an important characteristic of the device, which is proportional to the dissipation of RSD. In this thesis, a formula of the largest turn-on voltage is concluded. With the width and resistivity of n-base layer and turn-on current density decreased, the voltage will drop sharply. In this thesis, we have examined the reason that the device fails. The result shows that the inconsistent match between the triggering time and the saturated time of magnetic switch will induce failure, the current will be limited in a small area and the turn-on voltage will rise. Based on the perfect switching characteristics, RSD will be widely used in pulsed power field, should be found in markets as soon as possible. In order to solve the difficulties in fabricating, many experiments are carried out in our lab, different processes building p+ layer in anode and different masks of anode are tested, and these experimental results will help to improve the fabrication process in future. With the development of pulsed power technology and improving of the fabrication and triggering circuit of the device, RSD will be found frequently in our life.