Research On 4H-SiC Photoconductive Switch With Low On-state Resistance

Photoconductive semiconductor switch(PCSS) is a switch controlled by light. The device has many applications in generating high power pulses due to their compact geometry, large capacity of power, high breakdown voltage, small conduction resistance, fast response, high repetition frequency,reliability and extremely low switching jitter. Because of the fact that it can produce picosecond pulses of electricity, researchers pay attention to PCSS in the field of terahertz. As Si C single crystal material growth technology becoming more and more mature and its superior performance, the research of Si C PCSS was promoted.In this paper, lateral geometry, contact face illuminated 4H-Si C PCSS is presented.The research background, the working principle and the development history of PCSS are introduced. According to carrier continuity equation, the output performance of Si C PCSS is simulated. Based on the principle of test circuit, the component parameters are simulated and detemined. A experimental system was set up to test the performance of the switch.The factors which affect the conduction properties are mainly researched. Phosphate ion implantation is used to fabricate the device, and the results show that it can significantly reduce the switch conduction resistance and improve the conduction performance. The influence of the laser spot size and the light intensity distribution to the on-state characteristics are researched. The light path of the experimental system is improved. The result shows that due to the increased efficiency of the light absorption and the decrease of the local current density, such switches achieve a smaller minimum on-state resistance and a low damage probability when there is a laser spot after optimization.Our switches with the good performance of breakdown voltage above 10 k V and 3.17 ?/mm minimum on-resistance are fabricated.