High-power Gaas Photoconductive Switch Design Techniques

High voltage, high current, low inductance, fast resistive transition, and precise control are the critical component parameters of a semiconductor switch that can enable the fielding of a compact pulse power system. Extrinsic, semi-insulating GaAs photo-conductive switches have the potential to fulfill these critical requirements. The availability of this type of switch also enables innovative approaches to pulse power system design and implementation.In this paper both the domestic and foreign present research progress of PCSS, its importance in defence construction and the main problems in development are introduced. Under the background of HPW (high power weapon), PCSS with high hold-off voltage are designed whose hold-off electrical field is up to 5kV/mm, and peak output power is 5MW. The working mechanism of PCSS is studied, and the analysis of relationship between carrier concentration and electrical field are given. Construction models of co-plan and opposed PCSS are built. With the help of ANSYS and construction model, the influence of different structures and different electrode insulated layers on the electrical field distribution is analyzed. Mathematical model of inner carriers is built by the basic idea of Collective Impact Ionized theory. The hold-off voltage of opposed structure PCSS are predicted by the mathematical model and Silvaco sofeware suite.Co-planner PCSS with different insulating layers is tested and the results are coincident with the simulation. With the help of Silvaco, the hold-off ability of PCSS in simulation is verified and the experiment shows that opposed PCSS has higher hold-off voltage. Using the simulation result, analysis is given to explain the reason for better hold-off ability. The phenomenon such as reduce of hold-off voltage in the high frequency laser trigger experiment and the change of lock-on threshold voltage are also explained by the Silvaco simulation results.