Numerical simulation on factors affecting critical frequency of high-power photoconductive semiconductor switch

The heat dissipation process of GaAs photoconductive semiconductor switch (PCSS) in nonlinear mode has been simulated based on finite difference time domain method (FDTD). Factors affecting the critical frequency, such as location, radius, number of current filament, dimensions of PCSS chip and environment temperature were discussed. The results are as follows: the critical frequency exponentially increases as radius and the number of current filament increases, it decreases exponentially as distance between location of current filament and surface of chip increases and thickness of chip increases. The critical frequency decreases linearly as environment temperature rises in a special range.