Mechanism of Photoelectric Thresholds for Nonlinear GaAs PCSS

The thresholds of bias electric field and trigger laser pulse energy of nonlinear semi-insulating (SI) GaAs photoconductive semiconductor switch (PCSS) have been measured. The characteristics of the photoelectric thresholds are analyzed in theoretically based on Gunn effect electronic theory. The analysis results show that photo-activated avalanche charge domain (PACD) with the peak electric field of about several megavolts per centimeter will be formed in the bulk of the switch when the photoelectric thresholds required for the nonlinear switch are satisfied. According to the PACD model, the analytical expression of threshold electric field and threshold trigger optical pulse energy has been deduced. Based on the analytical expression, the thresholds of trigger optical pulse energy are calculated theoretically over the bias electric field range of 4.0–20 kV/cm. The calculation curve and the experimental results agree very well. The understanding of the photoelectric threshold characteristics helps to deepen the comprehension of the formation mechanism of the nonlinear PCSS, thus providing a theoretical basis for the application of nonlinear PCSS in the pulse power systems.