Characteristics of photo-activated avalanche charge domain in semi-insulating GaAs photoconductive switch

According to the photo-activated charge domain theoretical model, the formation characteristics of the photo-activated avalanche charge domain (PAACD) is studied based on the characteristics of the photoelectric thresholds for the high-gain GaAs photoconductive semiconductor switch (PCSS). It is shown that the PAACD with a peak electric field much larger than the intrinsic breakdown electric field of GaAs will be formed within the switch at the instant of optical triggering, and the triggering optical wavelength and spot size have a significant effect on the initial domain characteristics. According to the PAACD model, the dependence of the threshold electric field on threshold laser pulse energy (TLPE) is calculated theoretically. Quantitative agreement between the calculation and the experiment has been achieved. Using the Silvaco software, the transport process of the PAACD is investigated numerically. Moreover, the variations of TLPE with laser spot size under different bias electric fields are studied theoretically. Our study can deepen the understanding of the generation mechanism of high-gain GaAs PCSS and contribute to the optimization of the device's performance.