Abstract: The quenched domain mode of the photo-activated charge domain (PACD) in semi-insulating (SI) GaAs photoconductive semiconductor switches (PCSSs) is observed.We find that the quenched domain is induced by the instantaneous electric field across the PCSS being lower than the sustaining electric field of the domain during the transit of the domain.The extinction of the domain before reaching the anode can lead to a current oscillation frequency larger than the transit-time frequency when the bias electric field is lower than the threshold electric field of the nonlinear PCSS.According to the operation circuit and the physical properties of a high-field domain,an equivalent circuit of the quenched domain is presented.The equivalent circuit parameters including capacitance,resonant frequency,and inductance are calculated and measured.Our calculations agree well with the experimental results.This research provides theoretical and experimental criteria for heightening the oscillation frequency and efficiency of PACD devices.

Key words: photoconducting switch, quenched domain mode, equivalent-circuit