The properties of switching transient in the gallium arsenide photoconductive semiconductor switch (GaAs PCSS) are significant for improving the device lifetime. In this article, the properties of switching transient in the opposed-contact semi-insulating (SI) GaAs PCSS, including the physical process of the ultrafast switching, the characteristics of delayed breakdown, and the current density distribution, are studied, based on an effective 2-D, time-dependent numerical model. The numerical results demonstrate that there exists a positive feedback loop between the increase of the carrier density and the formation and evolution of the avalanche domains, which achieves the ultrafast switching of the opposed-contact SI-GaAs PCSS. The higher bias voltage and triggering optical intensity can promote the earlier formation of the avalanche domains and accelerate the evolution of the domains, leading to a shorter delay time and switching time. The triggering positions determine the distribution of the avalanche domains in the opposed structure, affecting the delay time, among which the cathode triggering leads to the shortest delay time. Current crowding in the opposed structure mainly occurs in the vicinity of the contacts, which first damages the edges of the contacts and makes the areas near the contacts present different failure characteristics. Our analysis indicates that anode triggering is effective for suppressing the current crowding to improve the lifetime of the opposed-contact PCSS.

We demonstrate the positive role of an optical internal reflection structure (OIRS) in improving the on-state performances of gallium arsenide photoconductive semiconductor switch (GaAs PCSS). Herein, the structure consisting of a convex lens and two reflectors creates an effect of increasing the extrinsic absorbance. Under the same laser input, the PCSS employing this structure has achieved higher voltage output, faster switching and lower on-state resistance, which demonstrates at least 1.5-fold improvement in triggering efficiency, compared to the normal device. A two-dimensional (2D) device simulation has been performed and reveals that the positive effect of the OIRS is attributed to the accelerated formation of avalanche domains and the heightened carrier concentration, which are affected by the increased optical absorption.

The stability of synchronous operation is directly related to the time jitter of the gallium arsenide photoconductive semiconductor switch (GaAs PCSS). In this work, a numerical model for the switching jitter of avalanche GaAs PCSS is established, and the impacts of triggering optical energy and bias electric field on the switching jitter are investigated numerically based on an equivalent bulk current channel. The proposed numerical model predicts well the changing characteristics of switching time as well as switching jitter, which has been demonstrated by the experimental results. On this basis, the theory of multiple avalanche domains is introduced to compare the domain evolutions influenced by the bias electric field and triggering optical energy. The results indicate that the reduction of switching jitter is significantly determined by the accelerated formation and evolution of avalanche domains, which provides a good explanation of the jitter mechanism of switching time.

The planar solid-state pulse-forming line (planar solid-state PFL) is an important solid-state device used in compact pulse power systems. Moreover, pulsed power systems constitute a crucial element within electroporation systems. In this paper, we present theoretical and simulation analyses of the influence of the ground electrode structure of the planar solid-state PFL on the edge electric field and thermal distribution of high-voltage electrodes and the design of a novel improved solid-state PFL (opposite-electrode PFL) that differs from the classic planar solid-state PFL (full-electrode PFL) in which the ground electrode covers the entire plane. The ground electrode of the opposite-electrode PFL is structured to be consistent with the high-voltage electrode and positioned directly opposite to enhance the withstand voltage capacity of the planar solid-state PFL. The simulation results show that when the ground electrode width is the same as the high-voltage electrode, the electric field strength at the edge of the electrodes is smaller. In the electrostatic field simulation, the edge electric field strength of the high-voltage electrode in the opposite-electrode PFL is smaller than that of the full-electrode PFL, which indicates that the opposite-electrode PFL may have a higher withstand voltage. The experimental results show that the opposite-electrode PFL has a higher withstand voltage than the full-electrode PFL, which verifies the correctness of the theoretical and simulation analyses. Furthermore, the opposite-electrode PFL surface temperature rise showed a better performance after running the same test repeatedly. The findings of this study are conducive to enhancing the maximum output voltage or compactness of pulsed power systems and highlight the additional potential for the utilization of solid-state pulse generators in electroporation systems.