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.

The switching transient of gallium arsenide photoconductive semiconductor switch (GaAs PCSS) undergoing the transition from linear mode to nonlinear mode is investigated based on a “two-channel” model. Excellent agreement between the simulated and the experimental output waveforms is achieved first in the study of this transitional mode. The numerical results have revealed that a competitive relationship exists between the switching and nonswitched channels of the PCSS, and the formation and evolution of avalanche domains boost the nonlinear mode developing in the switching channel to win out from the linear mode dominated by the nonswitched channel. Based on the numerical model, the effects of the cross section of current channel on the output characteristics are well analyzed and discussed, which have also been demonstrated experimentally.

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.

In this work, the controllable current diversion based on the inductance modulation has been demonstrated on a two-channel bulk gallium arsenide (GaAs) photoconductive semiconductor switch (PCSS) array. It is found that the additional inductances can regulate the switching speed of each PCSS in the array, then play positive roles in improving the current-sharing effect and sustaining the stability of switching current through the array during consecutive shots. The theory of multiple avalanche domains is introduced to interpret the modulation mechanism by performing a 1-D simulation, and has revealed that the switching speed is essentially determined by the evolution rate of avalanche domains influenced by the dynamic voltage division process, which is modulated by the additional inductances.

A ceramic-based pulse-forming line (PFL) is a solid-state device with a wide range of applications in compact pulsed power systems. In this paper, the characteristic impedance of a ceramic-based PFL is theoretically analyzed, and an improved PFL based on an impedance matching electrode is proposed. The improved PFL effectively increases the flat-top ratio and reduces the rise and fall times, enhancing its potential applicability. Experiments using the improved PFL show that, under a charging voltage of 33 kV and with an impedance matching load, the output pulse width can reach 86 ns with a matching impedance of 3.9 Ω. The improved PFL output waveform has a flat-top ratio that reaches 72%, compared with 49.5% in a typical PFL, and exhibits shorter rise and fall times.

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.