The lifetime of an opposed-contact vanadium-compensation semi-insulating 4H-silicon carbide (VCSI 4H-SiC) photoconductive semiconductor switch (PCSS) was investigated. The experimental setup involved a laser wavelength of 532 nm, a bias voltage of 19 kV, and a maximum photocurrent of 200 A. After 678 high power switching cycles, the 4H-SiC PCSS was fragmented along two crystal planes. The simulation of electric fields near the electrodes is on the order of the theoretical critical breakdown field strength of SiC. Due to the distribution of the electric field, the ionization rate at the edge of the electrodes is comparatively high. Scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) were used to analyze the cross-sectional morphology and elemental characteristics of the fragments. It was found that there was only carbon phase but no silicon phase near the electrodes. The simulation results show that the maximum temperature of the device is 1865 K, which is lower than the gas phase temperature of silicon atoms in silicon carbide. During the pinch process, the carrier density increases due to the shrinking of the current channel radius, which increases the temperature of the device. When the current density is 2.73 $\times $ $\text{10}^\text{5}\, \text{A}/\text{cm}^\text{2}$ , the device temperature increment can reach 2546 K. Furthermore, the corresponding parameters are $\textit{r}/\textit{r}_\text{0}$ $=$ 0.86 and $\textit{t}/\textit{t}_\text{0}$ $=$ 0.94 in the pinch effect process. The difference in thermal expansion coefficient and elastic modulus between the metal electrode and SiC substrate, as well as the difference in temperature between materials, lead to the greatest thermal stress near the electrodes, which is confirmed by the cracks at the edge of electrodes.

The performance of an opposed-contact 4H-SiC photoconductive switch under various optical triggering modes was systematically investigated. Experimental results indicate that under a 7-kV bias voltage and an incident optical energy of 1.16 mJ, side-gap illumination achieves a peak output voltage of 2.63 kV, exceeding that of side-electrode and front illumination modes by factors of 3.37 and 1.55, respectively. Optical property measurements reveal a refractive index of 2.6518 and an extinction coefficient of ${3.22}\times {10}^{-{6}}$ at a wavelength of 532 nm, as determined by a spectroscopic ellipsometer and an ultraviolet-visible spectrophotometer. Simulations further demonstrate that the optical power distribution at the electrode edges exhibits a ratio of 1.35, while the number of photogenerated carriers under side-gap illumination reaches ${2.84} \times {10}^{{14}}$ . Moreover, the device exhibits outstanding durability, operating reliably for over 100000 switching cycles without observable degradation. These results highlight the superior performance and long-term stability of side-gap illumination as an effective triggering mechanism for high-power photoconductive switching applications.

In this paper, a physics-based ANN assisting method for extracting transient properties of extrinsically triggering photoconductive semiconductor switches (ET-PCSSs) is proposed. It exploits the nonlinear mapping of ANN between transient current (input) and doping concentration (output). According to the basic laws of photoelectric device operating, two types of ANN models are constructed by gaussian and polynomial fitting. The mean absolute error (MAE) of forecasting transient photocurrent can be less than 10 A under low triggering optical powers, which verifies the feasibility of ANN assisting TCAD applied to PCSSs. The results are comparable to computation by Mixed-Mode simulation, yet even thousands of seconds of CPU runtime cost are saved in every period. To improve the robustness of the Poly-ANN predictor, Bayesian optimization (BO) is implemented for minimizing the curl deviation of photocurrent-time curves.

The unavoidable defects in SiC materials often create deep-level traps within the bandgap, leading to deviations from the ideal state in the current–voltage characteristics of devices due to space-charge effects. For optically driven photoconductive semiconductor switches (PCSSs), the incorporation of optoelectronic coupling complicates current transport mechanisms, as both photoinjected and electrically injected nonequilibrium carriers interact simultaneously. This work reveals the filling dynamics of acceptor-type traps in 4H-SiC under dual carrier injection and proposes a novel light-compensated-trap (LCT) mechanism, which modifies the traditional space-charge-limited current (SCLC) model. The technology computer-aided design (TCAD) method is used to visualize the evolution of space charge under illumination, intuitively explaining the LCT effect. A revised SCLC model incorporating light intensity is established, and the quantitative relationship between light effect and voltage under varying trap distributions is analyzed.

This study reports an initial investigation of the performance and damage mechanisms in Fe: $\boldsymbol {\beta }$ -Ga₂O₃ photoconductive switches fabricated on (100), (010), and (001) crystal planes. The devices achieved a maximum conduction voltage of 25 kV; however, significant performance variations were observed across different crystal orientations under identical fabrication and testing protocols. Failure analysis indicates that the inherent cleavage properties of $\boldsymbol {\beta }$ -Ga₂O₃ are a major contributor to device damage. These findings collectively demonstrate that crystal plane selection is a critical factor governing the performance of Fe: $\boldsymbol {\beta }$ -Ga₂O₃-based photoconductive switches.