Design and Evaluation of a Compact Silicon Carbide Photoconductive Semiconductor Switch

A high-power vertical photoconductive switch was fabricated from a high-purity semi-insulating 4H-SiC wafer. The device was fabricated from an as-grown wafer with resistivity >; 10⁹ Ω · cm and had a dark resistance of greater than 6 × 10⁹ Ω. The switch was operated at 15 kV/cm and achieved a peak photocurrent of 14 A into a 25-Ω load. Optimization of the excitation wavelength and switch geometry using an optical parametric oscillator was studied in order to decrease the laser requirements for optical triggering. This has led to a decrease in ON-state resistance of almost two orders of magnitude for similar excitation energy levels at visible wavelengths. This work forms the basis for developing very compact high-voltage photoconductive switches.