Performance and characterization of a 20 kV, contact face illuminated, silicon carbide photoconductive semiconductor switch for pulsed power applications

A 20 kV, lateral geometry, contact face illuminated, silicon carbide (SiC) photoconductive semiconductor switch (PCSS) is presented. The SiC PCSS was fabricated from high purity semi-insulating, bulk 4H-SiC (12.7 mm × 12.7 mm × 0.35 mm), in a lateral geometry, (0.6 mm gap) with both the anode and cathode contacts located on the same face of the device. The device was illuminated with light from a tripled Nd:YAG laser (355 nm-7 ns FWHM) entering from the contact face. The device demonstrated sub-ohm on-state resistance for laser pulse energies in the mJ range, and micro-amp leakage currents at 20 kVdc in the off-state. Voltage hold-off and low leakage currents in the off state were achieved through high energy electron beam irradiation of the bulk material. The switch's geometry and packaging are discussed, along with experimental switching and blocking characteristics.