ON-State Characteristics of a High-Power Photoconductive Switch Fabricated From Compensated 6-H Silicon Carbide

The ON-state characteristics of a 6-H silicon carbide (SiC) photoconductive switch with vertical geometry, transverse illumination, and linear-mode operation are presented. The switch is triggered by an optical source with a photon energy that is less than the bandgap energy of SiC. Following low-power matching characteristics, the analysis of a design incorporating and layers next to the cathode shows higher hold-off voltage with an improved ON-state response mechanism. The p-layered photoconductive semiconductor switch (PCSS) can be operated at a maximum field of 875 kV/cm, whereas the n-layered PCSS, which is operating at a slightly lower field, shows higher current carrying capabilities. Higher current for the n-layer PCSS can be attributed to the nature of the region adjacent to the cathode. In the p-layered PCSS, this region inhibits an initial hole collection, thus decreasing the collected charge. In addition, a kink during the initial collection for the p-layered PCSS could influence the rise time when operating beyond 35-kV bias.