Performance of a Vertical 4H-SiC Photoconductive Switch With AZO Transparent Conductive Window and Silver Mirror Reflector

A new vertical geometry photoconductive switch device based on vanadium compensated 4H Silicon Carbide (4H-SiC) is presented with the structure of aluminum doped ZnO (AZO) transparent conductive window on the top of 4H-SiC and a silver mirror reflector on the backside. For this new structure, laser can trigger the device convenientlyby irradiate the electrode face directly. A circuit without load resistor is used to test the performance of device, and a switch is triggered by Nd:YAG 532-nm laser (10-ns full-width at half-maximum). Results show that the minimum on-state resistance is 7.5 Ω at an illumination density of 18.2 MW/cm
²
, and the breakdown voltage is 12 kV (breakdown electric field is 260 kV/cm). In particular, the optical utilization efficiency of laser energy and the minimum on-state resistance performance are significantly improved in this new vertical geometry photoconductive switch by the AZO film and mirror reflector.