Ultrafast 10kV SiC PCSS and its on-state Characteristics

Summary form only given. Vertical geometry PCSSs (Photoconductive Semiconductor Switches) with opposing electrical contacts were fabricated using 0.4mm thick, vanadium compensated, semi-insulating, 6H-SiC (Silicon Carbide) “c”-plane wafer. Ultrafast photocurrent waveforms were obtained when the switches were illuminated laterally by <100 ps pulse width, 1064nm wavelength laser. The risetimes, falltimes, and widths of photocurrent waveforms are all ∼1ns. The ultra fast characteristics of the SiC PCSSs can be owned to the very short carriers lifetime of the SiC crystal. The SiC PCSSs were tested up to a bias voltage of 11 kV with the corresponding peak current is 90 Amperes. The 6H-SiC PCSS chips can withstand average electric field up to 27.5kV/mm. This value though is much lower than the theory breakdown electric field of 300kV/mm, but is much higher than one (∼3kV/mm) of earlier designed lateral geometry surface SiC PCSS. One reason is that, present opposing-electrical-contacts design is out of enormous electric distortion of opposing blade electrodes in lateral geometry surface switches, and prohibits surface flashover. Another reason can be attributed to that the small area electrodes design can avoid micropipe defects, which are vertical to and penetrate “c”-plane wafer, then tend to lead early breakdown. The minimum on-state resistance of about 21Ω was obtained with ∼2mJ triggering laser energy.