Pulsed Power Switching of a 4 MM × 4 MM SIC Thyristor

While silicon carbide (SiC) is beginning to make its way into the low voltage (300-1200 V) commercial power diode market, its capabilities in pulse power applications have yet to be proven. A previous investigation by the U.S. Army Research Laboratory (ARL) of SiC GTOs suggested that this emerging technology could provide pulsed current densities 40 to 60 times greater than is obtainable in silicon-based switches [1]. This study continues that earlier work by examining 4 mm times 4 mm 4H-SiC thyristors designed by CREE Inc. to reach 1 kV and 4 kA. These devices were successfully switched up to 3.89 kA with a current density reaching 56.1 kA/cm
²
, a specific rate-of-current-rise of 49 kA/mus/cm
²
(for peak rise-time 7.8 kA/mus) and a pulse-width ranging from 2.0 mus to 2.6 mus. The thyristors were tested at both single shot and repetitive switching rates up to 5 Hz. Device characteristics were mapped on a curve tracer at different stages of testing, and the failure of each thyristor was analyzed.