Safe Operating Area and Long-Term Reliability of 9-kV Silicon Carbide PNPN Super Gate Turn-Off Thyristors

One of the major requirements for adoption of new silicon carbide (SiC) super gate turn-off thyristors (SGTOs) into high-energy applications is to verify the safe operating area and long-term reliability capabilities of these devices. In this letter, we have developed a unique high-energy testing system that can evaluate the performance limitations with respect to lifetime capabilities of the 9 kV, 1 cm(2), SGTOs at ultrahigh pulsed current levels from 1 to 3.5 kA. The test system produces square current pulses with a user specified current amplitude and a 100-mu s pulsewidth at a maximum repetition rate of 1 shot/s (>0.1% duty cycle). A lifetime safe operating area with respect to maximum pulsed current was then established that these 1 cm(2), 9 kV, SiC SGTOs can perform reliably without significant degradation at pulsed current levels up to 2.0 kA. At current levels above 2.0 kA shifts in the on-state voltage are observed probably due to device over-heating at such high current levels and having not enough time to fully dissipate the heat between any two shots, which results in the device rapidly deteriorating due to increased on-state losses ultimately leading to premature failure.