Evaluation of 4 mm x 4 mm Silicon Carbide Thyristors

The U. S. Army Research Laboratory (ARL) is evaluating silicon carbide thyristors to determine the extent of silicon carbide capabilities as a possible replacement for silicon in future pulsed switching applications. Individual SiC die measuring 4 mm x 4 mm were pulsed at high temperatures and varying pulse widths. At 150 degC, these thyristors were switched in an RLC circuit up to 3.2 kA and repetitively pulsed at 2.6 kA and 5 Hz for greater than 14,000 pulses. A pulse forming network (PFN) was designed to increase the pulse width and the action seen by the SiC devices. At ambient temperature and a peak current of 2 kA, SiC thyristors were switched in the PFN at a 50% pulse width of 40 mus and an action of 150 A
²
s. These devices were also pulsed at narrower pulse widths in pairs to look at their behavior in parallel. One pair reached a peak total current of 6.7 kA with current sharing as good as 51% / 49%. This paper includes further data on the three aforementioned test procedures, as well as analysis of the devices' failure points.