Pulse Evaluation of High Voltage SiC Diodes

Summary form only given. The U.S. Army Research Laboratory is evaluating silicon carbide semiconductor components to determine the range of high power and pulsed power applications for which SiC is a sensible material to use. With SiC´s tolerances for high temperatures and high current densities, compact modules of SiC diodes might be ideal for protecting other high power circuit components under pulse conditions. This study evaluated SiC diodes with a footprint of 0.73 cm² which were designed bv Cree, Inc. and packaged and pulse tested at ARL. The diodes are rated for 6 kV blocking and 50 A of continuous forward current. They were arranged to clamp reverse currents at the switching end of a large capacitor bank and were pulsed at a single shot rate both individually and in parallel. Individual diodes were pulsed as high as 5.9 kA (corresponding to an action of 4.5 times 10³ A²s) for 25 single shots before failing, and as high as 5.0 kA (with an action of 3.5 times 10³ A²s) for over 100 shots without failure. Groups of diodes were characterized on a curve tracer and matched based on on-state dV/dl slope, which ranged from 3.7-4.0 mOmega. Five diodes paralleled in the pulse testbed carried a total current of 23 kA with each diode sharing 19-21% of the total peak current. Modules consisting of 8-10 diodes in parallel will be similarly pulsed to reach a peak total current of 40 kA and will ultimately be combined in a single, compact package for higher current applications.