Measurements and simulations of self-heating and switching with 4H-SiC power BJTs

Transient measurements and device simulations were performed to investigate self-heating and switching with 4H-SiC BJTs. A current gain decrease was found during self-heating presumably due to reduced electron mobility with increasing temperature. Surface recombination increased the simulated maximum temperature but the current gain decrease during self-heating was similar as for bulk recombination. A fast switching of 0.5 A and 200 V was shown with a voltage rise-time of about 70 ns and fall-time of 50 ns. Turn-off measurements show a noticeably delay time before fall-off of the emitter current, indicating a significant amount of stored carriers in the base.