If the drive gate voltage while ON is less than 15V it may be impossible to maintain ON operation, and when less than 14V the temperature characteristics of the ON resistance will change from positive to negative. As a result, the ON resistance will decrease at high temperatures, increasing the risk of thermal runaway. Therefore, please ensure that the voltage is greater than 15V. ROHM's TZDB series features a withstand voltage greater than 40V, preventing gate breakdown and ensuring worry-free operation. However, continuing to provide more than the rated voltage (-6V/+22V) will gradually change the threshold value due to the effects of the traps that exist on the gate oxide film interface. However, because the effects from threshold voltage fluctuations during momentary voltage surges (under 300nsec) are small, the acceptable range is actually -10V to +26V.
The bandgap of SiC is 3x that of silicon, resulting in a 3V larger rise voltage in the pn diode and consequently a relatively large forward voltage drop. However, since reverse conduction in the bridge circuit etc. is possible due to gate ON signal input during commutation, substantive steady-state loss should not be an issue.