A dynamically reduced breakdown voltage from more than 2 kV under static conditions to 300 V during reverse recovery was measured for 4H-SiC p(+)nn(+) diodes. Device simulation indicates that deep hole-trapping donors in the n-base, close the pn junction, could explain the dynamically reduced breakdown voltage. Hole traps situated 0.66 eV above the valence band were found in the diode n-base by DLTS measurements.