Impact of impurities in 4H, 6H and 3C-SiC substrate on reverse recovery time of p-n junction

Short reverse recovery time of a p-n junction is critical for high speed semiconductor device operation. This time period is a result of recombination processes when a p-n junction is switched from forward bias to reverse bias. Minority carrier lifetime is the major parameter determining the duration of reverse recovery. Three main poly-types of Silicon Carbide (SiC) including 4H-SiC, 6H-SiC and 3C-SiC were examined. Vanadium impurity defects in three SiC poly-types are considered with fixed capture cross section and defect density. Vanadium has deep level defect states in SiC and as such is active as a recombination center. The study finds that reverse recovery time depend not only on the ratio between the magnitude of forward and reverse current, but also on temperature and the comparison between forward voltage versus the gap between the impurity level and the middle of band gap.