Generation and Recombination Carrier Lifetimes in 4H SiC Epitaxial Wafers

Compared to silicon, there have been relatively few comparative studies of recombination and carrier lifetimes in SiC. For the first time, both generation and recombination carrier lifetimes are reported from the same areas in 20 mu m thick 4H SiC n-/n+ epi-wafer structures. The ratio of the generation to recombination lifetime is much different in SiC compared to Si. Activation energy calculated from SiC generation lifetimes shows that traps with energy levels near mid-gap dominate the generation lifetime. Comparison of both generation and recombination lifetimes and dislocation counts measured in the device area show no correlation in either case.