Impacts of recombination at the surface and in the substrate on carrier lifetimes of n-type 4H-SiC epilayers

The impacts of carrier recombination at the surface as well as in the substrate are examined by using numerical simulation based on a diffusion equation. The simulation has shown that a very thick epilayer is needed for accurate measurement of carrier lifetimes of n-type 4H-SiC epilayers if the bulk lifetime in the epilayer is longer than several microseconds, due to the extremely short lifetimes in the substrate.