Mechanism of conversion and propagation of dislocations in 4H-SiC epilayer

The elastic energies of four kinds of dislocations per unit growth length have been calculated. We propose that threading screw dislocations(TSDs) along ≪0001≫ can propagate into epilayer but can not convert to TEDs. We suggest that both basal plane mix dislocations(BMDs) and threading screw dislocations (BTSDs) can convert to TEDs, and BMDs convert to TEDs much easier than BTSDs in epilayer because of the higher elastic energy. Based on the experimental results, the relationship between the dislocation density and the conversion and propagation of dislocations is discussed.