Identification of dislocations in 4H-SiC epitaxial layers and substrates using photoluminescence imaging

Dislocations in n- and p-type substrates as well as in epitaxial layers (epilayers) were clearly identified using a photoluminescence (PL) imaging technique. Dislocations in epilayers show large/small bright spots or lines in infrared PL images, which correspond to threading screw/edge dislocations (TSDs/TEDs) or basal plane dislocations (BPDs), respectively. In contrast, dislocations in substrates exhibit large/small dark spots or dark lines in infrared PL images, corresponding to TSDs/TEDs or BPDs, respectively. These different features (bright/dark contrast) of dislocations may originate from the different densities of point defects or impurities.