Characterization of horseshoe-shaped defects in 4H-SiC thick homoepitaxial layers

We report horseshoe-shaped protuberance defects encountered in growing thick homoepitaxial films on 4 degrees off caxis 4H-silicon carbide substrates. Their morphology, polytype and formation mechanism are investigated by optical microscopy, laser microscopy, micro-Raman spectroscopy, micro-photoluminescence spectroscopy and defect tracking experiments. The defects are observed to protrude from the surrounding area with a facet of (0001) at an angle of about 3.06 degrees. Concomitantly, surface undulations develop and extend about hundreds of microns from the defect perpendicular to the direction of step flow. No polytype inclusions are found in these defects. The defect tracking reveals that the defects are not directly related to the existence of dislocations. We think that the formation of the defects origin from the occurrence of giant step bunching and subsequent faceting.

Automated summary

We report the discovery of horseshoe-shaped protuberance defects during the growth of thick homoepitaxial films on 4 degrees off caxis 4H-silicon carbide substrates. Through various experimental techniques, we investigated the morphology, polytype, and formation mechanism of these defects. Our findings suggest that these defects protrude from the surrounding area with surface undulations, but do not contain polytype inclusions. The defect tracking experiments reveal that the defects are not directly related to the presence of dislocations.