Characterization of comet-shaped defects on C-face 4H-SiC epitaxial wafers by electron microscopy

The crystallographic structures of comet-shaped defects observed on the C-face 4H-SiC epitaxial film were investigated using electron microscopy. The comet-shaped defects consist of head and tail parts. The tail part is symmetric with respect to the (11¯00) plane in the cross-sectional image and narrows along the [1¯1¯20] direction, i.e., along the step-flow direction of epitaxial film growth on the C-face. The tail part consists of four 3C domains with characteristic twin boundaries of Σ3 and Σ27. The head part is formed by 3C and defective hexagonal-SiC polycrystalline grains during epitaxial film growth.