Structure and Morphology of Inclusions in 4° Offcut 4H-SiC Epitaxial Layers

The structure of inclusions and their influence on surface morphology, local strain, and basal plane dislocations were investigated in silicon carbide (SiC) epitaxial layers grown on 4A degrees offcut substrates. On high-resolution x-ray topography images, strain fields were observed surrounding the inclusions. Ultraviolet photoluminescence images revealed the presence of strain-induced dislocations around the inclusions. Micro-Raman and microphotoluminescence spectroscopy showed that the inclusions exhibited a complex structure that consisted of 3C polytype regions and misoriented 4H polytype regions. The resulting lattice deformation typically propagates in the step-flow growth direction and causes distorted surface morphology.