Investigation on small growth pits in 4H silicon carbide epilayers

Using a polarized light microscope (PLM) and AFM, various growth pits associated with crystallographic defects in 4H silicon carbide (SiC) epilayer have been extensively investigated. Defects, including screw dislocations, grain boundaries, and edge dislocations, open growth pits of various shapes in the SiC epilayer surface. For the investigated high-quality commercial SiC wafers, the relationship between crystallographic defects and various growth pits has been established. In 10-μm-thick epilayers, the previously reported small triangular growth pits can be further classified into growth pits with or without nano-cores. The growth pits with nano-cores are associated with screw dislocations while the growth pits without nano-cores are mainly observed in the highly stressed regions of the crystal. The grain boundaries result in growth-pit arrays, while the edge dislocations lead to shallow stripe-shaped growth pits in 10-μm-thick epilayers and growth pits with small nano-cores in 100-μm-thick epilayers. The possible influence of sharp-apex growth pits on SiC device performance has also been discussed in this study.