Microstructure of Stacking Fault Complex/Carrot Defects at Interface Between 4H-SiC Epitaxial Layers and Substrates

Abstract

A carrot defect with a shallow pit has been detected in a 4H-SiC epitaxial wafer using mirror projection electron microscopy inspection. The origin of the carrot defect and the microstructure of the conversion point at the interface between the epitaxial layer and the substrate were investigated using transmission electron microscopy and high-resolution scanning transmission electron microscopy. We found that two types of threading edge dislocations (TEDs) in the substrate, with ${\varvec b} = 1/3\left[ {\bar{2}110} \right]$ and ${\varvec b} = 1/3\left[ {\bar{1}\bar{1}20} \right]$, generated the carrot defect with a shallow pit in the epitaxial layer. The two TEDs converted to basal plane dislocations (BPDs) at the conversion point. Furthermore, one of the two BPDs led to the pair generation of a threading dislocation running to the epi surface and four partial dislocations propagating on each basal plane. The other BPD joined one of the four partial dislocations at the conversion point; this merged dislocation was assumed to cause a prismatic stacking fault.