Origin of Double-Rhombic Single Shockley Stacking Faults in 4H-SiC Epitaxial Layers

We have investigated double-rhombic single Shockley stacking faults (DRSFs) in 4H-SiC epitaxial layers by analyzing structural details. A combination of plan-view transmission electron microscopy (TEM) and cross-sectional high-angle annular dark field scanning TEM made it possible to determine the Burgers vectors of partial dislocations that consist of DRSF boundaries and the type of glide of the original basal plane dislocations (BPDs). From these results, the origins of DRSFs were identified as BPDs that originated as 60-degree perfect dislocations, and the inclination of the DRSFs was found to depend on the Burgers vectors and the type of glide of the original BPDs. Also, the configuration of the accompanying threading edge dislocations (TEDs) at both ends of the BPDs was categorized into two types, namely (1) TEDs at both ends of the BPD segments toward the surface of the epitaxial layer (cis-configuration) which form the half-loop arrays, and (2) a TED at one end of the BPD from the deeper side of the epitaxial layer and another toward the surface of the epitaxial layer (trans-configuration), and the original BPD segments were isolated. The shrinking processes of the DRSFs were also examined, and it was found that they were not a reversal of the expansion process.