Formation and multiplication of basal plane dislocations during physical vapor transport growth of 4H-SiC crystals

The distribution of basal plane dislocations (BPDs) in physical vapor transport (PVT) grown 4H-SiC crystals has been investigated using Raman microscopy and X-ray topography. X-ray topography observations of (1 1 2¯ 0) wafers vertically sliced along the growth direction from the crystals revealed that there existed almost periodically arranged layers with a high density of BPDs (bunched BPDs) in PVT-grown 4H-SiC crystals. These layers were characterized using Raman microscopy and high resolution X-ray diffraction, and it was found that large tensile and compressive stresses were associated with the layers. The stresses showed characteristic variations along the basal plane as well as the growth direction. Based on these results, the formation and multiplication processes of BPDs during PVT growth of 4H-SiC crystals are elucidated.