Conversion of basal plane dislocations to threading edge dislocations in growth of epitaxial layers on 4H-SiC substrates with a vicinal off-angle

摘要

We have investigated a conversion of basal plane dislocation (BPD) to threading edge dislocation (TED) in growth of epitaxial layers (epi-layers) on 4H-SiC vicinal substrates with an off-angle of 0.85° at low C/Si ratio of 0.7 by using deep KOH etching and X-ray topography observations. Deep KOH etching indicated that BPDs in the substrates converted to TEDs in the epi-layers. X-ray topography observations suggested that the conversion occurred during epitaxial growth when the thickness of epi-layers was less than 1.5 μm. We found that the conversion ratio obtained from counting deep KOH etch pits was over 99%.