The propagation of basal-plane dislocations from off-axis 4H-type carbide substrates and into homo-epitaxial layers was investigated by using chemical etching, optical microscopy and transmission electron microscopy. The etch-pit densities of threading edge and basal-plane dislocations changed significantly across the epilayer/substrate interface. The conversion of basal plane dislocations, in the substrates, into threading edge dislocations in the epilayers was observed. Transmission electron microscopic observations revealed that the threading dislocations in the epilayers were inclined away from the c-axis and towards the down-step direction. The conversion was interpreted as being a result of the image force in the epilayers between flowing growth steps and basal-plane dislocations. This effect could lead to an apparent improvement in the structural quality of epilayers as compared to that of substrates.

Dislocation Conversion in 4H Silicon Carbide Epitaxy. S.Ha, P.Mieszkowski, M.Skowronski, L.B.Rowland: Journal of Crystal Growth, 2002, 244[3-4], 257-66