The role of micropipes in pore formation in SiC crystals with foreign polytype inclusions was studied by means of synchrotron phase sensitive radiography, optical and scanning electron microscopy, and color photoluminescence. The pores at the inclusion boundaries were revealed, and their shapes and locations were analyzed. It was found that the pores arose due to the attraction of micropipes by the foreign polytype interfaces, followed by micropipe coalescence. The observed pores had tubular or slit shapes. Tubular pores nucleated at the inclusion corners, where the inclusion-associated stresses were concentrated. Slit pores spread between them and followed the shape of the inclusion boundaries. The observation were within a 2-dimensional model, of elastic interaction between micropipes and inclusion boundaries, which accounted for the free surfaces of micropipes.

Role of Micropipes in the Formation of Pores at Foreign Polytype Boundaries in SiC Crystals. M.Y.Gutkin, A.G.Sheinerman, T.S.Argunova, J.M.Yi, J.H.Je, S.S.Nagalyuk, E.N.Mokhov, G.Margaritondo, Y.Hwu: Physical Review B, 2007, 76[6], 064117 (9pp)