Structural transformation of lattice defects in free-spreading growth of bulk SiC crystals

Using synchrotron X-ray topography and phase-contrast imaging, we investigated lattice defects in bulk SiC crystals grown by physical vapor transport in a free spreading condition. We find that polytype inclusions appearing at initial growth stage are overgrown by the matrix, making pores which are then transformed into micropipes with a low density of 10 cm−2, in particular, in the lateral region. We propose that complex planar defects configured from dislocations and micropipes are transformed into slit pores via vacancy-diffusion and micropipes-attraction mechanisms. Our finding suggests that suppression of the nucleation of foreign polytype inclusions is a key approach for providing high quality free spreading SiC growth.