A study of the initial stage of AIN growth on SiC substrate by the sublimation re-condensation technique was undertaken to understand the origin of crystal defects in bulk AIN crystals. When SiC was used as a seed crystal the AIN crystals did not completely coalesce, and individual grains were observed. Such crystal growth features were determined by the initial nucleation of the crystals. in this study, the nucleation of AIN on 6H-SiC(0001) was investigated by Scanning Electronic Microscopy (SEM), S-4700 Hitachi, and Electron Backscattered Diffraction (EBSD), Thermo Noran Phase ID.
At high temperatures (>1800°C) in the presence of AIN, the surface of the SiC substrate first decomposed along remnant polishing scratches[l], ultimately leaving hexagonal hillocks; simultaneously, the AIN nucleated on these SiC hillocks. Surprisingly, the AIN nuclei appeared out of alignment with the underlying SiC hillocks. By measuring several points from the SEM image (figure 1), this misorientation is in the range of 15° to 30°.