Crystal growth of mixed AlN–SiC bulk crystals

Bulk AlN–SiC mixed single crystals are prepared by sublimation growth employing pure AlN or mixed AlN–SiC sources and 6H-SiC seed crystals. As the growth temperature is increased from 1900 to 2050 °C, using seeds with different off-axis orientations, inclined up to 42° from the basal plane toward the (0 1 –1 0)-plane, or using different source materials, crystals with different Si/C contents are obtained. Dependent on the Si and/or C content, crystal coloration changes from yellowish to greenish to blackish. Modification in crystals’ coloration and corresponding changes in below band-gap optical absorption and cathodoluminescence spectra are discussed.