Sublimation growth of aluminum nitride-silicon carbide alloy crystals on SiC(0001) substrates

Thick (up to 1 mm) AIN-SiC alloy crystals were grown on off-axis Si-face 6H-SiC (0001) substrates by the sublimation-recondensation method from a mixture of AIN and SiC powders at 1860-1990 degrees C in a N-2 atmosphere. The color of the crystals changed from clear to dark green with increasing growth temperature. Raman spectroscopy and x-ray diffraction (XRD) confirmed an AIN-SiC alloy was formed with the wurtzite structure and good homogeneity. Three broad peaks were detected in the Raman spectra, with one of those related to an AIN-like and another one to a SiC-like mode, both shifted relative to their usual positions in the binary compounds, and the third broad peak with possible contributions from both AIN and SiC. Scanning Auger microanalysis (SAM) and electron probe microanalysis (EPMA) demonstrated the alloy crystals had an approximate composition of (AIN)(0.75)(SiC)(0.25) with a stoichiometric ratio of AI:N and Si:C. The substrate misorientation ensured a two-dimensional growth mode confirmed by scanning electron microscopy (SEM).