Report on the growth of bulk aluminum nitride and subsequent substrate preparation

High-quality, bulk aluminum nitride crystal grains exceeding 1 cm in dimension have been obtained using a self-seeded sublimation-recondensation growth technique at 0.9 mm/h driving rate. X-ray double crystal diffraction and topography show a full-width-at-half-maximum of around 100 arcsec and extensive areas with a density of dislocations less than 10⁴ cm^-2, respectively. These substrates have been prepared by chemical mechanical polishing techniques to obtain a surface roughness of 1.4-1.6 nm. The size, structural quality, and surface roughness prove these substrates to be adequate for III-nitride device fabrication.