Growth kinetics,structure and surface morphology of AlN/α-Al2O3 epitaxial layers

The gas-phase epitaxy of AlN on saphire substrates in the system Al HCl NH₃–Ar was investigated. The uniformity and structural perfection of the layers were shown to be determined by gas dynamics in the growth zone. The growth rate of AlN-layer is proportional to AlCl concentration in the growth zone and does not depend on NH₃ partial pressure. This is in accordance with the law of diffusional stoichiometry. The morphology of AlN-layers was shown to be dependent on the growth rate and the substrate orientation. Smooth mirror-like layers were prepared on the sapphire planes (0001) and (1120) at low growth rates. X-ray microanalysis showed the oxygen impurity content at the level 1 — 5 · 10²¹ cm⁻³. Other impurities were not available.