High-Temperature Metal-Organic Vapor Phase Epitaxial Growth of AlN on Sapphire by Multi Transition Growth Mode Method Varying V/III Ratio

High-quality AlN layers were grown on c -plane sapphire substrates by high-temperature metal-organic vapor phase epitaxy. AlN layers of about 9 µm in thickness with an atomically flat surface were obtained without cracks. Multiple modulation of the V/III ratio during growth led to a reduction in the number of dislocations during the growth transition period. The dislocation density of the AlN layers was found to be less than 3×10 8 cm -2 .