Dislocations in AIN epilayers grown on sapphire substrate by high-temperature metal-organic vapor phase epitaxy

The growth temperature of AlN layers is one of the most important factors in metal-organic vapor phase epitaxy (MOVPE) growth. AlN layers were grown using our customized high-temperature MOVPE system. The crystalline quality was discussed on the basis of X-ray diffraction, atomic force microscopy (AFM) and transmission electron microscopy (TEM) measurements. The samples grown at a temperature of 1400 degrees C had much improved crystalline quality in terms of the X-ray rocking curve full width at half maximum values and AFM root-mean-square roughness. In addition, according to TEM analysis, edge type dislocations caused by small-angle grain boundaries were predominant under a low growth temperature, whereas these dislocations became much fewer with increasing growth temperature.