N. Fujimoto

Microstructure of epitaxial lateral overgrown AlN on trench-patterned AlN template by high-temperature metal-organic vapor phase epitaxy

A high-quality thick AlN layer without cracks was grown on sapphire by the combination of the high-temperature metal-organic vapor phase epitaxial growth and epitaxial lateral overgrowth methods. The dislocation behavior and growth mode of AlN are investigated in detail. The dislocation density of the AlN layer thus grown was less than 107cm−2.

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 3×108 cm-2.

Dislocations in AlN 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 °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.

Thermodynamic Aspects of Growth of AlGaN by High-Temperature Metal Organic Vapor Phase Epitaxy

The metalorganic vapor phase epitaxial (MOVPE) growth of AlGaN on AlN-coated sapphire at a temperature higher than 1,200 °C was carried out. Compared with that at a low-temperature growth regime in which alloy composition is determined by the flow rates of metalorganic Ga and Al sources, the solid composition of AlGaN is found to be strongly affected by thermodynamics.