Defect reduction with quantum dots in GaN grown on sapphire substrates by molecular beam epitaxy

The GaN films grown on buffer layers containing quantum dots by molecular beam epitaxy on sapphire substrates were investigated. The density of the dislocations in the films was determined by wet chemical etching and atomic force microscopy. It was found that the insertion of a set of multiple GaN quantum-dot layers in the buffer layer effectively reduces the density of the dislocations in the epitaxial layers. As compared to the dislocation density of ∼1010 cm−2 in the typical GaN films grown on AlN buffer layer, a density of ∼3×107 cm−2 was demonstrated in the GaN films grown with quantum dot layers.