Films grown onto buffer layers containing quantum dots, by molecular beam epitaxy on sapphire substrates, were investigated. The densities of dislocations in the films were determined by using wet chemical etching and atomic force microscopy. It was found that the insertion of multiple GaN quantum-dot layers into the buffer layer effectively reduced the dislocation density in the epitaxial layers. As compared to a dislocation density of about 1010/cm2 in typical GaN films grown onto an AlN buffer layer, a density of about 3 x 107/cm2 was detected in GaN films grown with quantum dot layers.

Defect Reduction with Quantum Dots in GaN Grown on Sapphire Substrates by Molecular Beam Epitaxy. D.Huang, M.A.Reshchikov, F.Yun, T.King, A.A.Baski, H.Morkoç: Applied Physics Letters, 2002, 80[2], 216-8