A new multi-step metal-organic chemical vapour deposition method was used to suppress threading dislocations in GaN epilayers on c-plane sapphire. Nucleation island densities as low as 2.5 x 107/cm2 were reported. Subsequent overgrowth prevented the formation of new islands and stimulated the inclination of threading dislocations within nucleation islands before their coalescence. Epilayers with a threading dislocation density of 5.0 x

107/cm2 were grown. Nucleation island morphology and threading dislocation density were analyzed by atomic force microscopy. Transmission electron microscopy was used to support the results for the threading dislocation density and to evaluate the epitaxial relationship of the GaN films.

Multistep Method for Threading Dislocation Density Reduction in MOCVD Grown GaN Epilayers. T.Lang, M.A.Odnoblyudov, V.E.Bougrov, A.E.Romanov, S.Suihkonen, M.Sopanen, H.Lipsanen: Physica Status Solidi A, 2006, 203[10], R76-8