The effect of GaN and InxGa1-xN interlayers on the strain state and defect density of GaN buffer layers was studied. The layers were grown by low-pressure MOVCD onto c-plane sapphire substrates and were investigated by means of in situ reflectometry, atomic force microscopy, photoluminescence and high-resolution X-ray diffraction. Etch-pit densities were determined by wet chemical etching in hot phosphoric acid. It was found that InxGa1-xN interlayers slightly decreased the defect density and reduced the strain in the GaN buffer layers.

Influence of Low-Temperature Interlayers on Strain and Defect Density of Epitaxial GaN Layers. U.Rossow, F.Hitzel, N.Riedel, S.Lahmann, J.Bläsing, A.Krost, G.Ade, P.Hinze, A.Hangleiter: Journal of Crystal Growth, 2003, 248, 528-32