The strain-relaxation phenomena and the formation of a dislocation network in 2H-InN epilayers during molecular beam epitaxy were reported. Plastic and elastic strain relaxations were studied by reflection high-energy electron diffraction, transmission electron microscopy, and high resolution X-ray diffraction. Characterization of the surface properties was performed using atomic force microscopy and photoelectron spectroscopy. In the framework of the growth model the following stages of the strain relief were proposed: plastic relaxation of strain by the introduction of geometric misfit dislocations, elastic strain relief during island growth, formation of threading dislocations induced by the coalescence of the islands, and relaxation of elastic strain by the introduction of secondary misfit dislocations. The model emphasizes the determining role of the coalescence process in the formation of a dislocation network in hetero-epitaxially grown 2H-InN. Edge-type threading dislocations and dislocations of mixed character were found to be dominating defects in the wurtzite InN layers. It was shown that the threading dislocation density decreased exponentially during the film growth due to recombination and, hence, annihilation of dislocations, reaching ~109/cm2 for ~2200nm thick InN films.

Effect of Dislocations on Electrical and Electron Transport Properties of InN Thin Films. I. Strain Relief and Formation of a Dislocation Network. V.Lebedev, V.Cimalla, J.Pezoldt, M.Himmerlich, S.Krischok, J.A.Schaefer, O.Ambacher, F.M.Morales, J.G.Lozano, D.González: Journal of Applied Physics, 2006, 100[9], 094902 (13pp)