The dislocation structure of hydride vapour-phase epitaxial thick GaN layers, grown on sapphire, was studied by analyzing the micro-distortion tensor components. Symmetrical reflections (including reflections from planes which formed a large angle with respect to the basal plane), and 2 scanning modes in 2 geometries (Bragg, Laue), were used to obtain the tensor components. The relationships between tensor components and major dislocation types were specified. Various types of dislocation distribution were identified in thick GaN films that were grown on sapphire, with and without undoped and Si-doped metal-organic chemical vapour-deposited templates.

Bragg and Laue X-Ray Diffraction Study of Dislocations in Thick Hydride Vapour Phase Epitaxy GaN Films. V.Ratnikov, R.Kyutt, T.Shubina, T.Paskova, E.Valcheva, B.Monemar: Journal of Applied Physics, 2000, 88[11], 6252-9