High-resolution X-ray reciprocal space mapping in non-coplanar grazing-incidence geometry was used to determine the density of edge threading dislocations in c-oriented GaN epitaxial layers and the measured intensity distributions were compared with the results of numerical Monte Carlo simulations of diffuse scattering. It was demonstrated that a combination of diffraction data taken in coplanar symmetric and non-coplanar grazing-incidence geometries made it possible to obtain the densities of screw and edge threading dislocations.

Grazing-Incidence X-Ray Diffraction from GaN Epitaxial Layers with Threading Dislocations. M.Barchuk, V.Holý, B.Miljević, B.Krause, T.Baumbach: Applied Physics Letters, 2011, 98[2], 021912