Diffuse X-ray scattering from epitaxial layers with screw dislocations perpendicular to the surface was calculated assuming correlated dislocation positions. The resulting intensity distribution was compared with a reciprocal-space map measured in a symmetric diffraction from a hexagonal GaN(0001) layer, and a good correspondence was achieved. From the fit, both the dislocation density and their correlation length were determined.

High-Resolution Diffuse X-Ray Scattering from Threading Dislocations in Heteroepitaxial Layers. S.Daniš, V.Holý, Z.Zhong, G.Bauer, O.Ambacher: Applied Physics Letters, 2004, 85[15], 3065-7