A theory was developed which described X-ray diffuse scattering from misfit dislocations in epitaxial layers. This was used to explain the origin of diffuse X-ray scattering from SiGe layers with a linearly graded Ge content. The distribution of the diffusely scattered intensity in the reciprocal plane, as measured by triple-axis X-ray diffractometry, was compared with theoretical predictions and good agreement was found. It was demonstrated that the main part of the diffusely scattered intensity originated from random strains that were caused by misfit dislocations at the substrate/epilayer interface or in the relaxed part of the compositionally graded layers. The contribution of threading dislocation segments to the diffuse scattering was relatively small.

V.Holý, J.H.Li, G.Bauer, F.Schäffler, H.J.Herzog: Journal of Applied Physics, 1995, 78[8], 5013-21