Analysis of grazing incidence X-ray diffuse scatter from Co-Cu multilayers

Grazing incidence diffuse X-ray scattering data from a Co-Cu multilayer with stepped interfaces grown by molecular beam epitaxy on a copper silicide buffer on a silicon substrate has been analysed using a computer code based on a fractal interface within the distorted wave Born approximation. We have extended the theory to include the scattering from a stepped interface and have shown that a single set of structural parameters can be used to obtain an excellent agreement between simulation and experimental data taken under very different X-ray optical conditions. The symmetry of the diffuse scatter on rotation about the surface normal can be explained if it arises from step bunching at the ends of extensive flat terraces. These steps have a self-affine nature, enabling the fractal model to be used successfully. (C) 1998 Elsevier Science B.V. All rights reserved.