NONSPECULAR X-RAY REFLECTION FROM ROUGH MULTILAYERS

X-ray reflection from periodical multilayers with randomly rough interfaces has been described within the distorted-wave Born approximation. The method is suitable for calculating both specular x-ray reflection and nonspecular (diffuse) scattering. In this paper, both in-plane and vertical correlations of the roughness profiles have been considered and it has been demonstrated that the vertical roughness correlation substantially affects the nonspecular scattering. The theory can explain resonant effects observed in the beam scattered nonspecularly from a periodical multilayer. The theoretical approach has been used for the study of interfacial roughness in a long-periodic AlAs/GaAs multilayer and good agreement has been achieved between the experimental results and the theory.