Anisotropic roughness in Ge/Si superlattices

We discuss measurements of buried interfaces utilizing x-ray specular reflectivity profiles, and high-resolution x-ray reflectivity measurement of diffuse scattering. Interface structure is compared to atomic force microscopy characterization of the morphology of the Si cap layer overlying the buried structures. The results show that the morphology of roughness on the growth surface is greatly influenced by substrate miscut, and tends to form one-dimensional undulations. Roughness along the miscut direction is highly replicated from interface to interface, but roughness perpendicular to the miscut evolves more rapidly during the growth process. This effect is characterized by a reduced vertical correlation length in x-ray diffuse scattering in one azimuthal orientation.NRC publication: Ye