Interface structure of MBE-grownCoSi2/Si/CoSi2layers on Si(111): Partially correlated roughness and diffuse x-ray scattering

The detailed interface structure of a ${\mathrm{CoSi}}_2$/Si/${\mathrm{CoSi}}_2$/Si(111) layer system grown by molecular-beam epitaxy is investigated in this paper. Measurements of the diffuse scattering in the region of total external reflection were performed and analyzed within the distorted-wave Born approximation. The analysis of the specularly reflected and the diffusely scattered intensity leads to a consistent set of interface and layer parameters, which are compared with results of Rutherford backscattering/channeling, transmission electron microscopy, and scanning tunneling microscopy. Although the diffuse intensity is dominated by a very rough surface layer, the roughness distribution of the buried interfaces of the epitaxial layers was determined rather exactly. It was found that the roughnesses of the interfaces of all epitaxial layers are of the order of monolayer steps. Very good agreement between the measurements and the calculations is achieved, if conformal roughness of the adjacent interfaces of each ${\mathrm{CoSi}}_2$ layer is included. Furthermore, the interfaces of the sandwiched Si layer are partially correlated, which means that the step structure is partially transferred through all interfaces up to the surface of the upper ${\mathrm{CoSi}}_2$ layer. © 1996 The American Physical Society.