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The structure of a δ-doped crystal, Si(800Å)/Ge(1ML)/Si(001), grown by molecular beam epitaxy has been studied by surface X-ray diffraction and X-ray standing-wave method. The positions of the Ge layer and the Si capping layer are determined with respect to the Si substrate. In the analysis, the roughnesses of the interface and the surface are considered. The distance between the bottommost capping layer and the topmost substrate layer is 2.068±0.002 in units of the interlayer spacing of Si(004), while the distance between the Ge layer and the topmost Si substrate layer is 1.058±0.001. The former value corresponds to an averaged structure where the macroscopic elastic theory is applicable to the evaluation of the strain and the latter value corresponds to a microscopic structure where the bulk bond length is conserved. Coexistence of the two kinds of structures is made possible by the interfacial roughness.

The surface structure of a Pd layer electrochemically deposited onto Au(111) from PdCl 2− 4 solution has been studied by surface X-ray diffraction. By combining the measurements of the specular and non-specular rod profiles, both in-plane and out-of-plane structures have been determined. On the Au(111) electrode surface, Pd occupies the cubic closest packing site and forms a pseudomorphic smooth monolayer. The formation of the stable Pd overlayer is explained by the lifting of the surface reconstruction of the Au substrate. The PdAu bond length at the Pd/Au(111) interface has been found to be 2.82 A, which is close to the sum of the atomic radii of Pd and Au in each bulk.