Surface and interface analysis of a low-dimensional Au-Si surface alloy on Au(110) by means of XPS and XPD.

The chemical and structural characteristics of a low-dimensional Au-Si surface alloy are presented in this work. Alloy formation was obtained by deposition of a sub-monolayer Si on Au(110). This preliminary phase to Si nano-ribbons is being investigated, as the transition from clean Au(110) to a silicon nano-ribbon coated surface is not yet understood. A multiple technique study has been carried out for detailed atomic structure determination and chemical investigation. Particular attention is paid to the clarification of the structural arrangement at the surface and at the interface. Using low-energy electron diffraction, the periodicity of the structure on long-range order could be examined. By means of high-precision photoemission measurements using synchrotron radiation, the electronic and atomic structure of the alloy can be presented. The investigation by photoelectron spectroscopy (XPS) using soft x-rays for a high surface sensitivity showed different chemical environments in the high-resolution spectra. The x-ray photoelectron diffraction (XPD) measurements, which are sensitive to the local atomic order, gave an approach to the structural configuration of the alloy. A new structural arrangement was found simulating both Au and Si XPD patterns. The results are compared to former proposed structure models. A deconvolution of the Si 2XPD pattern revealed the origin of two chemically shifted XPS components.