High-resolution photoemission spectroscopy study of clean and Au-nanowire-decorated Si(5512) surfaces

We have examined the Si 2p photoemission line shape of the clean Si(5 5 12)2x1 surface in detail and have investigated the evolution of the Au-induced nanowires on this surface at different temperatures with low-energy-electron diffraction and photoemission spectroscopy. The Si 2p spectra from the clean 2x1 surface exhibit very complex line shapes composed at least of five different surface-related components. Possible origins of the most distinct surface component with a surface core-level shift of -0.62 eV are discussed within the three different structure models proposed so far. Upon Au deposition, the intensity of that particular surface component was largely reduced indicating that the Au adsorbates interact dominantly with the specific Si surface atoms related. With an annealing above 500degreesC after Au deposition of 0.2 ML, the surface drastically changes into a metallic phase, as shown clearly in the valence band photoemission spectra, along with the gradual formation of the (337)x2 facets observed in LEED. In this transition, a new Au 4f component appears while the Si 2p core-level spectra keep alike. This indicates that the surface metallization involves the rearrangement of Au adsorbates, possibly the formation of new Au chains on the surface.