Photoemission studies of atomic redistribution at gold–silicon and aluminum–silicon interfaces

We have used soft x-ray photoemission spectroscopy (SXPS) to monitor the rearrangement of Si and metal atoms during the initial stages of Au or Al interface formation with UHV-cleaved (111) or (100) Si surfaces. From Si 2p core level spectra as a function of metal overlayer thickness and as a function of incident photon energy, we obtain evidence for strong Si bond changes at submonolayer Au coverages but only weak Al–Si interactions. Marker experiments reveal that Au diffuses into Si (Si diffuses into Al) with the first few deposited metal overlayers. We examine our new information on the interface evolution at room and elevated temperatures in relation to the corresponding bulk phase diagrams.