EFFECTS OF ADATOM CONCENTRATION ON AU/SI(111) AND SI/AU INTERFACE FORMATION

Effects of Au(Si) adatom concentration on Au/Si(Si/Au) interface formation were investigated by photoemission and partial-electron-yield spectroscopy using synchrotron radiation, as well as by Auger-electron spectroscopy. Both interfaces are found to be reactive. The process of Au/Si(111) interface formation can be divided into three stages: for very low Au coverages, theta < 2 angstrom, Au forms a rather unreacted adlayer; in the intermediate range, 2 < theta < 25 angstrom, a reacted layer with a stoichiometry close to Au3Si is found; the high-coverage region is governed by the formation of an unreacted metallic Au phase beneath an about one reacted monolayer. For Si/Au the formation of a reacted phase is observed from the first stage of Si deposition. A model for the formation of both interfaces in terms of Au spd/Si sp hybridization is presented.