Interstitial chemisorption and interface formation of Pt on Si(111) observed by surface extended x-ray-absorption fine-structure and L2,3-edge x-ray-absorption resonance spectroscopies

The first structural description of the Pt/Si(111)7×7 interface formation at room temperature is derived from Pt L3-edge surface extended x-ray-absorption fine-structure spectroscopy and x-ray-absorption resonance spectroscopy. Pt chemisorbs in the top Si double-layer sixfold interstitial sites, introducing stress in the surface and subsurface. Above monolayer thicknesses Pt diffuses within the silicon substrate and, upon Pt enrichment of the intermixed phase, clusters with Pt2Si local coordination nucleate.