The nature of Co/(100)Si interfaces which had been formed at room temperature was studied by using X-ray absorption fine-structure, low-energy electron diffraction, and Auger electron spectroscopic methods. The evaporation of Co onto chemically etched and annealed (100)Si 2 x 1 surfaces led to a coverage of about half of a monolayer for the adsorption of Co at the 4-fold hollow sites of the locally non-reconstructed (100)Si surface. At higher coverages, the Co atoms occupied interstitial and substitutional sites of the Si lattice. Annealing (550 to 650C, 300s) caused the diffusion of Co into the Si lattice, where the Co atoms occupied only adamanthane sites. After the evaporation of Co onto sputter-annealed 2 x 1 (100)Si surfaces, only the formation of a locally ordered CoSi2-like phase was observed at coverages of between 0.8 and 14 monolayers.

H.L.Meyerheim, U.Döbler, A.Puschmann: Physical Review B, 1991, 44[11], 5738-44