LARGE-SCALE AB-INITIO STUDY OF THE BINDING AND DIFFUSION OF A GE ADATOM ON THE SI(100) SURFACE

We identify the binding sites for adsorption of a single Ge atom on th e Si(100) surface using ab initio total-energy calculations. The theor etical diffusion barriers are in excellent agreement with experimental estimates. Using a large supercell we resolve the controversy regardi ng the binding geometry and migration path for the adatom, and investi gate its influence on the buckling of Si dimers. We find that the adat om induces a buckling defect that is frequently observed using scannin g tunneling microscopy, indicating that the study of a single adatom m ay be experimentally accessible.