Chemisorption of a Ag atom on a Si(100) 2x1 surface: Local surface deformation

In the initial step of the Si(100) surface metallization, it is shown that chemisorption of a Ag atom in a cave site is due to the Si(100) surface local deformation to match the small Si-Ag bond length. With a frozen Si(100)2x1 surface, Ag is not adsorbed in a cave site but laterally, bonded to a single surface Si. The STM image calculated with Ag in a cave site is ovoidal, extending over the two bonded Si. This shows that the appearance of Ag in an STM image is due to the local electronic structure of the Si-Ag-Si bonds and not to the vibrations of Ag parallel to the surface. (C) 1997 Elsevier Science B.V.