Initial stages of Ba adsorption on the Si(100)-(2x1) surface at room temperature

Scanning tunneling microscopy has been used to study the initial stages of room-temperature adsorption of Ba atoms on a clean Si(100)-(2 X 1) surface. It is found that most Ba atoms an located at type C defects, which stabili zes the dimer buckling in their vicinity, while the rest are located at sin gle dimer sites on top of the Si dimer rows. Analysis of the images reveals that the Ba-Si(100) interactions are mediated by a partial charge transfer from the adsorbate to the substrate. [S0163-1829(99)03207-5].