Adsorption of Au Atoms on Si (111)-(7 X 7) Studied by Using Scanning Tunneling Microscopy

다국어 초록 (Multilingual Abstract)

We have studied Au adsorption on Si (111)-(7 × 7) at very low coverage (<0.1 ML) by means
of scanning tunneling microscopy. In addition to some bright clusters, we observed highlighted
triangles, which were characterized by bright spots at Si adatom sites, at both faulted and unfaulted
half unit cells with predominance at faulted ones. At the faulted half unit cells, the spots at
corner adatom sites appeared brighter than those at center adatom sites; the opposite was true at
the unfaulted half unit cells. These highlighted triangles could be identified independent of bias
in filled-state images but only at biases higher than 1V in empty-state images. The number of
highlighted triangles depended on the Au adatom coverage and the substrate temperature. More
highlighted triangles were found with lower Au coverage and lower substrate temperature. Jumping
of a highlighted triangle from an unfaulted to a neighboring empty faulted half unit cell was observed,
demonstrating the same origin (i.e., a single adatom) of a highlighted triangle for both half unit
cells.

참고문헌 (Reference)

1 more than 1 ML, "With the low coverage and at the substrate temperatureused in our experiment the substrate is not disruptedand the Au atoms adsorb on the surface Au-inducedreconstruction occurs only at higher temperatures andwith higher Au coverage than those in our experiment Diffusion of Au atoms into the substrate or Au-Si intermixingwas also reported for much higher Au coverage"