Composition and atomic structure of the Si(111)31×31-In surface

Surface composition (In coverage and top Si atom density) and plausible adsorption sites of In atoms have been determined for the Si(111)31×31-In surface phase using scanning tunneling microscopy. The usage of indirect heating for the In–Si(111) interface formation has been shown to be a crucial requirement for composition determination, since it allows one to avoid the undesirable effects associated with surface atom electromigration. On the basis of the data obtained, a model of the atomic arrangement of the surface has been proposed. The model incorporates 17 In atoms in the 31×31 unit cell residing above the reconstructed Si layer containing 28 atoms. According to the model, the Si(111)31×31-In surface is free of dangling bonds and Si atoms in this structure preserve their basic tetrahedral bonding geometry.