Structural aspects of the reaction of Ni with Si{111} surfaces

Abstract

LEED (low-energy electron diffraction) intensity studies confirm the formation of epitaxial NiSi 2 on Si{111} with two different rotational orientations (A- and B-type) depending on the initial amount of Ni. The existence of a well-crystallized Si{111}√3×√3−30°−Ni structure at a surface coverage of 1 3 − 2 3 monolayer is established. The LEED intensities from this structure are found to change after different preparations. These variations can be explained by the existence of at least two equivalent adsorption sites for Ni in each √3 unit mesh, and the coexistence of two rotational domains of the √3 structure at 60° from one another.