The early stages of Fe/Si(111) interface formation have been investigated using x-ray photoelectron diffraction. Deposition of Fe in the range of one monolayer on Si(111)7×7 at room temperature results in the destruction of the 7×7 reconstruction. After a slight anneal, a well ordered interface is formed. This reacted layer is terminated by a top Si bilayer, which is rotated 180° with respect to the substrate stacking sequence. Fe atoms occupy substitutional Si lattice sites in the next bilayer underneath, keeping an interface coordination similar to the eightfold type. Thus, this initial interface already exhibits several of the most important features of thicker epitaxial silicide films. This result is evidence of the importance of the earliest stages of epitaxial growth to understand the properties of thicker layers.

• Received 24 October 1996

DOI:https://doi.org/10.1103/PhysRevB.55.R7315