Structural study of monolayers of Sb on Ge(111) with different surface reconstructions*

Abstract

X-ray standing waves (XSW) and low energy electron diffraction (LEED) have been applied to the structural study of a monolayer of Sb on cleaved Ge(111). Initial Ge(111) surfaces with 2×1, c(2×8), and 1×1 LEED reconstructions have been obtained by preannealing the 2×1 room temperature cleavage surfaces. Although in all three cases, the Sb deposition followed by a 600 °C anneal on these different initial reconstructions results in a 2×1 or 2×1/2×2 overlayer LEED geometry, the XSW data indicate large differences in the local Sb bonding structure between them. For the initial 2×1 surface, Sb forms Seiwatz chains. Preannealing of the surface causes a decrease in the Sb coherent fraction and an increase of the substrate overlayer distance which is inconsistent with a single site absorption geometry and indicates large disorder of the 1×1 surface prior to the Sb deposition.