title: Spatial variation of au coverage as the driving force for nanoscopic pattern formation.
abstract: Au induced faceting of a 4 degrees vicinal Si(001) surface was studied with chemical resolution using soft x-ray photoemission electron microscopy. For the first time a direct and quantitative determination of the local Au coverage in situ and during deposition was possible. Au atoms, necessary for the expansion of (001) terraces, are accummulated from a lattice gas, resulting in a phase separation between Au enriched terraces and Au depleted step bunches. During a second stage Au also adsorbs on the step bunches and transforms them into (119) facets. A simple Monte Carlo simulation shows that the initial coverage difference between terraces and bunches determines the regularity of the formed mesoscopic grating.
authors.affiliation: Institut für Festkörperphysik, Universität Hannover, Appelstrasse 2, 30167 Hannover, Germany.
authors.forename: F J
authors.initials: FJ
authors.lastname: Meyer zu Heringdorf
authors.forename: T
authors.initials: T
authors.lastname: Schmidt
authors.forename: S
authors.initials: S
authors.lastname: Heun
authors.forename: R
authors.initials: R
authors.lastname: Hild
authors.forename: P
authors.initials: P
authors.lastname: Zahl
authors.forename: B
authors.initials: B
authors.lastname: Ressel
authors.forename: E
authors.initials: E
authors.lastname: Bauer
authors.forename: M
authors.initials: M
authors.lastname: Horn-von Hoegen