ATOMIC-STRUCTURE OF SILVER CLUSTERS ON SILICON

The atomic structure of silver clusters formed on a Si(111)-7 x 7 sing le crystal surface by annealing a silver thin film condensed at room t emperature is investigated by the diffraction of medium-energy quasiel astically scattered electrons. Simulation of the diffraction pattern o btained within a nearly complete electron reflection hemisphere shows that the silver islands formed on the silicon have an ordered structur e and a fixed orientation relative to the substrate. Close-packed Ag(l ll) monolayers, which form a face-centered cubic structure, are arrang ed parallel to the surface, the [(1) over bar (1) over bar 2] directio n of these microcrystals being antiparallel to the [ (1) over bar (1) over bar 2] axis of the substrate. (C) 1997 American Institute of Phys ics.