Berlin 2008 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 55: Poster Session III - MA 141/144 (Methods: Atomic and Electronic Structure; Particles and Clusters; Heterogeneous Catalysis; Semiconductor Substrates: Epitaxy and Growth+Adsorption+Clean Surfaces+Solid-Liquid Interfaces; Oxides and Insulators: Solid-Liquid Interfaces+Epitaxy and Growth; Phase Transitions; Metal Substrates: Adsorption of Inorganic Molecules+Epitaxy and Growth; Surface Chemical Reactions; Bimetallic Nanosystems: Tuning Physical and Chemical Properties; Oxides and insulators: Adsorption; Organic, polymeric, biomolecular films; etc.)

O 55.30: Poster

Mittwoch, 27. Februar 2008, 18:30–19:30, Poster F

Resistance of a single atom: scattering of electrons by single adatoms and small islands during homoepitaxial growth of Bi(111) films — •Hichem Hattab, Giriraj Jnawali, Boris Krenzer, and Michael Horn-von Hoegen — Fachbereich Physik, Universität Duisburg-Essen, Lotharstr. 1, 47048 Duisburg, Germany

Atomically smooth Bi(111) films on Si(001) were prepared following a recipe of G. Jnawali et al. (PRB 74 , 195340 (2006)) and were used as template to study the resistivity change during additional growth of Bi at 80 K by using a 4-probe technique and SPA-LEED. At very low Bi coverage of less than 0.01 bilayer (BL) a linear increase of the film resistivity was observed which suddenly changes to a square root dependence up to 0.5 BL. This behaviour is explained by a combination of Venables nucleation theory and Fuchs-Sondheimer behaviour. At very low coverage each deposited Bi adatom acts as single scatterer, which ultimately scatters the conduction electrons diffusively. The linear increase of the resistivity is proportional to the density of adatoms. With increasing Bi adatom density suddenly stable 2-dim. islands nucleate, the adatom density drops, and the islands grow in size at constant island density. Now the electrons are scattered at the step edges which density increase as square root of the coverage. At higher coverage the resistivity shows a bilayer oscillation indicating the oscillation in roughness which is followed by a 1/d behavior described by Fuchs-Sondheimer. From the slopes of the two initial regimes the effective cross-section for diffuse scattering of a single Bi adatom and of a bilayer step edge is calculated.