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O: Fachverband Oberflächenphysik

O 56: Metal substrates: Epitaxy, growth and adsorbates

O 56.1: Talk

Thursday, March 26, 2009, 15:00–15:15, SCH A316

The Cu(110) surface state anisotropy as a probe for the initial stages of homoepitaxial growth — •Michael Hohage, Lidong Sun, Alexander Dorninger, and Peter Zeppenfeld — Institut für Experimentalphysik, Johannes Kepler Universität Linz, A-4040 Linz, Austria

Reflectance Difference Spectroscopy (RDS) revealed that the Cu(110) surface state anisotropy is an extremely sensitive probe to study adsorption and growth. The high sensitivity originates from the quenching of surface state contribution to the optical anisotropy at 2.1 eV, due to surface state scattering at adsorbates or point defects. Here, we apply this phenomenon to the investigation of the homoepitaxial growth of Cu on Cu(110). The transition from a step-flow growth at high temperatures to a 3D-island growth and finally to a re-entrant layer-by-layer growth at low temperatures can be easily observed. In addition, we were able to study the morphological changes occurring upon annealing after depositing 0.04 ML Cu at 10 K, by monitoring the partial recovery of the surface state anisotropy. The recovery proceeds mainly in two steps: (i) the onset of the adatom diffusion and nucleation of tiny clusters (90 K to 120 K) and (ii) the onset of adatom detachment and ripening of the clusters (> 190 K). Detailed analysis of the data with the help of a kinetic-Monte-Carlo code allows simulating the experimental results quantitatively and permits to quantify the effective cross-section of small ad-clusters for depolarization of the surface state.