Regensburg 1998 – scientific programme

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O: Oberflächenphysik

O 31: Nanostrukturen

O 31.1: Talk

Thursday, March 26, 1998, 16:15–16:30, H36

Formation of laterally confined Cu clusters in nanometer sized holes on Au(111) with the help of in situ electrochemical STM — •X. H. Xia, R. Schuster, V. Kirchner, and G. Ertl — Fritz–Haber–Institut der Max–Planck Gesellschaft, Faradayweg 4–6, 14195 Berlin

We achieved to electrochemically grow laterally confined Cu clusters on Au(111) surfaces at nanometer scale with the help of in situ STM. Well ordered Cu crystallites were formed in nanometer sized holes which were electrochemically created by application of very short voltage pulses to the STM tip (–2.4 V vs. Cu²⁺/Cu height and 70 ns duration). Since the hole edges provide both, nucleation sites and effective binding sites, Cu deposition in these holes occurred already at 0 mV vs. Cu²⁺/Cu. The Cu deposition on the bare terraces is still hindered due to kinetic reasons, i.e., the formation of the nuclei. At higher overpotential (OP) the clusters in the holes grew rather epitaxially beyond the terrace. Their height depends on the applied OP, whereas their width is confined by the island edges. The dependence of the cluster height on the OP is explained in a simple model, where the excess electrochemical energy is consumed for the formation of the surface of the small clusters, i.e., the monoatomic steps at its circumference.