Dresden 2006 – wissenschaftliches Programm
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DS: Dünne Schichten
DS 24: Poster presentation
DS 24.17: Poster
Dienstag, 28. März 2006, 15:00–17:30, P2
Growth and electronic structure of ultrathin KCl layers on Cu(111) — •Robin Ohmann1, Michael Vogelgesang1, Oguzhan Gürlü1, Lars Diekhöner2, M. Alexander Schneider1, and Klaus Kern1 — 1Max-Planck-Institut, Nanoscale Science Department, Stuttgart, Germany — 2Aalborg Universitet, Institut for Fysik og Nanoteknologi, Aalborg, Denmark
Thin films of insulating materials on conducting surfaces are of great interest as decoupling layers for adsorbates. In the single to few monolayer regime these films can still be investigated by Scanning Tunneling Microscopy and Spectroscopy (STM/STS). Ideally the insulating layer should not provide any electronic structure within its electronic gap. This was checked for the case of ultrathin KCl layers grown in UHV on Cu(111) by low-temperature STM/STS measurements. The Cu(111) surface state is shown to evolve into an interface state with an almost identical dispersion relation in contrast to findings in the NaCl/Cu(111) system (1). Therefore the electronic changes introduced by the KCl are found to be minimal; the layer behaves like an additional tunneling barrier. KCl covered Cu is yet still clearly distinguishable from the Cu(111) surface by measuring the image-potential states. At voltages of 2.7V we identify the onset of a conduction band derived state of the KCl layer. This state is followed by the Stark-shifted series of image-potential states. A detailed discussion of the observed STS spectra at high positive sample bias will be presented.
[1] J. Repp, G. Meyer, K. H. Rieder, PRL 92, 036803 (2004)