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O: Fachverband Oberflächenphysik

O 35: Poster Session I (Metal, semiconductor and oxide substrates: structure and adsorbates; Graphene)

O 35.63: Poster

Dienstag, 12. März 2013, 18:15–21:45, Poster B1

Epitaxial growth of NaCl on thin KCl(100) films on Ag(100) studied by SPA-LEED — •Christian Marquardt, Alexander Paulheim, and Moritz Sokolowski — Institute for Physical and Theoretical Chemistry, University of Bonn, Wegelerstraße 12, 53115 Bonn, Germany

Heteroepitaxy of insulators and ionic materials is of basic interest for understanding the interactions at the respective interfaces. So far the heteroepitaxy of alkalihalides has been studied by various groups using single crystals and RHEED [1,2]. In the present work, we studied the epitaxy of NaCl on KCl by SPA-LEED. In order to avoid charging effects in the electron diffraction, we used thin films of KCl(100) epitaxially grown on a Ag(100) surface. For different growth temperatures we observed two different growth modes: At 300 K, we get highly disordered, but closed layers of NaCl. We observe a coherent transition between the lattices of KCl and NaCl and a relaxation of the NaCl lattice constant after few monolayers. At 500 K, we observe the formation of ordered NaCl islands with uncovered areas of the KCl and Ag surfaces in between. The quality of the NaCl films can also be characterized by optical spectra of isolated PTCDA molecules deposited on these. On NaCl structures grown at 500 K, the spectra are broadened, which we explain by a large diversity of adsorption sites related to structural defects of the NaCl films. Supported by SFB 624.
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