Regensburg 2007 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 44: Poster Session II (Semiconductors; Oxides and Insulators: Adsorption, Clean Surfaces, Epitaxy and Growth; Surface Chemical Reactions and Heterogeneous Catalysis; Surface or Interface Magnetism; Solid-Liquid Interfaces; Organic, Polymeric, Biomolecular Films; Particles and Clusters; Methods: Atomic and Electronic Structure; Time-resolved Spectroscopies)
O 44.62: Poster
Mittwoch, 28. März 2007, 17:00–19:30, Poster C
Surface morphology and surface stress of CaF2 films on Si(111) — •Markus Neubert, Peter Kury, Friedrich Klasing, and Michael Horn von Hoegen — University of Duisburg-Essen, Institut of Experimental Physics
Thin CaF2 films with low defect density could be grown epitaxially on Si(111) due to the small lattice mismatch between CaF2 and Si. Due to the large thermal expansion coefficient (αCaF2 ≈19·10−6 K−1) of CaF2 the lattice mismatch increases strongly with temperature (αSi ≈2.6·10−6 K−1). As a consequence the vertical lattice parameter of thin CaF2 films increases by tetragonal distortion due to the build-up of compressive stress. We have grown CaF2 films at temperatures between 600K and 1100K by Molecular Beam Epitaxy (MBE). The resulting surface stress was measured in-situ during deposition by Surface Stress Induced Optical Deflection (SSIOD). The film morphology was investigated by ex-situ non-contact AFM. The thickness of the films was independently calibrated by X-Ray Reflection (XRR) measurements.