Regensburg 2010 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

O: Fachverband Oberflächenphysik

O 41: Poster Session I (Semiconductor Substrates: Epitaxy and growth; Semiconductor Substrates: Adsorbtion; Semiconductor Substrates: Solid-liquid interfaces; Semiconductor Substrates: Clean surfaces; Oxides and insulators: Epitaxy and growth; Oxides and insulators: Adsorption; Oxides and insulators: Clean surfaces; Organic, polymeric and biomolecular films - also with adsorbates; Organic electronics and photovoltaics, Surface chemical reactions; Heterogeneous catalysis; Phase transitions; Particles and clusters; Surface dynamics; Surface or interface magnetism; Electron and spin dynamics; Spin-Orbit Interaction at Surfaces; Electronic structure; Nanotribology; Solid/liquid interfaces; Graphene; Others)

O 41.20: Poster

Dienstag, 23. März 2010, 18:30–21:00, Poster B1

STM and STS measurements on thin cerium oxide films grown on Pt(111) — •Christian Breinlich, Enrico Barletta, Jan Markus Essen, and Klaus Wandelt — Institute for Physical and Theoretical Chemistry, Wegelerstr. 12, 53115 Bonn, Germany

Thin oxide films, grown on a metal support, are showing interesting electronic properties. Therefore they are of great interest for the use as insulating layers in electronic devices and as a support for model catalysts. Cerium oxide has a high dielectric constant, which makes it useful in the fabrication of small capacitor devices. In this study we employed STM and STS to investigate the structural and electronic properties of thin cerium oxide films grown on Pt(111). The preparation process was studied by AES, LEED and HREELS. In a first step a Pt-Ce/Pt(111) surface alloy was prepared by evaporating a thin cerium film at 300 K with subsequent annealing to 1000 K. Then this alloy was oxidised under different conditions. Large amounts of oxygen at 900 K are leading to completely oxidised CeO₂ films, whereas smaller amounts of oxygen at 700 K are yielding mixed oxide phases. The former shows a (1.34 × 1.34) superstructure in LEED and rough, two to three layers high islands in STM. The mixed oxide phase shows a (4 × 4) superstructure and consists of flat islands with sharp edges. By employing STS it was possible to measure the band gap of the oxide films, which strongly depends on film thickness and stoichiometry.