Dresden 2009 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 42: Poster Session II (Nanostructures at surfaces: arrays; Nanostructures at surfaces: Dots, particles, clusters; Nanostructures at surfaces: Other; Nanostructures at surfaces: Wires, tubes; Metal substrates: Adsorption of O and/or H; Metal substrates: Clean surfaces; Metal substrates: Adsorption of organic/bio moledules; Metal substrates: Solid-liquid interfaces; Metal substrates: Adsorption of inorganic molecules; Metal substrates: Epitaxy and growth; Heterogeneous catalysis; Surface chemical reactions; Ab-initio approaches to excitations in condensed matter; Organic, polymeric, biomolecular films– also with adsorbates; Particles and clusters)

O 42.27: Poster

Mittwoch, 25. März 2009, 17:45–20:30, P2

Electron beam stimulated thermal desorption of oxygen: a lithographic method — •Jan Rönspies, Tammo Block, and Herbert Pfnür — Leibniz Universität Hannover, Institut für Festkörperphysik, Appelstr. 2, 30167 Hannover, Germany

We explored the structural limits of unconventional electron beam lithography by directly writing with an electron beam into ultra-thin SiO₂ films. These bare silicon window structures are suitable for growing contigous metallic nanowires with thickness of a few monolayers. These uncovered structures with lateral dimensions down to 10nm were analyzed further by tunneling microscopy. The Auger excitation process (Knotek-Feibelman mechanism) necessary for electron-beam stimulated thermal desorption of oxygen (EBSTD) allows generation of ultra-small structures. The subsequent processing step combines thermal desorption of the remaining monoxide and simultanous etching promoted by thermally activated silicon atoms, which turns out to be a strongly anisotropic process close to step edges [1]. Applying this combination of processes to a regularly stepped Si(557) sample which consists of a periodic array of small (111) and (112) oriented mini-facets with an average periodicity of 5.7nm normal to the steps, line widths close to the resolution of the electron microscope of 5nm were obtained. Thus exploitation of the quantized nature of ultrasmall structures far above liquid He temperatures becomes feasible as well as contacting of single molecules.

[1] J.Appl.Phys. 103, 064303 (2008)