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DS: Dünne Schichten

DS 23: Postersitzung I

DS 23.4: Poster

Freitag, 4. März 2005, 16:00–18:30, Poster TU B

Metallic nanowires and nanoparticles on facetted alumina templates — •C. Herweg¹, S. Sievers², M. Albrecht², U. Siegner², and H. C. Freyhardt¹ — ¹Institut für Materialphysik, Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen — ²Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig

Highly ordered facetted surfaces can be obtained by annealing of α −Al₂O₃  (10 10), (m−plane)   at ∼ 2/3 · T_m    (T_m : melting temperature) in air. Transmissionelectronmicroscopy (TEM) reveals a periodicity of ∼300nm and a hight of ∼50nm . The facets are found to be almost symmetric, comprising an angle of 17,6^∘ with the original (10 10) surface. The surface morphology of the facets differs, crystallographically flat on one facet, nanofacted on the other one. These facetted substrates were used for the preparation of metallic nanowires by deposition of iron, cobalt and gold under shallow incidence with magnetron sputtering. The shadowing effect permits the preparation of well-defined, separated wires with a width of ∼100−150nm as will be shown by means of atomic force microscopy (AFM), magnetic force microscopy (MFM) and scanning electron microscopy (SEM). The nanowire length is determined by the undisturbed length of the underlying facet (∼150µ m ). A spheroidization instability of these wires upon annealing results in a pearl chain like ordered array of metal clusters. Magnetic characterisation by MOKE and SQUID confirm the morphological change from wires to separated particles. MFM shows that the particles can be remanently magnetized with external fields of different orientations.