Dresden 2003 – wissenschaftliches Programm

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SYMN: Metallic nanowires

SYMN 1: Metallic nanowires I

SYMN 1.1: Hauptvortrag

Freitag, 28. März 2003, 09:30–10:00, HSZ/01

Self-organized structures on flat crystals: Nanowire Networks formed by metal evaporation — •Rainer Adelung — Technische Fakultät der CAU Kiel, Lehrstuhl für Materialverbunde, Kaiserstr. 2 , D-24143 Kiel, Germany

An easy way to cover large areas with nano- or microstructures is self-organization. A frequently used method to obtain self-organized nanostructures is to use a pre-structured surface. Typical examples of pre-structured surfaces are reconstructed or vicinal surfaces (e.g., stepped silicon [1]). Surfaces of layered transition metal dichalcogenide (TMDC) crystals have no reconstruction and have almost no step edges or other defects. Against intuition, these flat crystals are well suitable for self organized structuring on the nano- and micrometer scale. Metal evaporation leads not only to a simple cluster formation, but also, depending on the preparation conditions, to nanowires, down to 8 nm thin, covering in a network with mesh diameters of 200-400 nm crystals on the millimeter scale [2]. Moreover, other structures like cluster arrays in the form of triangles or parallelograms can be found as well as large tunnel network structures. The nanowires and other structures occur because, on the one hand, long diffusion length enable a long range organization. On the other hand, the weak substrate adsorbate interaction enables more complex phenomena to determine the structuring. In contrast to simple diffusion rules like “if position is reached, then stay” which will be found on surfaces with pronounced adsorption energy differences, here more complex "second order" phenomena such as strain, charge transfer and differences in diffusion speed dictate the structures. Besides the details of the formation mechanisms, the influence of preparation conditions and the physical properties of the nanowire networks and the other structures will be discussed.

[1] J. Viernow, J.-L. Lin, D. Y. Petrovykh, F. M. Leibsle, F. K. Men, and F. J. Himpsel, Appl. Phys. Lett. 72, 948 (1998). [2] R. Adelung, F. Ernst, A. Scott, M. Tabib-Azar, L. Kipp, M. Skibowski, S. Hollensteiner, E. Spiecker, W. Jäger, S. Gunst, A. Klein, W. Jägermann, V. Zaporojtchenko and F. Faupel, Adv. Mater. 15, 1056, (2002).