Multifunctional Cylindrical Nanoobjects: From ALD Growth towards Physical Model Systems

Date: 
Monday, April 16, 2012 -
4:00pm to 5:00pm
Speaker: 
Kornelius Nielsch
Speaker's Institution: 
Institute of Applied Physics, University of Hamburg, Germamy

A broad range of potential applications of magnetic nanostructures have been developed in the recent years. Magnetic data storage, microelectronics, or biomedical uses such as cell separation or biosensing present a special interest among these applications. Atomic layer deposition (ALD) is a very suitable method for the conformal deposition of magnetic thin films in pore structures of high aspect ratio, while offering the precise tuning of the layer thickness and high uniformity.

By ALD coating of self-ordered Al2O3 membranes, arrays of magnetic nanotubes with diameters down to 20 nm and wall thicknesses of less than 5 nm have been achieved. The magnetic properties of the nanotube arrays as a function of wall thickness and tube diameter have been studied by using SQUID magnetometry and compared with magnetic simulations. We will discuss the properties of magnetic multi-layered nanotubes (core-shell) and the application of conformal magnetic coatings of other template systems and 3D nanostructures.

 

Furthermore, thermoelectric materials might play an increasing role for the efficient use of energy resources and waste heat recovery in the future. We have grown nanowires of V-VI semiconductors by cyclic vapour liquid solid growth mode. The synthesized Sb2Se3 and Sb2S3 nanowires have been applied successfully as three dimensional substrates for epitaxial atomic layer deposition at low temperatures starting at 90 °C. The presentation will be completed by the presentation of selected results on the thermoelectric characterisation of individual semiconductor nanowires and the outlook of ALD of thermoelectric films. 

 

References:

M. Knez, A. Kadri, C. Wege, U. Gösele, H. Jeske, and K. Nielsch, "Atomic Layer Deposition on Biological Macromolecules: Metal Oxide Coating of Tobacco Mosaic Virus and Ferritin", Nano Letters 6, 1172 (2006).

R. B. Yang, N. Zakharov, O. Moutanabbir, K. Scheerschmidt, L. M. Wu, U. Gösele, J. Bachmann, K. Nielsch, "The Transition between Conformal Atomic Layer Epitaxy and Nanowire Growth", J. Am. Chem. Soc. 132, 7592 (2010).