Nanostructures and nanostructured systems from clusters preformed

in the gas phase ^(*)

A. Perez, P. Mélinon, V. Dupuis, B. Prével, J. Tuaillon, L. Bardotti, P. Masenelli,

F. Tournus, and L. Favre

Laboratoire de Physique de la Matière Condensée et Nanostructures

Université Claude Bernard Lyon 1 - 69622 Villeurbanne, France.

The Low Energy Cluster Beam Deposition technique (LECBD) has been developed to produce original cluster assembled nanostructures. This technique consists of depositing the very low energy neutral clusters produced in an inert gas condensation source. In the typical cluster-size range (from a few tens up to a few thousands of atoms) considered in these experiments, clusters are not fragmented upon impact on the substrate leading to a characteristic film growth process. Nanostructures of any kind of materials (covalent, metallic) are prepared by this technique, and both the characteristic nanostructured morphology and the memory effect of the original free cluster structures are at the origin of their properties.

After a brief review of techniques to produce, analyse, and deposit clusters, some specific aspects of the nucleation and growth process which governs the cluster-assembled nanostructure formation will be presented. Some characteristic examples of functionalized cluster-assembled materials prepared by LECBD will be also described : Semiconducting nanostructures from silicon and mixed silicon-carbon cage like clusters (fullerenes and heterofullerenes), and magnetic nanostructures from transition metal (i.e. Co) and mixed transition metal-rare earth clusters (i.e. Co-Sm). Finally, recent results on the preparation of 2D-organized arrays of cluster-assembled nanostructures for applications to high integration-density devices (Tbits/in²) will be reported.

(*) Recent review articles and books on the subject :

-"Nanostructured materials from clusters : synthesis and properties".

A. Perez et al, Materials Transactions, Special Issue on Nano-metals 1, Vol 42, N°8, pp 1460-1470 (2001).

-"Nanoclusters deposited on surfaces"

C. Binns, Surf. Sci. Rep., 44(1-2), pp 1-49 (2001).

-"Cluster beam synthesis of nano-structured materials"

Eds. P. Milani and S. Iannota, Springer Verlag, Berlin (1999).