Functional nanostructures from clusters
Résumé
Functional cluster-assembled nanostructures with original structures and properties are prepared using the Low Energy Cluster Beam Deposition method (LECBD). This technique consists in depositing supersonic clusters produced in the gas phase using a combined laser vapourisation-inert gas condensation source. Low energy clusters with typical sizes ranging from similar to 1 to a few nm are not fragmented upon impact oil the substrate (soft landing regime) leading to the formation of cluster-assembled nanostructures which retain the original structures and properties of the incident free Clusters. Model nanostructured systems of any kind of materials (metallic, covalent, oxides) well suited for fundamental Studies in various fields (nanoelectronics, nanomagnetism, nanophotonics, catalysis or nanobiology) and for applications to very high integration-density devices (similar to Tbits/in(2)) are prepared using this method. After a brief review of techniques to produce, analyse, mass select, and deposit Clusters in the LECBD-regime, the specific aspects of the nucleation and growth process which govern the formation Of cluster-assembled nanostructures oil the substrate are presented, especially the preparation of 2D-organised arrays Of cluster-assembled dots by depositing low energy Clusters on FIB-functionalised Substrates. Characteristic examples Of Cluster systems prepared by LECBD are also described: i metallic (Au. Ag, Au-Ag, Au-Ni, Ag-Pt)) and oxide (Gd2O3, ZnO) cluster-assembled nanostructures for applications to linear and non linear nano-optics ii magnetic nanostructures from Co-based nanoclusters (i.e., Co-Pt) exhibiting a high magnetic anisotropy which is Well Suited for applications to high density data storage devices iii gold or Pd-Pt or Au-Ti clusters for chemical reactivity and catalysis applications. In some specific cases, we were able to perform Studies from all isolated individual nanocluster LIP to 2D or 3D-collections of non-interacting or interacting particles leading to a rather good understanding of the intrinsic as well as the collective properties at nanoscale.