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Metallic nanostructures
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Device miniaturization is a key issue of the modern solid state physics research and technology development. However, the laws of quantum mechanics and the limitations of fabrication techniques soon may prevent further reduction in the size of today’s conventional diode, transistor, FET and MOSFET. This has led to the birth of the “Nanotechnology” that is one of the most active and exciting research fields in material science. It takes advantage of quantum phenomena that emerge on the nanometer scale: electron confinement and discreteness effects, transport of single electrons, size effects, etc. The fabrication and the atomic level manipulation of self-organized nanostructured materials by metallic nanoclusters offer the possibility to design innovative functional nanodevices with improved thermodynamic, electronic, optical, logic, storage performances. The first requirement for the technological application of self-assembled metallic nanoclusters is the capability to control their structural properties (size distribution, distance, surface and volume density, shape, etc.). So, the first step towards the applications of metallic nanoclusters based materials is the development of methodologies (for example based on annealing processes, ion beam or electron beam processes, and so on) to tune their structural characteristics and the correlation of such features with the process parameters (i. e. annealing time and temperature, ion and electron beam energy and fluence, and so on) by opportune theoretical models. The following step requires the correlation of the physical and chemical properties of such materials with the structural ones (often within the framework of mesoscopic theory) in view of their engineering in technological devices. For example, the well established electronic properties of microelectronic devices (e.g., Schottky diodes) change drastically when their characteristics sizes are reduced to the nanometer scale and became strongly size-dependent. On the other hand, the nanoscale level analyses of structural, physical and chemical properties of such materials requires the crossing use and improvement of several advanced microscopic techniques such as atomic force microscopy, transmission electron microscopy, scanning electron microscopy, Rutherford backscattering spectrometry, etc. |
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RECENT HIGHLIGHTS by MATIS: |
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| The thermal induced kinetic growth mechanism of Au nanoclusters on hexagonal SiC and SiO2 surfaces was quantitatively studied by crossing microscopic technique analyses such as atomic force microscopy, scanning electron microscopy and transmission electron microscopy. On both types of substrates, clustering is shown to be a ripening process of three dimensional structures controlled by surface diffusion and the application of the ripening theory allowed us to derive the surface diffusion coefficient and all other parameters necessary to describe the entire process. The systems Au nanoclusters/SiC and Au nanoclusters/SiO2 are proposed as nanostructured materials for nanoelectronic and nanotechnology applications. Ruffino F., Canino A., Grimaldi M. G., Giannazzo F., Bongiorno C., Roccaforte F., Raineri V. Self-organization of gold nanoclusters on hexagonal SiC and SiO2 surfaces J. Appl. Phys. 101, 064306 (2007) - DOI: 10.1063/1.2711151 |
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| By conductive atomic force microscopy measurements we probed the electrical properties of nano-Schottky diodes fabricated by Au nanoclusters on SiC substrate. The main result concerns the Schottky barrier height (SBH) dependence on the nanocluster size (2R): it increases when the nanocluster size increases and tends asimptotically to the Schottky barrier height of the macroscopic Au/SiC contact. We interpreted such a behaviour considering the physics of few electron quantum dots merged with the concepts of ballistic transport and thermoionic emission. |  |
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Ruffino F., Grimaldi M. G., Giannazzo F., Roccaforte F., Raineri V. Size-dependent Schottky barrier height in self-assembled gold nanoparticles Appl. Phys. Lett. 89, 243113-1 (2006) - DOI: 10.1063/1.2405407 |
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PARTICIPANTS |
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| GRIMALDI Maria Grazia | 095 3785352 | |
| RUFFINO Francesco | 095 3785289 | |