Projet ANR-07-BLAN-0270 – ThinQ : Quantum size effects in thin films on complex metallic alloys
Programme : Blanc (BLANC) 2007
Année de financement : 2007
Coordinateur du projet : CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE - DELEGATION REGIONALE CENTRE-EST (CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE - DELEGATION REGIONALE CENTRE-EST)
Partenaires : Centre national de la recherche scientifique
Montant : 300000.0 euros
Date de début : 2007
Durée : 36 mois
Résumé : This project focuses on the understanding and the tailoring of the structure  property relationship at surfaces of complex metallic alloys. In the last few years, we have contributed significantly to crystallographic and electronic surface structure determination of some typical quasicrystalline phases. This was a necessary step for further studies of surface properties and thin film growth at a fundamental level. We have made significant progress in the study of thin film growth on complex surfaces, which is a topic of ongoing excitement, partly due to the prospect of discovering unusual properties in pseudomorphic films, and partly due to the possibility of using quasicrystals as templates for building nanostructures. -  -  We have now succeeded in growing artificial quasiperiodic systems by deposition on quasicrystalline templates. We also have discovered that two different phenomena uniquely combine on quasicrystalline substrates: quantum size effects (QSEs) and trapping effects. -  The trapping effect is a consequence of an ordered array of specific sites of the substrates which present a strong adsorption energy and act as nucleation centre during thin film growth. This is of interest for a larger research community, where significant work is being done on heteroepitaxial systems, with the idea of fabricating nanostructures on solid surfaces for technological applications. In general, exploitation of natural growth morphology is considered as an alternative to optical lithography to obtain self-organized patterns of nanosized features, such as quantum dots in semiconductor heteroepitaxy. -  Quantum size effects relate to the appearance of discrete electronic states arising from the confinement of the electron within the film thickness. QSE is expected to modulate greatly the electronic structure near the Fermi level with the film thickness, and consequently its physical and chemical properties. Therefore controlling the film thickness offers the possibility to engineer the electronic structure. On quasicrystalline substrate, QSE are manifest at room temperature and even above. -  -  The main goal of this project is to control the growth and to investigate the properties of thin films stabilized by QSE on quasicrystalline surfaces. We will specifically focus on the relation between the electronic confinement in the film and the physical properties like adhesion and chemical reactivity of these films. The convergence of QSE and trapping effects opens the possibility of forming ordered quasiperiodic array of nanoislands stabilized by quantum size effects. We will explore this possibility and investigate the physical properties of such nanostructured thin films. Finally, we will expand our studies to related periodic complex metallic alloys. To achieve this goal, we propose the following plan with five workpackages: -  -  WP 1: Mechanisms and kinetics associated with the formation of thin films stabilized by QSE. -  WP 2: Surface preparation and adsorption site determination of new complex metallic alloys. -  WP 3: Electronic structure characterization of thin films. Origin of the QSE. -  WP 4: Ordered array of nanodots stabilized by QSE. -  WP 5: Physical and Chemical Properties. -                                                                                                                                                                                                                                                                                                                                                                                                     ...