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WPA. Fundamental phenomena in surfaces, interfaces and thin films

In relation with the general objective of FUNCOAT, i.e., the optimization of procedures for the modification/functionalisation of surfaces, it is indispensable to reach a deep knowledge of the underlying physical phenomena. Thus, although some functionalisation processes are already available, even at industrial scale, the development of new functionalities requires detailed knowledge in fundamental aspects, related to the mechanisms of thin film growth, the interaction processes of the growing material with external species and/or radiation, including the understanding of interface phenomena, description of phase mixing effects, etc.

WP.A has been structured in several activities encompassing experiments with ideal systems and theoretical descriptions, all of them with the aim of getting a description of the fundamental processes occurring during the functionalisation of surfaces and/or growth of thin films.

A1.
Plasma modelling and plasma interaction with surfaces: Many surface activation procedures and thin film techniques are based on the use of plasmas. Therefore, the understanding of the plasma physics and chemistry is essential to predict the properties of functionalized surfaces. In this activity the identification of plasma species and the determination of parameters such as the electron energy, sheath effects, excited species, chemical changes at surfaces, etc will provide the required information to model the plasmas and to predict the effect of the interaction of these plasmas with the surfaces, and confront them with the experimental results stemming from the surface characterisation of model systems of modified materials..
A2.
Modelling of thin film growth without external excitation:
Thin film growth mechanisms under the sole effect of temperature are addressed in this activity. It will start with thermodynamic and finite element modelling to optimize the deposition parameters and surface layer properties. The results should provide the basis to determine coating compositions intended for given applications prior to their synthesis by different methods contemplated in FUNCOAT. In parallel, the application of Montecarlo and Molecular Dynamic principles to the theoretical description of the growth mechanism of thin films will be also carried out. Dynamic scaling approaches will be applied to correlate surface roughness evolution with growing mechanisms.
A3.
Modelling of thin film growth and surface modification with external excitation: In most methods of thin film growth and surface functionalisation, the substrate and/or the growing film surface are activated with a bunch of techniques, including ion and electron beams, photons (i.e., laser or UV radiation), etc. This external activation induces chemical changes and contributes to the development of new surface micro- and nanostructures. In this activity, a description and modelling of the corresponding functionalisation procedures will be tried by using similar methodologies than in A2, but considering the effect of an external activation.
A4.
Size effects in magnetic and electronic structure: This activity deals with the influence of the size/shape effects of their local domains in the macroscopic properties of functionalised and nanostructured surfaces.
Here, the fundamental description of basic questions, related with the electronic structure and/or magnetic order of the surface nanostructures, will be considered. From the fundamental studies carried out in this activity, it is expected to gain valuable information required for the development of magnetic devices in WP.F and at the same time to get a deeper understanding of the basic electrical properties of surfaces and thin films, as contemplated in WP.E. As an additional output of activity A4, it is expected to produce basic models able to predict the dependence of the electronic and magnetic properties of functionalised surfaces on their nanostructure.
A5.
Advanced characterization of the micro- and nano-structure:
Specific surface and in-depth methodologies of structural and chemical analysis such as photoelectron spectroscopies, Micro-Raman, AFM, etc. will be systematically used through all FUNCOAT activities. These techniques provides valuable information about the chemical and microscopic structure of materials, like bonding orientation, state of disorder, residual stresses, appearance of new crystallographic phases, etc. Real breakthroughs in the use of some of the most advanced microscopy techniques (TEM and HRTEM and associated techniques, EFTEM, X-EDS, EELS) are also expected by the development of new methodologies of analysis of functionalised surfaces and thin films.

The internal relationship between the activities/tasks with themselves and with other Work Packages is described in the following picture.

Diagrama WPA