Browsing by Author "Noiseau, Guillaume Jack Nicolas"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Film deposition and mechanical properties of silver produced by impaction of nanoparticles(2012-12) Noiseau, Guillaume Jack Nicolas; Kovar, Desiderio; Becker, Michael FNanocrystalline films are promising in various fields such as microelectronics. Low temperature deposition techniques are desirable since they would enable the use of new substrates that are temperature sensitive, leading to a wide range of new applications. This thesis explores nanocrystalline silver film deposition by impacting nanoparticles (NP) onto a substrate, a technique that enables low process temperatures. This work aims at better understanding the physical parameters governing the sticking probability of NP upon impaction. To achieve this, various substrate materials have been used (metallic and non metallic) and the influence of the impacted substrate temperature has been studied, among other experiments. These parameters showed a significant influence on the collection efficiency of NPs. These experimental results are analyzed in light of published computer simulations studies predicting the behavior of impacting NP to deposit nanostructured films. Secondly, a study of the mechanical properties of the deposited films has been attempted. Compression tests have been carried out varying the applied load, loading time and process temperature. The produced films are nanocrystalline and porous (~70% relative density). Densification has been observed even at room temperature, and the goal of this study is to understand which mechanisms cause the densification to occur. The experimental densification data are compared with a model describing the densification of microparticles compacts by hot pressing that has been adapted to nanocrystalline silver, and the mechanisms leading to densification are discussed.Item Study of atomic-scale mechanisms for deposition of nanostructured films from nanoparticles(2015-12) Noiseau, Guillaume Jack Nicolas; Kovar, Desiderio; Becker, Michael F; Keto, John W; Bourell, David; Ferreira, PauloThe LAMA process (Laser Ablation of Microparticle Aerosols) is a manufacturing process for producing thin to thick films by supersonically impacting nanoparticles (NPs) onto a target substrate. The goal of this work is to study the mechanisms occurring at the atomic scale during LAMA within the impacting NPs and in the nearby substrate, and ultimately to use this knowledge to control the microstructure and properties of the resulting films. For example, dense, polycrystalline films or single-crystal (epitaxial) films would produce films with high conductivity and would make the LAMA process a good candidate for manufacturing films with properties that cannot be achieved at room temperatures by other film deposition techniques. Conversely, films with high porosity and surface area are desirable for catalysis and other applications. Thus, the ability to systematically tune the film microstructure through control of the process parameters would broaden the applicability of LAMA for film production. In this dissertation, the impaction of silver nanoparticles is studied in detail through a combination of experimental techniques. Scanning electron microscopy, transmission electron microscopy, and x-ray diffraction techniques are utilized to study the final microstructure of the films. The experimental results are compared with molecular dynamics (MD) simulations that allow both the evolution of the microstructure during impaction as well as the final microstructure after impaction to be studied. The influence of increasing the speed of impacting NPs on the morphology of Ag films is studied, and evidence is shown that film density can be increased using this route. Epitaxial deposition of NPs at a local level is observed using electron microscopy observations and the mechanisms for the occurrences of epitaxial deposition is presented. The challenges for obtaining fully epitaxial deposition of films are discussed.