07-05-2014
Será proferida pelo Professor Doutor Thomas Lippert (Department of Chemistry and Applied Biosciences, Laboratory of Inorganic Chemistry, ETH Zurich / Member of the PSI Research Committee / Editor of Applied Surface Science / Editorial Board of Materials), com o titulo "Thin Film Deposition by Pulsed Laser Deposition (PLD) and Laser-induced Forward Transfer (LIFT)", pelas 13H30 no anfiteatro Leopoldo Guimarães - CENIMAT.
Este seminário será proferido à porta aberta para quem estiver interessado em assistir.
Resumo:
Thin films of organic, polymeric, biological, and inorganic thin films are utilized in many applications, e.g. catalysis, microelectronics, sensors, food industry, tools, optics, decorative coatings, etc.. The preparation of these thin films can be achieved with a variety of tools, ranging from chemical to physical methods.
We focus on the application of lasers for the deposition of thin (oxide) films using pulsed laser deposition (PLD) and laser-induced forward transfer (LIFT) for thin films of a variety of materials with well defined dimensions. These films can either be applied as model systems e.g. for energy applications, or can be utilized in microdevices. The deposition of an ion conductor, i.e. yttria-stabilized zirconia, will be shown as an example for the application of PLD, while the deposition of materials to obtain SnO2 (and/or PLED materials) will be shown for LIFT. One of the key developments of the LIFT process has been the application of laser light absorbing layers between the substrate and the layer to be transferred which protect the transfer layer from the laser and allows therefore the transfer at lower laser fluences and also of sensitive materials (including biomaterials). Other materials that may be briefly mentioned are oxynitrides (photocatalysts), platinum for PEMFC, and multiferroics REMnO3.
In addition to the deposition method it is important to understand and control the processes which finally yield films with certain properties and compositions, which must be determined quantitatively for the thin films (100 nm range). We study the processes involved in PLD and LIFT using mainly time resolved shadowgraphy, emission spectroscopy/imaging as well as plasma mass spectrometry. Results will be presented, showing the presence and importance of negative ions in the laser-induced plasma as well as reactions and scattering of plasma species within the plasma and the background gas, which can result in a very narrow process window for obtaining films with the desired composition. Additionally, in-situ measurements of strain and the importance of strain in thin films will be shown for selected materials, i.e. ion conductors and multiferroic materials, which have been deposited by PLD.
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