PIUMA is an innovative plasma source employed to deposit nanostructured thin films by Plasma Assisted Supersonic Jet Deposition. This deposition process takes place in two different vacuum chambers (a reaction chamber and a deposition chamber) and it’s based on a 2 step process: first of all, an argon and oxygen plasma is created in the reaction chamber at low pressure (around 0.1 mbar), then a precursor is vaporized and injected into the chamber. Here the reactive plasma dissociates the precursor (titanium based precursors such as TTIP or TEOT have been used to deposit TiO2). This kind of process provides an excellent control on the stoichiometry and the chemical composition of the deposit. The deposition chamber, connected with the reaction through a nozzle, is maintained at a lower pressure (around 0.001 and 0.01 mbar) and, when the pressure difference is high enough, a supersonic jet expansion of the plasma allows the nucleation and aggregation of molecular clusters which are thus deposited on a substrate at an appropriate position. The reaction and deposition processes are separated and this allows a high control of the film growth and of its morphology by varying the parameters that characterize the supersonic expansion (as the pressure in the two chambers or the temperature) or the deposition process (such as the distance of the substrate from the nozzle or its roughness).

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