Zinc Oxide nanostructured thin films were grown by a novel plasma assisted vapour deposition method, which aims to combine the versatility of deposition processes that are mediated by plasma with the capability to control particles diffusion and nucleation. For this purpose, the proposed approach spatially separates into two different vacuum chambers the creation of zinc oxide from a metalorganic precursor from the actual film growth, thanks to the extraction of a supersonic jet of plasma seeded by the precursor fragments. The characterization of the reactor in different plasma conditions has been carried out by means of optical emission spectroscopy (OES). ZnO films with different degrees of purity, thickness uniformity, as well as different morphologies can be obtained varying the deposition parameters. The samples profiles have been collected in order to evaluate deposition rates and films uniformity. The as-prepared as well as annealed thin films were characterized by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) to evaluate their chemical composition and purity. According to Raman analyses, the annealed samples are high-purity wurtzite-type crystalline zinc oxide films. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) confirm a surface morphology characterized by columnar structures.

Plasma-assisted supersonic jet deposition (PA-SJD) is a precise technique for the fabrication of thin films with a desired nanostructured morphology. In this work, we used quadrupole mass spectrometry of the neutral species in the jet and the extensive characterization of TiO₂ films to improve our understanding of the relationship between jet chemistry and film properties. To do this, an organo–metallic precursor (titanium tetra–isopropoxide or TTIP) was first dissociated using a reactive argon–oxygen plasma in a vacuum chamber and then delivered into a second, lower pressure chamber through a nozzle. The pressure difference between the two chambers generated a supersonic jet carrying nanoparticles of TiO₂ in the second chamber, and these were deposited onto the surface of a substrate located few centimeters away from the nozzle. The nucleation/aggregation of the jet nanoparticles could be accurately tuned by a suitable choice of control parameters in order to produce the required structures. We demonstrate that high-quality films of up to several µm in thickness and covering a surface area of few cm² can be effectively produced using this PA-SJD technique.