Controlled Deposition of Nanostructured Hierarchical TiO2 Thin Films by Low Pressure Supersonic Plasma Jets.

Cecilia Piferi,Hector Eduardo Roman,Chiara Carra,Vittorio Morandi,Claudia Riccardi,Kateryna Bazaka,Igor Levchenko,Elisa Camilla Dell’Orto

doi:10.3390/nano12030533

Abstract

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.

Highlights

The demand for new materials with specific features at nano/micro-scales has been considerably increasing in recent times
In Plasma-assisted supersonic jet deposition (PA-SJD), clusters of molecules and nanoparticles are formed in inductively coupled plasma, transported in the expanding jet, and deposited on a substrate
We considered TiO2 nanoparticles as seeds of thin films, whose structure and morphology were analyzed and characterized

Summary

Introduction

The demand for new materials with specific features at nano/micro-scales has been considerably increasing in recent times. Nanoparticles (NPs) are often the building blocks of choice for the synthesis and assembly of advanced nanomaterials with high chemical reactivity and mechanical strength, as well as new optical and electrical properties This is because of their wide range of available chemistries, different shapes of varying sizes, large surface-to-bulk ratios, and quantum-confinement effects at small length scales. Light-sensitive diamond films have found applications in space technology [14], while other types of nanostructured aggregates are promising for the achievement of propulsion systems based on plasma technologies [15,16]. Both space applications are envisaged as critical for the advancement of affordable and miniaturized space assets [17]

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Results

Conclusion