Study and Characterization of Lanthanum Oxide Thin Films Grown by Pulsed Laser Deposition

The present work investigates the surface morphology, chemistry and the wettability properties of lanthanum oxide thin films grown using a physical vapor deposition technique, the pulsed laser deposition (PLD). A first set of sample was generated from a lanthanum target under reactive atmosphere, i.e. by introducing oxygen during the deposition. Another set of films was deposited using a lanthanum oxide target in non-reactive atmosphere. The film deposition was completed at the University of Illinois at Chicago (UIC). The influence of two parameters on the wettability properties of the grown surfaces was analyzed. A deposition parameter, the number of laser pulses, was increased from sample to sample to investigate the role played by the coating thickness on the physical, chemical and wetting characteristics of the thin films. The second parameter under analysis was the influence of the ultra violet light (UV) irradiation, an external stimulus, on the surface properties and wettability. The samples were irradiated under UV light for different time ranges and the exposed surfaces were then analyzed. The samples were characterized using optical microscopy, atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS) to analyze respectively the surface morphology, the surface roughness and chemistry of the films. Least but not last, the surface wettability properties were studied trough surface contact angle measurements completed using an optical tensiometer. All the analyses were completed in the laboratories of the Department of Applied Science and Technology, Politecnico of Turin and in the laboratories of surface characterization at the Politecnico of Turin, Alessandria.