WETTABILITY OF OXIDE THIN FILMS PREPARED BY PULSED LASER DEPOSITION : NEW INSIGHTS.

Abstract

The objective of the thesis is to investigate the wettability of good quality oxide thin films prepared by pulsed laser deposition (PLD). Thin films of oxides of rare earth elements were made on YSZ substrates and the water contact angle (WCA) for the films was measured after environmental stabilization for about 6 weeks. Most of the films had WCA slightly below the hydrophobic mark (90?) and a few were found to be hydrophobic. Temporal measurements of WCA was done on epitaxial single crystal oxide films to investigate the role of environmental stabilization on wettability of the oxide film surfaces. It was found that all the oxide films in the study are intrinsically hydrophilic with a very low WCA in the range 10-20? when measured fresh from PLD vacuum chamber. XPS measurements suggest that the films on exposure to atmosphere get hydrated and surface adsorbs hydrocarbons (mostly alkanes) which causes the WCA to increase with time.