Wüest M. 51 Wykes M. 82 Yamaguchi M. 17 Ybarra G. 129 Yubero F ...
Wüest M. 51 Wykes M. 82 Yamaguchi M. 17 Ybarra G. 129 Yubero F ...
Wüest M. 51 Wykes M. 82 Yamaguchi M. 17 Ybarra G. 129 Yubero F ...
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JUNE 26 MONDAY MORNING<br />
RIVA-TF-MoM-OR.4 Ta 2 O 5 THIN FILMS PREPARED BY EVAPORATION AND<br />
IBAD METHODS: CHARACTERIZATION AND WETTING BEHAVIOUR UNDER UV<br />
IRRADIATION. V. Rico, J.P. Espinós, F. <strong>Yubero</strong>, F. Frutos*, A.R. González-Elipe. Instituto de<br />
Ciencia de Materiales de Sevilla (CSIC-Univ. Sevilla). Avda. Américo Vespucio s/n. 41092 Sevilla<br />
(Spain). *Dpto. Física Aplicada I, ETS Ingeniería Informática. Avda. Reina Mercedes s/n. 41012<br />
Sevilla (Spain)<br />
Ta 2 O 5 thin films have been prepared by evaporation from a tantalum oxide precursor and by assisting<br />
the growth of the films by oxygen and nitrogen ion bombardment (IBAD). The obtained thin films<br />
depict different microstructures and optical and dielectric properties. In general, the films prepared<br />
by evaporation have lower refraction indices that those prepared by IBAD. In this case a clear correlation<br />
exists between the ion current and energy and the properties of the films. The trend of dielectric<br />
properties of these thin films agrees with that defined by their optical properties. They also agree<br />
with the microstructrue of the films as determined by SEM. A particular type of films was found<br />
when prepared by evaporation under grazing conditions. These films depict a columnar microstructure<br />
with oblique columns and an extremely high porosity. Refraction indices ranging from 1.7 to 1.2<br />
have been obtained for these thin films.<br />
Another interesting property of these thin films refers to its wetting behaviour under UV light. In literature<br />
there are many papers dealing with the conversion of the TiO 2 surface from partially hydrophobic<br />
into fully hydrophilic by UV irradiation. In this work we also show that Ta 2 O 5 thin films present<br />
a similar behaviour changing from hydrophobic into hydrophilic by illumination. A careful<br />
study of this type of transformation is being carried out as a function of the microstructural and structural<br />
properties of the films. Doping of Ta 2 O 5 thin films with foreign cations and with nitrogen has<br />
revealed to be an effective way to induce a partial change in wetting angle by using visible light for<br />
the illumination.<br />
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