tesi R. Miscioscia.pdf - EleA@UniSA

116 Exceptions in morphology-mobility relationship
necessary to modulate the channel current[21]. As we can state by
observing table 4, film roughness increases of few Angstroms when
film is deposited on the glass substrate. For the sake of our
investigation similar values of mean roughness have been obtained,
therefore a comparison can be considered consistent from this point of
view.
3.2.3 Sol-gel PFTEOS:TEOS processing
When PFTEOS and TEOS are put in solution, the silicic
derivatives hydrolyze giving Si-OH groups which are able to undergo
to condensation. Such condensation process happens when the
material is in its thin-film phase (after spin-coating) by means of
thermal curing at 150°C. During this process the material forms
networks of chemical bindings between functionalized Si-O-Si and
perfluoroalkyl groups which tend to migrate to the film surface giving
rise to enhanced hydrophobic interface properties[22] (see figure 2).
figure 2: schematization of perfluoroalkyl groups localization on PFTEOS:TEOS film surface
The described sol-gel process is summarized in figure 3