University of Twente Student Theses


Ellipsometric study on gaseous layers at the solid/water interface

Atesci, Hüseyin (2013) Ellipsometric study on gaseous layers at the solid/water interface.

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Abstract:In this thesis, ellipsometry was used to investigate whether gas-enrichment occurs at the solid/water interface, and whether there is a difference in enrichment between hydrophilic and hydrophobic samples. The samples used were silicon with 277 nm thermal oxide on top (hydrophilic) and an additional silicone oil coating (hydrophobic). The samples were held in a liquid cell which could be filled with degassed, He-saturated, and N2-saturated water. The SiO2 thickness was taken as the fit parameter. Long (>300 minutes) dynamic scans were made on hydrophobic and hydrophilic samples in different water ambients. It was found that it is likely that gas-enrichment occurs at the solid/water interface due to the qualitative difference observed in the fitted SiO2 thickness over time between degassed and He-saturated water ambients. This change was noticeable in the first 150 minutes of measurement and was observed for both hydrophilic and hydrophobic samples. In the long term, the fitted SiO2 always increased, which is unlikely to be caused by gas-adsorption through diffusion, but likely to be caused by contaminants. The hydrophilic samples generally showed a larger change in the fitted SiO2 thickness than the hydrophobic samples. The exact reason why this happens is unclear, although it could be attributed to the tendency of hydrophilic silicon oxide to be easily contaminated.
Item Type:Essay (Master)
Faculty:TNW: Science and Technology
Subject:33 physics
Programme:Nanotechnology MSc (60028)
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