Download files
Abstract
This thesis introduces a unique strategy that allows micrometer sized redox events at any location of the electrode by addressing light with a single ohmic connection. The primary aim was the preparation of the well-passivated monolayer on the surface and chemical functionalization which is suitable for aqueous environment.
In this study, covalent immobilization of well-defined acetylene-terminated organic monolayers were prepared on hydrogen terminated n-type Si from single step hydrosilylation procedure from 1,8-nonadiyne, then azidomethylferrocene was clicked on the distal end of alkyne by click reaction. It is found that photo-oxidation, contra-thermodynamic redox reaction of ferrocene/ferricenium at the surface indicative of the anodic process occurs via a flux of valence-band holes.
The spatial resolution of the micrometer sized redox-events was mapped in surface generation- tip collection (SG/TC) by scanning electrochemical microscopy (SECM). It is also observed that the spatial resolution is inversely correlated with the thickness of Si. Furthermore, electron hopping between ferrocene has an effect on the spatial resolution of the redox process.
Having shown that light can switch on micro-meter sized electrochemistry, the spatial resolution information was used for read-outs of the feature on Si in 2D with the single connection. This includes decorating the Si surface with covalently bonded ferrocene lines of known widths ranging from 300 to 15 um by micro-fabrication technique. The measured catalytic current across the ferrocene modified region gives indication about the feature size.
Furthermore, light-driven process at a non-structured depleted semiconductor was used to locally (2D) grow soft conductive polymer features on non-conductive Si. The oxidation of a solution monomer by the minority carriers of Si is shown to be a viable approach for mask-free 2D writing of conductive features on surfaces.
Finally, the light driven electrochemistry technique was used to detect or enhance differences between different target DNA analytes.