Silicon is an attractive semiconductor material for wide-ranging applications, especially when taking advantage of the larger surface area of silicon micro and nanowires. Surface functionalization with self-assembled monolayers of (in)organic molecules can be employed to tune the functionality of a substrate towards a desired application. Specifically, solar-to-fuel and sensing devices highly benefit from the use of oxide-free monolayers, since any silicon oxide layer functions as an insulating layer and retards electrical contact with the substrate. For this purpose, hydrosilylation can be used to couple terminal unsaturated carbon-carbon bonds, i.e., 1-alkenes or 1-alkynes, onto H-terminated Si which leads to direct Si-C bond formation. The research described in this thesis aims at the formation of molecular monolayers on H-terminated silicon micro and nanowires for solar-to-fuel and sensing devices. In summary, the results described in this thesis demonstrate the versatility of molecular monolayers on H-terminated silicon structures. When applying a monolayer by hydrosilylation, the absence of an insulating oxide layer allows electrical contact between the functionalized headgroup of the monolayer and the substrate. This enables the fabrication of solar-to-fuel devices, in which molecular monolayers ensure electrical passivation of the surface, a controllable doping concentration, covalent or noncovalent immobilization of catalysts, and spatioselective functionalization to couple different catalysts onto the same device. For sensing devices, oxide-free monolayers establish a higher stability of the sensor owing to the direct Si-C bonds, a higher sensitivity due to the selective functionalization of the sensing area only, and a higher specificity when using supramolecular chemistry to make an analyte-specific sensor. These findings offer new perspectives for the development of stabilized silicon micro/nanosystems with engineered functionalities.
|Award date||12 May 2017|
|Place of Publication||Enschede|
|Publication status||Published - 12 May 2017|