Self-assembled monolayers as capping agents and as a tunable resist for site-selective electrodeposition of patterned structures.

摘要

Several challenges need to be overcome in order to implement nanotechnology into existing devices or to fabricate novel devices. This thesis provides mechanistic details to understand some of the challenges and also provides new potential techniques to overcome certain issues.; To exploit the size dependent properties of nanoparticles, it is essential to control the particle size. It is shown that injection of octanethiol into suspensions of ZnO particles can be used to quench particle growth. X-ray photoelectron spectroscopy studies of the adsorption of octanethiol on ZnO single crystals indicate relatively weak adsorption of thiolate and sulfonate species dependent on the crystal orientation. These results suggest that adsorption of thiolate and sulfonate groups on ZnO particles in suspension prevent dissolution of the solid phase. Furthermore, the octanethiol is adsorbed sufficiently strongly to quench growth but can be easily removed for subsequent surface functionalization.; The shape of the absorbance edge for a suspension of semiconductor quantum particles is influenced both by the electronic transition and the distribution of band gaps in the system. Using a suitable model to relate the absorption energy to the particle radius, we demonstrate this relationship by inferring the particle size distribution from the absorbance spectrum of a suspension of ZnO quantum particles, and comparing it to the distribution obtained from transmission electron microscope images. This analysis is broadly applicable to quantum particle suspensions of many of the II--VI or III--V compound semiconductors.; A patterned self-assembled monolayer of octadecanethiol (ODT) on a gold or silver substrate is used as a tunable resist for the patterned electrodeposition of different metals on an electrode. Firstly, the electrodeposited metallic features have lateral dimensions that are dictated by the SAM with aspect ratios that are determined by charge conservation. Secondly, it is demonstrated that a patterned SAM of alkanethiol on Ag or Au surfaces can act as either a positive or negative resist by tuning the overpotential. A phase diagram showing the different regimes for silver deposition as a function of the surfactant chainlength and deposition potential is provided. Finally, the ability of creating Ag features by electroless deposition of silver using the surfactant as a catalyst is demonstrated. The ability to make micro- and nano-meter, complex, multicomponent features by electrodeposition and electroless deposition is shown with potential application in the fabrication of interconnects, GMRs and MTJs. (Abstract shortened by UMI.)