Fundamental aspects of electrodeposition for the realization of plasmonic nanostructures

Electrodeposition is used for the preparation of nanoparticles and nanostructures that allow, in principle, surface plasmon excitation. The (photo)electrodeposition process of Rh and Au nanoparticles as well as of heterodimeric enzymes onto silicon surfaces is investigated and the resulting structures are discussed with regard to applications in photoelectroctalysis and biosensing. Electrodeposition of Rh onto H-terminated p-Si surfaces generates nanostructures of the metal nanoparticles with simultaneous oxidation of the substrate thus forming nano-dimensioned metal-oxide-semiconductor (MOS)-type contacts. The excess minority carrier harvesting in these nanoemitter structures, where semispherical space charge layers underneath the metal exist are discussed based on spectral sensitivity and capacitance measurements The deposition of Au nanoparticles by a combined chemical-electrochemical method on Si is presented as an example for sensing actuators where the resonance frequency is changed by adsorption. Similarly, site-selective deposition of the enzyme reverse transcriptase onto nanostructured (step-bunched) silicon serves as precursor experiment for biosensing in a Kretschmann-type ATR configuration. Future applications based on plasmonically active structures are outlined.