Formation and optical characterisation of colloidal gold monolayers

We study the deposition of charge-stabilised gold nanocolloids on silicon substrates, which have been derivatised with (aminopropyl)triethoxysilane. Atomic force microscopy (AFM) and spectroscopic ellipsometry are employed to investigate the nanocrystal monolayers ex situ. Analysis of AFM images provides evidence that the formation of colloidal monolayers is governed by random sequential adsorption. The results indicate that the ionic strength of the suspension influences the spatial distribution of the colloids. In situ reflectometry also shows the effect of the (tunable) electrostatic interactions between the gold particles on the deposition kinetics. Especially in the saturation regime these interactions dominate the self-assembly.