Tailoring molecule nanostructures on insulating surfaces investigated by non-contact atomic force microscopy

Self-assembled molecular structures were investigated on insulating substrate surfaces using non-contact atomic force microscopy. Both, substrate preparation and molecule deposition, took place under ultra-high vacuum conditions. First, C60 molecules were investigated on the TiO2 (110) surface. This surface exhibits parallel running troughs at the nanometer scale, which strongly steer the assembly of the molecules. This is in contrast to the second investigated surface. The CaF2 (111) surface is atomically flat and the molecular assemblyrnwas observed to be far less affected by the surface. Basically different island structures were observed to what is typically know. Based on extensive experimental studies and theoretical considerations, a comprehensive picture of the processes responsible for the island formation of C60 molecules on this insulating surfaces was developed. The key process for the emergence of the observed novel island structures was made out to be the dewetting of molecules from the substrate. This new knowledge allows to further understand andrnexploit self-assembly techniques in structure fabrication on insulating substrate surfaces. To alter island formation and island structure, C60 molecules were codeposited with second molecule species (PTCDI and SubPc) on the CaF2 (111) surface. Depending on the order of deposition, quiet different structures were observed to arise. Thus, these are the first steps towards more complex functional arrangements consisting of two molecule species on insulating surfaces.