Characterization of surface defects produced with focused ion beams and exploration of applications for controlled growth of nanostructures

Abstract

In this work we combine two structuring methods for the production of nanostructures. For this purpose a new collaboration was launched between the TU Dortmund and the company Raith GmbH, supplier of nanofabrication tools. The first method is the fabrication of nanometer sized pits on graphite which was performed in our group before. These pits were used to produce metal clusters with a narrow size distribution. The second method is the fabrication of predefined structures with a beam of focused gallium ions. With this almost any pattern can be structured on any sample. The tool used here for this purpose is a new development of Raith (Raith ‘ionLiNE’). Within this thesis the applicability of this method was tested and new applications were found. The fabrication of nanostructures with feature sizes smaller than 50 nm is presented. These nano-structures were then used for the controlled growth of metal clusters, e.g. a pattern of single lead clusters with 100 nm pitch. New and special properties of the metal clusters (silver and lead) were observed. Another topic in this work is the structuring of graphite layers, called graphene. In the last years the interest in this material arose particularly because of its special electronic properties. It will be shown that we are able to produce corresponding structures with our method. The structures are mainly investigated with a low temperature ultra high vacuum scanning tunneling microscope (STM). The experiments are combined with Monte Carlo simulations for a better understanding of the results.