Surface Characterization of Materials at Ambient Conditions by Scanning Tunneling Microscopy (STM) and Atomic Force Microscopy (AFM)

Abstract

Abstract The creation of a new family of scanning probe techniques is one of the most exciting events in surface analysis in the last decade. The unique results have been achieved with the main representatives of these techniques—scanning tunneling microscopy (STM) and atomic force microscopy (AFM)-in the visualization of topographic and electronic features in the atomic scale. These new methods attracted many research teams. In a relatively short time, surfaces of different materials (metals, semiconductors, inorganic layered compounds, organic layers, single crystals, polymers, and biological objects) were examined by these techniques. This review is based on ambient conditions STM and AFM experiments conducted at the Materials Research Center of Freiburg University. Two main aspects of the results of imaging transition metal chalcogenides and halides, conductive organic salts, and polymers are emphasized. One is related to interpretation of the images, with the separation of the contributions of the electronic and topographic surface features being the main goal. The realization of this aim, which demands the development of theoretical approaches and comparative analysis with the participation of other surface techniques, will contribute strongly to our understanding of the surface properties of materials. The other aspect concerns the accumulation of knowledge about new methods because many important questions of STM and AFM are still open. The backgrounds of STM and AFM are discussed before the experimental results are presented.