Quantitative surface analysis at atomic resolution, atom-probe field ion microscopy

Abstract

There are at least three different aspects of a high resolution microscopy of the surface, namely the atomic imaging aspect, the chemical analysis aspect, and the energy spectroscopy aspect. The atom-probe field ion microscopy (FIM) is a combination of a field ion microscope and a single ion detection sensitivity time-of-flight spectrometer. With the field ion microscope, the atomic structure of the surface and the bulk of a solid, and the behavior of single atoms and small atomic clusters on the surface can be investigated. In chemical analysis, surface layers and interface layers of a solid can be analyzed atom by atom and atomic layer by atomic layer. Thus compositional variations in surface and impurity segregations, in grain boundary segregations, in precipitations, in oxidation and corrosion, and in compound layer formation etc., can be studied quantitatively with subnanometer spatial resolution. In energy spectroscopy, the binding energy of surface atoms from well defined adsorption sites, the formation of cluster ions in pulsed-laser stimulated field desorption, resonance tunneling phenomena, and the orientation and isotope effects in field dissociation of compound ions by atomic tunneling etc., can be studied with a mass and energy resolution of one to two parts in 100,000. Some of our recent studies in these areas are briefly described.