Bulk and surface sensitive energy-filtered photoemission microscopy using synchrotron radiation for the study of resistive switching memories

In this thesis the applicability of energy-ltered photoemission microscopy for the analysis of future electronic devices for the information technology is studied. The long-term perspective is the analysis of the switching-dynamics in oxide-based nonvolatile resistive memories. These are regarded as promising new components in the development of more powerful processing units or storage devices, since the improvements of the classical silicon or magnetism- based technologies are approaching their physical limits. Nevertheless, the eciency and functionality of suitable material systems strongly depend on the quality and properties of their surfaces and interfaces. The energy-ltered photoemission microscopy provides a spatially resolved chemical study of these systems, especially in combination with high brilliance synchrotron light sources. The high photon intensities are needed, if characteristic core levels of a specimen should be analyzed with a high spatial and energy resolution. Studies of metal-insulator-metal structures based on the valence change eect in strontium titanate, which is a model system for resistive switching devices, showed that the spatial resolution needs to be in the 100 nm regime and the energy-resolution in the 100 meV regime to resolve the relevant changes in a switching cycle. Therefore, a big focus of this thesis lies on the determination of the relevant experimental parameters which are needed to fulll these requirements. Another challenging task is to study the functional layer of such a device through a capping electrode. Hard X-ray synchrotron radiation allows the use of high kinetic energy photoelectrons with an up to ten times lager information depth. In this thesis it is shown for the rst time, which spatial resolution can be achieved when detecting chemically dierent regions through cover layer thicknesses of up to 15 nm. Microscope-relevant topics like transmission and aberration eects are discussed with respect to the use of high kinetic electrons and illustrated by calculations