• Hofer, Ferdinand
• Fisslthaler, Evelin
• Oberaigner, Michael
• Haberfehlner, Georg
• Kothleitner, Gerald
• Lammer, Judith
• Radlinger, Thomas
• Grogger, Werner
• Albu, Mihaela
• Knez, Daniel

Abstract

Atomic-resolution imaging with a spherical aberration-corrected scanning transmission electron microscope (STEM) is now widely used for the study of interesting, complex material systems. This is owed both to the flexibility in detecting the electrons scattered off from matter, but also to the improved efficiency in collecting spectroscopic signals. Different variants of bright and dark-field imaging techniques provide unprecedented structural insights and electron energy-loss (EELS) or X-ray (EDXS) spectroscopy, have enabled elemental-specific imaging at that scale, while allowing for supplementary electronic and chemical information. The simultaneous collection of all these signals (“multi-modal STEM”) at various observation angles even, defining the technique of STEM-EELS/EDXS tomography, has given unprecedented insight into the 2D and 3D structural and physico-chemical material make-up.<br/>Fundamental research in physics, chemistry and materials science is currently strongly empowered by electron microscopy - to name a few topics: Understanding transport properties (such as charge localization, band versus ballistic transport or the interplay between lattice strain, band structure and charge transport…). Fundamental aspects of spintronics (such as the interplay of structure, chemistry and defects and their role in complex oxides, doped semiconductor materials and other nanostructures,…). Understanding the physics fundamentals of photonic materials (such as excitonic or polaronic coupling, photonic density of states 3D reconstructions, …). In materials science: Improving and understanding defect-engineering (such as the role of dislocations, and remedies to improve mobilities in electro-active materials ,…) or the understanding of phase formations and transitions (like precipitation formation in metals and alloys, role of coatings and additives of precursor powders used in 3D printed materials…).<br/>Overall, the STEM represents a quantitative instrument, which is capable of providing numerical data on some key properties of matter. The talk aims to give an overview to spectroscopic imaging in 2D and 3D, by showcasing some highly topical research questions on selected material systems.

Topics

• density
• impedance spectroscopy
• phase
• tomography
• semiconductor
• dislocation
• precipitation
• electron microscopy
• Energy-dispersive X-ray spectroscopy
• band structure
• electron energy loss spectroscopy