Regensburg 2019 – wissenschaftliches Programm

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 13: Microscopy, Tomography and Spectroscopy with X-ray Photons, Electrons, Ions and Positrons (joint session KFM/HL)

KFM 13.3: Vortrag

Mittwoch, 3. April 2019, 10:10–10:30, H47

Atomic Resolution Differential Phase Contrast STEM investigations of electric fields in ZnO nanostructures — •Julius Bürger, Julia Weiß, Dennis Meinderink, Katja Engelkemeier, Wolfgang Bremser, Guido Grundmeier, Mirko Schaper, and Jörg K. N. Lindner — Paderborn University, Paderborn, Germany

Differential phase contrast (DPC) is one of the most promising techniques for future research with scanning transmission electron microscopy (STEM) giving rise to a new range of measurable material properties. By detecting phase gradients, i.e. by quantifying the electron beam deflection on a specimen site with a segmented detector, electric and magnetic field components can be detected. With an installed C_s-corrector the projected charge carrier distribution and electric fields can be estimated with a resolution much smaller than typical atomic distances. Zinc oxide (ZnO) is a piezoelectric material with excellent optical and semiconductor properties. Hence ZnO is promising for green energy harvesting converting mechanical stress into electric energy. For optimization of ZnO-based piezoelectric devices the operating principles and charge carrier displacements resulting from mechanical stress have to be understood down to the sub-nanoscale. In this presentation, the electric fields and charge carrier distributions of bent ZnO nanobelts, ZnO nanorods, nanowall network hollow body microspheres and ZnO-functionalized carbon fibers are revealed for the first time by DPC-STEM both at a macroscopic scale and with atomic resolution.