Dr hab. Gerhard Brauer, Forschungszentrum, Dresden

Positron annihilation spectroscopy - application to ZnO single crystals

(W sali Rzewuskiego) Positron Annihilation Spectroscopy (PAS) is now a well-established tool for the study of electronic and defect properties of bulk solids, whereas mono-energetic positron beams are needed to investigate thin films and surfaces. As an introduction, the application and basic physics behind PAS methods will be explained briefly. Zinc oxide (ZnO) is a potential semiconductor suitable for fabrication of visible and UV light emitters and detectors as well as high-temperature electronics. However, to achieve this goal, a full understanding of the role of lattice defects is needed as they largely control the optical and electrical properties. Here, a summary of our recent research results to identify lattice defects in ZnO single crystals will be presented which includes the application of radioactive positron sources, a mono-energetic positron beam, and also theoretical calculations. Finally, an outlook about future work will be given. This includes the construction of an accelerator-based and pulsed intense positron beam, and the study of ZnO nanorods.