Untersuchungen der Defektzentren in neuartigen Zinkoxid-Nano-Partikeln mit in situ-Elektron-Spin-Resonanz (ESR) und Optischer Spektroskopie
Zusammenfassung der Projektergebnisse
In this project, by the aid of spectroscopic tools such as impedance, Raman, photoluminescence (PL) and electron paramagnetic resonance (EPR) spectroscopy, various types of ZnO nanostructures has been investigated. It is well known that ZnO is highly defective wide band gap semiconductor material and its point defect structure is still in debate. By this project we have synthesized ZnO by various novel chemical techniques and have controlled the crystalline size. Combination of EPR and PL spectroscopic methods revealed for all types of ZnO nanostructures which are synthesized differently, a common defect structure. And from this results we have modeled a global ZnO defect model namely core-shell model. According to this global defect structure model: ZnO defects which are consist of localized electrons are located in the core of ZnO which gives similar as the bulk properties having g ~1.96 and the electrons which are delocalized are placed at the surface of the ZnO which are act as shallow donors or free electrons giving g ~2.0 value. In this project electrical resistivity, metal ion doping, light and atmospheric interaction of defect centers has been also intensively investigated and the results were published in high-rank journals and presented in international conferences.
Projektbezogene Publikationen (Auswahl)
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EPR and photoluminescence spectroscopy studies on the defect structure of ZnO nanocrystals, Phys. Rev. B 86 (2012) 114113
Kaftelen, Hülya; Ocakoglu, Kasim; Thomann, Ralf; Tu, Suyan; Weber, Stefan & Erdem, Emre
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Investigation of Intrinsic Defects in Core-Shell Structured ZnO Nanocrystals, J. Appl. Phys. 111 (2012) 113712
Parashar, S. K. S.; Murty, B. S.; Repp, S.; Weber, S. & Erdem, E.
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Electron paramagnetic resonance (EPR) study of ZnO varistor material, J. Phys. Condens. Matter 26 (2014) 115801
Baraki, Raschid; Zierep, Paul; Erdem, Emre; Weber, Stefan & Granzow, Torsten
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Local coordination of Fe3+ in ZnO nanoparticles: Multi-frequency EPR and Newman superposition model analysis, J. Phys. Condens. Matter 26 (2014) 155803
Açıkgöz, Muhammed; Drahus, Michael D; Ozarowski, Andrew; van Tol, Johan; Weber, Stefan & Erdem, Emre
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Microwave power, temperature, atmospheric and light dependence of intrinsic defects in ZnO nanoparticles: A study of electron paramagnetic resonance (EPR) spectroscopy, J. Alloys and Compounds 605 (2014) 34-44
Erdem, Emre
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Effects of MnO doping on the electronic properties of Zinc Oxide: 406 GHz EPR spectroscopy and Newman superposition model analysis, J. Appl. Phys. 118 (2015) 175705
Yüksel Price, Berat; Hardal, Gökhan; Açıkgöz, Muhammed; Repp, Sergej & Erdem, Emre
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Charge transfer and surface defect healing within ZnO nanoparticle decorated graphene hybrid materials, Nanoscale 8 (2016) 9682-9687
Pham, Chuyen V.; Repp, Sergej; Thomann, Ralf; Krueger, Michael; Weber, Stefan & Erdem, Emre
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Competing effects between intrinsic and extrinsic defects of pure and Mn-doped ZnO nanocrystals, J. Nanoparticle Research 18 (2016) 109
Ruf, Thomas; Repp, Sergej; Urban, Joanna; Thomann, Ralf & Erdem, Emre
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Controlling the exciton energy of Zinc Oxide (ZnO) quantum dots by changing the confinement conditions, Spectrochim. Acta A 152 (2016) 637-644
Repp, Sergej & Erdem, Emre
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Defect evolution of non-stoichiometric ZnO quantum dots, J. Phys. Chem. C 120 (2016) 25124-25130
Repp, Sergej; Weber, Stefan & Erdem, Emre
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Hydrothermal synthesis and defect structures in ZnO nanopowder. RSC Advances 6 (2016) 39511-39521
S. Yildirimcan, K. Ocakoglu, S. Erat, F. M. Emen, S. Repp, E. Erdem
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Defect induced p-type conductivity in ZnO at high temperature: EPR spectroscopy, Nanoscale 9 (2017) 10983-10986
Erdem, Emre
