Dresden 2017 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 64: Poster: Photovoltaics and Optics
HL 64.11: Poster
Mittwoch, 22. März 2017, 15:00–19:00, P1C
Is the oxygen vacancy in ZnO connected to the E3 deep level defect? — •R. Pickenhain1, M. Schmidt2, H. von Wenckstern1, A. Pöppl1, G. Benndorf1, and M. Grundmann1 — 1Universität Leipzig, Fakultät für Physikund Geowissenschaften, Inst. für Exp Physik II,Linnéstr. 5, 04103, Leipzig, Germany — 2Helmholtz-Centre for Environmental Research, Permoserstr. 15, 04318 Leipzig, Germany
The E3 defect is typically incorporated in bulk crystals and thin films of ZnO. We examined this defect in ZnO single crystals with deep level transient spectroscopy (DLTS), optical DLTS (ODLTS), electron paramagnetic resonance (EPR) and photoluminescence(PL). With DLTS- and ODLTS we demonstrate experimentally that the E3 level in ZnO can bind two electrons and exhibits negative U-property. The thermal activation energy of the defect is about 280 meV and corresponds to the emission of two electrons into the conduction band. The effective correlation energy of the negative U-defect was determined from the measured photo cross section σo(hν) to be Ucor∼ −1 eV. Temperature dependent EPR experiments suggest that the oxygen vacancy VO is the microscopic origin of the E3 defect. Further we find with temperature dependent PL that the E3 defect has a radiative recombination for the transition VO0 ⇒ VO+ with a peak maximum energy of 2.09 eV. The comparatively low experimental value of 280 meV of the thermally activated VO0 ⇒ VO2+ transition should re-stimulate discussions on the contribution of the oxygen vacancy to the free electron density and on its role in the difficulty to obtain p-type ZnO.