Regensburg 2013 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 97: ZnO
HL 97.10: Vortrag
Freitag, 15. März 2013, 12:00–12:15, H16
Iron-induced gap states in ZnO thin films — •Rainer Pickenhain1, Florian Schmidt1, Sebastian Geburt2, Carsten Ronning2, Holger von Wenckstern1, and Marius Grundmann1 — 1Universität Leipzig, Institut für Experimentelle Physik II, Abteilung Halbleiterphysik, Linnéstraße 5, 04103 Leipzig — 2Institute for Solid State Physics, University of Jena, Helmholtzweg 3, D-07743 Jena
States of the transition metal iron within the bandgap of ZnO are not satisfyingly understood yet. Experimental evidence concerning internal transitions at about 1.8 eV [1] and 0.4 eV [2], respectively, of iron in Fe3+ and Fe2+ configuration exist. A concise experimental determination of the energetic position of these states within the bandgap was, however, not accomplished. In this study we present results on a ZnO thin film that was iron-implanted with a total fluence of 2 × 1011 ions/cm2. Due to the implantation/annealing process the net doping density decreased from 8×1016 cm−3 to 1× 1016 cm−3. By employing low-rate optical deep level transient spectroscopy (LR-ODLTS) we were able to detect two formerly not discovered states in the ZnO bandgap which we attribute to the incorporation of iron on zinc lattice site. These states lie at room temperature about 150 meV over the ZnO valenceband and 2200 meV below the ZnO conduction band minimum. Temperature-dependent measurements reveal that transition energies of these states increase similar to the ZnO bandgap down to 4 K.
[1] R. Heitz et al., Phys. Rev. B, 45, 8977 (1992).
[2] E. Malguth et al., Phys. Stat. Sol. (b) 245, 455 (2008).