Berlin 2008 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 50: ZnO: Tansport

HL 50.6: Vortrag

Donnerstag, 28. Februar 2008, 15:15–15:30, ER 164

Magnetoresistance in n-type conducting Co-doped ZnO — •Qingyu Xu¹, Lars Hartmann¹, Heidemarie Schmidt¹, Holger Hochmuth², Michael Lorenz², Daniel Spemann², and Marius Grundmann² — ¹Forschungszentrum Dresden-Rossendorf, Institut für Ionenstrahlphysik und Materialforschung, Bautzner Landstraße 128, 01328 Dresden, Germany — ²Universität Leipzig, Fakultät für Physik und Geowissenschaften, Institut für Experimentelle Physik II, Linnéstrasse 5, D-04103 Leipzig, Germany

Series of Co-doped Al-codoped ZnO films with electron concentration at 5 K ranging from 8.3×10¹⁷ cm⁻³ to 9.9×10¹⁹ cm⁻³ were prepared by pulsed laser deposition under different O₂ pressure and substrate temperature. The magnetoresistance (MR) effect was studied between 5 K and 290 K with fields up to 6 T, showing large electron concentration and temperature dependence. A large positive MR of 124 % has been observed in the film with the lowest electron concentration , while only negative MR of -1.9 % was observed in the film with highest electron concentration at 5 K. The positive MR is attributed to the quantum correction on the conductivity due to the s-d exchange interaction induced spin-splitting of the conduction band [1]. The negative MR is attributed to the magnetic field suppressed weak localization [1]. The modelled superimposed positive and negative MR agrees well with the experimentally observed MR and hints towards the physical origin of MR in Co-doped ZnO [2]. [1] P. A. Lee et al. Rev. Mod. Phys. 57, 287 (1985) [2] Q. Xu et al. Phys. Rev. B 76, 134417 (2007)