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Berlin 2008 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 50: ZnO: Tansport

HL 50.2: Talk

Thursday, February 28, 2008, 14:15–14:30, ER 164

Magnetotransport and Transport Properties of Compacted ZnO Nanoparticles — •Sonja Hartner1,2, Moazzam Ali3, Hartmut Wiggers2, Axel Lorke1, and Markus Winterer31Experimental Physics and CeNIDE, Universität of Duisburg-Essen, Duisburg, Germany — 2Institute for Combustion and Gas Dynamics, Universität of Duisburg-Essen, Duisburg, Germany — 3Nanoparticle Process Technology, Universität of Duisburg-Essen, Duisburg, Germany

The present study investigates the magnetotransport properties of compacted pellets of nanosized ZnO powders using Hall measurements and impedance spectroscopy (IS). Measurements performed at room temperature show a clear Hall voltage and an ohmic transport behavior. The doped ZnO particles exhibit n-type semiconducting behavior. A charge carrier concentration which is far below the value of bulk material and a mobility of 5 cm2/Vs, which is half of the value for bulk material are determined. The compacted ZnO nanoparticles show a decreasing mobility with increasing carrier concentration. The IS was performed in air and in hydrogen atmosphere at temperatures ranging from 323K to 673K. By doping the ZnO with 7% aluminum, the conductivity increases by two orders of magnitude in comparison to undoped ZnO. At 523K in hydrogen atmosphere, the conductivity is up to seven orders of magnitude higher than for room temperature and exhibits a positive temperature coefficient as it is known from metallic conductors. The differing properties are attributed to a change in the oxygen vacancy concentration of the sample material.

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