Dresden 2011 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 25: Transport
HL 25.5: Talk
Monday, March 14, 2011, 16:45–17:00, POT 151
Giant negative photoresistance of ZnO single crystals — •Jose Barzola-Quiquia1, Pablo Esquinazi1, Silvia Heluani2, Manuel Villafuerte3, and Andreas Pöppl4 — 1Division of Superconductivity and Magnetism, University of Leipzig, D-04103 Leipzig, Germany — 2Laboratorio de Física del Sólido, Dpto. de Física, FCEyT, Universidad Nacional de Tucumán, 4000 S. M. de Tucumán, Argentina — 3Dpto. de Física, Laboratorio de Física del Sólido, FCEyT, Universidad Nacional de Tucumán, Argentina and CONICET, 4000 S. M. de Tucumán, Argentina — 4Division of Magnetic Resonance of Complex Quantum Solids, University of Leipzig, D-04103 Leipzig, Germany
ZnO is a wide band gap semiconductor exhibiting the largest charge-carrier mobility among oxides. ZnO is a material with potential applications for short-wavelength optoelectronic devices, as a blue light emitting diodes and in spintronics. In this contribution we have measured the temperature dependence (30 K < T < 300 K) of the electrical resistance of ZnO single crystals prepared by hydrothermal method in darkness and under the influence of light in the ultraviolet range. The resistance decreases several orders of magnitude at temperatures T < 200 K after illumination. Electron paramagnetic resonance studies under illumination reveal that the excitation of Li acceptor impurities is the origin for the giant negative photoresistance effect. Permanent photoresistance effect is also observed, which remains many hours after leaving the crystal in darkness.