Majority-carrier mobilities in undoped and n -type doped ZnO epitaxial layers

Authors

  • T. Makino,

    Corresponding author
    1. Department of Material Science, University of Hyogo, Kohto, Kamogoori-cho 678-1297, Japan
    2. Photodynamics Research Center, Institute of Physical and Chemical Research (RIKEN), Sendai 980-0845, Japan
    • Phone: +81 791 58 0372, Fax: +81 791 58 0137
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  • Y. Segawa,

    1. Photodynamics Research Center, Institute of Physical and Chemical Research (RIKEN), Sendai 980-0845, Japan
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  • A. Tsukazaki,

    1. Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba, Sendai, 980-8577, Japan
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  • A. Ohtomo,

    1. Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba, Sendai, 980-8577, Japan
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  • M. Kawasaki

    1. Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba, Sendai, 980-8577, Japan
    2. Also at: Combinatorial Exploration Material Science and Technology, National Institute for Materials Science, Tsukuba, Japan
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Abstract

Transparent and conductive ZnO:Ga thin films are prepared by laser molecular-beam epitaxy. Their electron properties were investigated by the temperature-dependent Hall-effect technique. The 300-K carrier concentration and mobility were about ns ∼ 1016 cm–3 and 440 cm2/V s, respectively. In the experimental ‘mobility vs concentration’ curve, unusual phenomenon was observed, i.e., mobilities at ns ∼ 5 × 1018 cm–3 are significantly smaller than those at higher densities above ∼1020 cm–3. Several types of scattering centers including ionized donors and oxygen traps are considered to account for the observed dependence of the Hall mobility on carrier concentration. The scattering mechanism is explained in terms of inter-grain potential barriers and charged impurities. A comparison between theoretical results and experimental data is made. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

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