High-Speed, Low-Voltage, and Environmentally Stable Operation of Electrochemically Gated Zinc Oxide Nanowire Field-Effect Transistors

Authors

  • Babak Nasr,

    1. Institute for Nanotechnology, Karlsruhe Institute of Technology (KIT), D-76344 Eggenstein-Leopoldshafen, Germany
    2. KIT-TUD Joint Research Laboratory Nanomaterials, Technische Universität Darmstadt (TUD), Institute of Materials Science, Petersenstr. 32, D-64287 Darmstadt, Germany
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  • Di Wang,

    1. Institute for Nanotechnology, Karlsruhe Institute of Technology (KIT), D-76344 Eggenstein-Leopoldshafen, Germany
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  • Robert Kruk,

    1. Institute for Nanotechnology, Karlsruhe Institute of Technology (KIT), D-76344 Eggenstein-Leopoldshafen, Germany
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  • Harald Rösner,

    1. Institute for Materials Physics, University of Münster, Wilhelm-Klemm-Str. 10, D-48149 Münster, Germany
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  • Horst Hahn,

    1. Institute for Nanotechnology, Karlsruhe Institute of Technology (KIT), D-76344 Eggenstein-Leopoldshafen, Germany
    2. KIT-TUD Joint Research Laboratory Nanomaterials, Technische Universität Darmstadt (TUD), Institute of Materials Science, Petersenstr. 32, D-64287 Darmstadt, Germany
    3. Center for Functional Nanostructures, Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Str. 1, 76131 Karlsruhe, Germany
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  • Subho Dasgupta

    Corresponding author
    1. Institute for Nanotechnology, Karlsruhe Institute of Technology (KIT), D-76344 Eggenstein-Leopoldshafen, Germany
    • Institute for Nanotechnology, Karlsruhe Institute of Technology (KIT), D-76344 Eggenstein-Leopoldshafen, Germany.
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Abstract

Single-crystal, 1D nanostructures are well known for their high mobility electronic transport properties. Oxide-nanowire field-effect transistors (FETs) offer both high optical transparency and large mechanical conformability which are essential for flexible and transparent display applications. Whereas the “on-currents” achieved with nanowire channel transistors are already sufficient to drive active matrix organic light emitting diode (AMOLED) displays; it is shown here that incorporation of electrochemical-gating (EG) to nanowire electronics reduces the operation voltage to ≤2 V. This opens up new possibilities of realizing flexible, portable, transparent displays that are powered by thin film batteries. A composite solid polymer electrolyte (CSPE) is used to obtain all-solid-state FETs with outstanding performance; the field-effect mobility, on/off current ratio, transconductance, and subthreshold slope of a typical ZnO single-nanowire transistor are 62 cm2/Vs, 107, 155 μS/μm and 115 mV/dec, respectively. Practical use of such electrochemically-gated field-effect transistor (EG FET) devices is supported by their long-term stability in air. Moreover, due to the good conductivity (≈10−2 S/cm) of the CSPE, sufficiently high switching speed of such EG FETs is attainable; a cut-off frequency in excess of 100 kHz is measured for in-plane FETs with large gate-channel distance of >10 μm. Consequently, operation speeds above MHz can be envisaged for top-gate transistor geometries with insulator thicknesses of a few hundreds of nanometers. The solid polymer electrolyte developed in this study has great potential in future device fabrication using all-solution processed and high throughput techniques.

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